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Position of the American Dietetic Association and

American Society for Nutrition: Obesity, Reproduction,

and Pregnancy Outcomes

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BSTRACTiven the detrimental influence ofaternal overweight and obesity on

eproductive and pregnancy out-omes for the mother and child, it ishe position of the American Dieteticssociation and the American Society

or Nutrition that all overweight andbese women of reproductive agehould receive counseling on the rolesf diet and physical activity in repro-uctive health prior to pregnancy,uring pregnancy, and in the inter-onceptional period, in order to ame-iorate these adverse outcomes. Theffect of maternal nutritional statusrior to pregnancy on reproductionnd pregnancy outcomes is of greatublic health importance. Obesity inhe United States and worldwide hasrown to epidemic proportions, withn estimated 33% of US women clas-ified as obese. This position paperas two objectives: (a) to help nutri-ion professionals become aware ofhe risks and possible complicationsf overweight and obesity for fertil-ty, the course of pregnancy, birthutcomes, and short- and long-termaternal and child health out-

omes; and (b) related to the com-itment to research by the Americanietetic Association and the Ameri-

an Society for Nutrition, to identifyhe gaps in research to improve ournowledge of the risks and complica-ions associated with being overweightnd obese before and during preg-ancy. Only with an increased knowl-dge of these risks and complicationsan health care professionals developffective strategies that can be imple-ented before and during pregnancy

0002-8223/09/10905-0018$36.00/0

sdoi: 10.1016/j.jada.2009.03.020

18 Journal of the AMERICAN DIETETIC ASSOCIATIO

s well as during the interconceptionaleriod to ameliorate adverse outcomes.Am Diet Assoc. 2009;109:918-927.

OSITION STATEMENTiven the detrimental influence of ma-

ernal overweight and obesity on repro-uctive and pregnancy outcomes for theother and child, it is the position of

he American Dietetic Association andhe American Society for Nutrition thatll overweight and obese women of re-roductive age should receive counsel-ng prior to pregnancy, during preg-ancy, and in the interconceptionaleriod on the roles of diet and physicalctivity in reproductive health, in or-er to ameliorate these adverse out-omes.

besity in pregnancy carries withit not just increased risks for thepregnant woman during gesta-

ion, but also risks for the futureealth of the child, or, in public healtherms, the health of the next genera-ion. The long-term goal of healthare professionals must be to reducehe proportion of women who arebese during the reproductive periodnd increase public awareness abouthe importance of a healthful lifestylehealthful diet, moderate to vigorousevels of physical activity, and emo-ional well-being) before and duringregnancy. In accordance with a re-ent recommendation by the Ameri-an College of Obstetrics and Gyne-ology (ACOG) (1), the Americanietetic Association (ADA) and themerican Society for Nutrition rec-mmend that preconceptional and in-erconceptional counseling about pos-ible complications associated withbesity and how to prevent thoseroblems be available to all women ofeproductive age.Members of ADA work in various

ettings that provide care to women of B

N © 2009

eproductive age. Thus, the first ob-ective of this position paper is foregistered dietitians; dietetic techni-ians, registered; and other healthare professionals to become aware ofhe risks and possible complicationsf overweight and/or obesity for fertil-ty, the course of pregnancy, birthutcomes, and short- and long-termaternal and child health outcomes.he second objective, related to theommitment to research by the ADAnd the American Society for Nutri-ion, is to identify the research gapshat need to be filled to improve ournderstanding of the risks and com-lications associated with being over-eight or obese before and duringregnancy. Only with an increasednderstanding of these risks andomplications can health care profes-ionals develop effective strategieshat can be implemented prior to anduring pregnancy, as well as duringhe interconceptional period, to ame-iorate adverse outcomes.

ONTEXT FOR THIS POSITIONTATEMENThe effect of maternal nutritional sta-us prior to pregnancy on reproduc-ion and pregnancy outcomes is ofreat public health importance andas been extensively studied overime. A woman’s prepregnancy wei-ht has been used as a marker ofutritional status. Being underwei-ht, defined as a body mass indexBMI; calculated as weight kg/m2)ess than 18.5, may reflect chronic nu-ritional deficiency, whereas a highMI (�25) reflects an imbalance be-

ween energy intake and expenditure,nd thus varying degrees of adiposity.he National Institutes of Health andhe International Obesity Task Forceave defined overweight (or preobese)s a BMI of 25 to 29.9, and obese as a

MI of 30 or more (2). In most clinical

by the American Dietetic Association

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ettings and epidemiological studies,MI is used to estimate adiposity be-

ause of its strong correlation with fatass as measured by hydrodensitom-

try and dual-energy x-ray absorpti-metry. It has limitations, however,n that it does not account for differ-nces that may exist in fat mass byex, age, and race/ethnicity (3).Obesity in the United States andorldwide has grown to epidemic pro-ortions. The latest data from the Na-ional Health and Nutrition Exami-ation Survey (1999-2004) indicatehat among nonpregnant women age0 to 39 years, approximately 25%re overweight and 28% are obese, ofhom 6% are considered extremelybese (BMI �40) (4). Among adoles-ent girls, 12 to 19 years old, approx-mately 30% are at or above the 85thercentile of BMI—for-age and 16.4%re considered obese (4). On average,besity among women of all ageseems to have peaked at 33%, with noppreciable increase between 1999-000 and 2003-2004 (4). Overweightnd obesity are associated with manyomorbidities that affect a woman’sealth, including reduced fertility (5).In any given year, approximately 4illion women in the United States

ecome pregnant. Among women whoecome pregnant, the shift towardigher prepregnancy weight in recentears is evident (6). Obesity duringregnancy has been associated withestational diabetes, gestational hy-ertension, pre-eclampsia, birth de-ects, Cesarean delivery, fetal macro-omia, perinatal deaths, postpartumnemia, and childhood obesity (7,8).ot only are more women beginningregnancy with high BMIs, but morere also gaining in excess of the 1990nstitute of Medicine (IOM) recom-endations for gestational weight

ain (8,9).* This excessive weightain compounds the pregnancy com-lications mentioned previously. It

s particularly problematic for over-eight and obese women for whom

he optimal range of weight gain is

*The 1990 Institute of Medicineeport uses the following body massndex cut points to define weight sta-us groups which are different fromhe National Heart, Lung, and Bloodnstitute; �19.8 underweight, �19.8o 26 normal weight, �26 to 29 over-

seight, and �29 obese.

ncertain because there were limitedata in 1990 when the guidelinesere created and, as such, the recom-ended range of weight gain (15 to 25

b for overweight and at least 15 lb forbese) is exceeded by most overweightnd obese women. It is also uncertainf overweight and obese adolescentshould gain in the upper range of theecommendation (10). Furthermore,verweight and obese women areore likely to maintain excess weight

fter delivery (8). In affluent countries,any women retain some weight with

ach successive pregnancy, gainingore weight than their nonpregnant

ounterparts (8). Those who gain moreeight during pregnancy are more

ikely to retain more weight and con-inue on a higher weight trajectoryhroughout their lifetime comparedith women who gain less weight (8).eight gain during pregnancy has

lso been shown to have implicationsor the child’s future risk of beingverweight (8).

HE EFFECT OF OVERWEIGHT ANDBESITY ON FERTILITY AND CONCEPTIONbesity is a state of excess adipose

issue, which is critical in controllinghe regulation of sex hormone avail-bility due to its ability to store lipidteroids such as androgens. Estrogenroduction and the concentration ofex hormone-binding globulin in thelood are correlated with variouseasures of body fat. There also

eems to be a strong association be-ween obesity and insulin resistance,hich is thought to reduce fertil-

ty (5).Body weight and composition are

elieved to play an important role inubertal maturation, with leptin alsoeing important in this biological pro-ess (11). Excessive weight gain atounger ages is associated with ear-ier menarche (12,13) and both highbsolute weight and change in weightre associated with menstrual prob-ems. Obesity in adolescence andoung adulthood, as opposed to dur-ng infancy, is more strongly associ-ted with amenorrhea, oligomenor-hea, and long menstrual cycles14,15).

There is some evidence of increasedime to conception for obese compa-ed with normal-weight women (16,7), particularly among women who

moke cigarettes (18). Obesity is also G

May 2009 ● Journa

strong risk factor for polycysticvarian syndrome, which results inenstrual irregularities and chronic

novulation. The central distributionf fat, as measured by waist-to-hipatio, is also related to reproductiveunctioning, with higher rates of in-ertility associated with higher waist-o-hip ratios (19,20).

It is estimated that 25% of ovula-ory infertility in the United Statesay be attributable to overweight

nd obesity among women of repro-uctive age (16). The adverse effect ofbesity on conception is manifestedven among women who seek assistedeproductive technology, with obeseomen manifesting lower implanta-

ion and pregnancy rates, as wells higher miscarriage rates and in-reased pregnancy complications (14).

HE EFFECT OF OVERWEIGHT ANDBESITY ON PREGNANCY OUTCOMESaternal Complications during Pregnancyuring pregnancy, numerous meta-olic adjustments occur to increasehe availability of energy, nutrients,nd oxygen to the developing fetus. Inonobese women, these metabolicdjustments pose no increased riskor complications. However, in obeseomen, who already have aberra-

ions in glucose and lipid metabolism,he further adjustments induced byormonal changes in pregnancy cre-te a metabolic milieu that enhan-es the risk for metabolic disorders,uch as gestational diabetes mellitusGDM) and pre-eclampsia. The greaterhe degree of maternal obesity, theigher the risk of developing theseetabolic disorders (21). For exam-

le, the risk of GDM is increased two-old in overweight compared withormal-weight women, and it is in-reased eightfold in the severelybese (BMI�40) (22). Pre-eclampsias approximately twice as prevalentn overweight women (BMI 25 to 30)nd approximately three times asigh in obese women (BMI �30)

21,23). Pre-eclampsia is more com-on in obese women with GDM than

n women without GDM. The coexist-nce of these two metabolic disordersuggests a similarity in the underly-ng biological mechanisms. Tight glu-ose control in women with GDMeems to reduce the risk for pre-clampsia (23). Surveys show that

DM tends to occur more frequently

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n Asian, Hispanic, and Native Amer-can women than in African-Ameri-an and white women (24-26).

Because maternal obesity is a riskactor for GDM, obese women aresually screened for glucose intoler-nce early in prenatal care. Initially,50-g oral glucose challenge (ie, the

lucose challenge test) is given andlasma glucose values are measuredhour later. If the values exceed a

utoff, usually between 130 and 140g/dL (7.2 and 7.8 mmol/L), an oral

lucose tolerance test is done. A diag-osis of GDM is made if two or morelasma glucose values exceed estab-ished cutoffs (27). If one postloadlasma glucose level exceeds thetandard, glucose tolerance may beonsidered to be impaired, but usuallyo counseling or treatment is given. Ev-dence is accumulating, however, thatne abnormal glucose value is associ-ted with complications similar tohose seen with GDM (28).

Normally, the insulin sensitivity oferipheral tissue decreases approxi-ately 50% to 60% in late pregnancy

n lean women; the decrease is greatern obese women (23). Thus, hyperin-ulinemia is common in all pregnantomen, with higher levels seen inverweight and obese women. If pan-reatic insulin secretion is adequate,omen will remain glucose tolerant

hroughout gestation and GDM doesot develop. It is thought that thehift toward reduced insulin sensitiv-ty (or increased insulin resistance)uring late pregnancy occurs to limitaternal glucose utilization and con-

erve it for diffusion across the pla-enta to the fetus. Maternal hyper-nsulinemia also enhances the ratef maternal adipocyte fat oxidation,hich releases more fatty acids

nto circulation for use as a fuelource by the mother (29). The freeatty acids are converted to trigly-erides in the liver and returned toirculation as very-low-density li-oproteins, resulting in high very-ow-density lipoprotein concentra-ions in late pregnancy (30). Thisyslipidemia usually disappears afterelivery.It is not unusual for a mild inflam-atory state to occur in obese preg-ant women with glucose intolerance31) because proinflammatory cyto-ines (ie, interleukin-6 and tumor ne-rosis factor-�) are produced by the

lacenta as well as adipose tissue o

20 May 2009 Volume 109 Number 5

32). Research suggests that theseroinflammatory cytokines may con-ribute to the decrease in insulin sen-itivity seen in obese women withDM (31).The risk of GDM in obese womenay be reduced by increasing non–

nsulin-mediated glucose use by pe-ipheral tissues, primarily skeletaluscle (23) by increasing physical ac-

ivity. An increased use of large skel-tal muscles during physical activityay be beneficial. Also, a high-fiber

nd high—complex carbohydrate dietr a low—glycemic index diet may re-uce the insulin need after a meal,nd theoretically decrease beta cellailure, but efficacy data are limited.

Gestational hypertension and pre-clampsia are also more common inverweight and obese pregnant wo-en. Gestational hypertension, de-

ned as a systolic blood pressure of ateast 140 mm Hg or a diastolic bloodressure of at least 90 mm Hg, affectspproximately 6% to 17% of nullipa-ous women and 2% to 4% of multip-rous women (33). Approximately0% of women with gestational hy-ertension diagnosed before 30eeks’ gestation develop pre-eclamp-

ia, a syndrome involving gestationalypertension plus proteinuria (34).he cause of pre-eclampsia is un-nown, but it is currently thought toe related to an inadequate placentallood supply, possibly due to mater-al hypertension, which causes pla-ental oxidative stress and the re-ease into maternal circulation oflacental factors that trigger an

nflammatory response. Because sub-linical inflammation is more com-on in obese individuals, obeseomen may enter pregnancy withre-existing inflammation that en-ances their risk for pre-eclampsia.

aternal Complications in the Peripartumeriodesarean deliveries and associatedorbidities are more common among

bese women. For example, in onearge multicenter trial of overweightnd obese women, the Cesarean de-ivery rate was 30% for nulliparousomen with a BMI less than 30, 34%

or those with a BMI of 30 to 34.9, and8% for women with a BMI of 35 to9.9 (35). The effect of weight lossetween two deliveries on the risk

f a subsequent Cesarean delivery t

as not been carefully assessed (23).fter Cesarean delivery, overweightr obese women have more postoper-tive complications, such as woundnfection/breakdown, excessive bloodoss, deep venous thrombophlebitis,nd postpartum endometritis than doormal-weight women. The length of

abor also is longer in overweight andbese women (36).Although high BMIs are generally

ssociated with higher hemoglobinevels during pregnancy, they are as-ociated with an increased risk ofostpartum anemia (37). It is thoughthat these inconsistent findings areue to the higher prevalence of post-artum hemorrhage and abdominaleliveries among obese women. Mac-osomia may also cause significantostpartum blood loss by causing per-neal rupture and hemorrhage andengthening the period of vaginal dis-harge of blood after delivery.

irth Outcomesnfants born to obese mothers have

higher prevalence of congenitalnomalies than do offspring of nor-al-weight women, suggesting thataternal adiposity alters develop-ent in the sensitive embryonic pe-

iod (30). In a study of 10,240 USomen enrolled in the National Birthefects Prevention Study, 1997-2002,

he odds ratio of structural birth de-ects ranged from 1.3 to 2.1 amongbese compared with nonobese moth-rs (7) Neural tube defects (NTDs) arepproximately twice as high amonghildren of obese women, with spinaifida being more common than anen-ephaly (7). Other birth defects morerequent in offspring of obese womennclude oral clefts, heart anomalies,ydrocephaly, and abdominal wallbnormalities. The underlying meta-olic basis for increased anomaliesn obese women is not known. It ishought that poor glycemic controlay play a role. Consuming a diet

igh in sucrose and other high-glyce-ic foods increased the risk of NTDs

y twofold in women among alleight groups, but the risk was four-

old among obese women (BMI �29)38). Although low folic acid statusas been associated with NTDs, theelationship between maternal obe-ity and NTDs persists after control-ing for self-reported folic acid in-

akes, suggesting that other factors

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uch as poor glycemic control contrib-te to congenital anomalies in obeseomen (30).Recently, maternal obesity has

merged as a risk factor for intrauter-ne fetal death and stillbirth (death ofetus before onset of labor) (13). In aanadian study of more than 84,000omen, a maternal pregravid bodyeight more than 68 kg increased the

isk of fetal death by 2.9-fold afterdjusting for age, diabetes, and hy-ertensive disorders (39). Also, a sys-ematic review of articles on riskactors for antepartum stillbirtheported a threefold increased risk fortillbirth among obese women afterdjusting for age, parity, maternal di-betes, and hypertension as well as aumber of social factors (40). It ishought that the relatively recent in-rease in antepartum stillbirth in de-eloped countries may be linked toaternal age or obesity because both

f those factors influence metabolicdjustments to pregnancy.The incidence of preterm birth

ends to decrease, rather than in-rease, with increasing pregravidMI once medical inductions are ac-

ounted for in the analysis (23). Anndependent effect of maternal obe-ity on preterm labor or prematureupture of membranes has not beendentified after controlling for under-ying medical or obstetric issues.ome have even suggested that ma-ernal obesity protects against spon-aneous preterm labor (41). The riskf having a small-for-gestational ageull-term baby (ie, newborn witheight �10th percentile for gesta-

ional age) tends to decrease with in-reasing maternal BMI, whereas theisk of having a large-for-gestationalge (LGA) baby (�90th percentileeight-for-gestational age) increasesy approximately 60% compared withormal-weight women (42) Althoughregestational diabetes has a greaterffect on the frequency of LGA thanaternal obesity does (42), more of

he LGA babies are born to obeseomen than women with diabetes be-

ause maternal obesity is more prev-lent than diabetes (43). Severalountries have reported an increasen mean birth weight over the pastecade and an increase in the propor-ion of large babies (44). One explana-ion for this increase could be the in-rease in maternal BMI over the

ame time period. No consistent effect c

f maternal BMI on infant birthength has been reported.

FFECTS OF MATERNAL OVERWEIGHT/BESITY ON SHORT- AND LONG-TERMHILD HEALTH STATUSsing a lifecourse approach, it haseen shown that maternal pregravideight has an early and persistentffect on childhood overweight statuss well as a dynamic effect on therocess of overweight development33,45). Most studies that have exam-ned maternal pregravid BMI andhildhood weight status have found aositive association with adjusteddds ratios ranging from two to four46-49).

There is some evidence of an asso-iation between maternal overwei-ht or obesity and decreased ratesf breastfeeding. Breastfeeding haseen well-demonstrated to haveany protective effects against child-

ood morbidities, including the devel-pment of obesity later in life (45,50-3). Specifically, a high BMI beforeonception has been shown to be in-ersely related to the successful initi-tion of breastfeeding, the duration ofactation, and the amount of milk pro-uced (54). This is especially problem-tic given the finding from the 1996ational Longitudinal Survey ofouth (47), which showed that chil-ren whose mothers were obese prioro pregnancy and who were neverreastfed had a six times greater riskf being overweight compared withhildren whose mothers were normaleight and who breastfed for at leastmonths. The mechanisms by which

verweight and obesity adversely af-ect lactation performance include

echanical difficulties associatedith latching on and proper position-

ng of the infant; the high Cesareanection rates among this subpopula-ion, which delays the onset of firstuckling; and a lower prolactin re-ponse to suckling at 48 hours andore after delivery, which may com-

romise milk production and, overime, lead to early cessation of lacta-ion (55).

There is some evidence linking ma-ernal overweight and obesity, inde-endent of GDM, to the developmentf the metabolic syndrome (obesity,ypertension, dyslipidemia, and glu-ose intolerance) in the offspring. In a

ohort of 84 children who were LGA i

May 2009 ● Journa

nd 95 who were appropriate-for-ges-ational age at birth, Boney and col-eagues (56) showed that the risk ofaving two or more components of theetabolic syndrome at age 11 was

.81 (95% confidence interval�1.03,

.19), if the mother was obese prior toregnancy.Overall, these findings on the effect

f maternal overweight and obesityn long-term child health status haverave implications for perpetuatinghe cycle of obesity and its correlatesn subsequent generations.

NTERVENTIONS TO REDUCEBESITY-RELATED PROBLEMS PRIORO AND DURING PREGNANCYeight loss seems to improve men-

trual functioning, ovulation, and in-ertility in obese women (5,17). Evenmong women with polycystic ovar-an syndrome, as little as a 5% reduc-ion in weight has been associatedith improved fertility (5). However,aintaining this weight loss can pose

roblems for women of childbearingge. Women who have reported re-trained eating, dieting, and or weightycling prior to pregnancy have beenhown to gain more weight duringregnancy than those who do not re-ort these behaviors (57).Among morbidly obese women,

ariatric surgery is becoming moreommon and its effect on reproductiveutcomes is emerging. After surgery,omen are instructed to consume,000 to 1,200 kcal/day and to take aaily multivitamin and some addi-ional form of a vitamin B-12 supple-ent. Those who are interested in be-

oming pregnant are told to wait untilheir weight loss stabilizes, after ap-roximately 12 to 18 months, and toeek care from an obstetrician spe-ializing in high-risk pregnancy. Caseeries studies report improved preg-ancy and fertility rates with weight

osses in the range of 10.6 to 44 kg58). Complications of bariatric sur-ery that are particularly worrisomeuring pregnancy include vomiting,alabsorption of several nutrients,

nd inadequate pregnancy weightain, which may have adverse effectsn the fetus. Two studies using lapa-oscopic adjustable gastric bandingound mean weight gains of approxi-ately 10 kg, mean birth weights of 3

o 3.5 kg, and prevalence of pregnancy-

nduced hypertension in the range of

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% to 10%, and prevalence of ges-ational diabetes from 6% to 16%59,60). In the one study that had aomparison group (59), women afterhe banding had lower gestationaleight gains, lower incidence of ges-

ational diabetes and hypertension,ut no difference in mean birtheight compared with a matched

bese cohort. In another study thatsed biliopancreatic diversion withuodenal switch, among 109 womenho became pregnant postopera-

ively, 90 reported weight gains of.1�5.9 kg, eight reported weight lossuring pregnancy, and 11 reported noeight gain (61). The study repor-

ed lower incidence of macrosomiaut higher small-for-gestational agehen comparing birth outcomes forll women before and after surgery.astly, one study used laparascopicoux-en-Y gastric bypass and exam-

ned birth outcomes of 21 women whoecame pregnant within 1 year of sur-ery compared with 13 women whoelayed pregnancy until after 1 year.hey found no differences in mode ofelivery, pregnancy complications, orirth weights; however, mean gesta-ional weight gain was significantlyower in the group that became preg-ant within 1 year (4 vs 34 lb) (62).learly, more studies are warranted

o determine if perinatal outcomesre affected among women who be-ome pregnant after using this ap-roach for long-term weight loss. Fur-hermore, long-range outcomes ofhese infants also warrant carefultudy.Other weight-loss practices foromen of reproductive age have been

overed in previous ADA positions—Weight Management” and “Nutritionnd Women’s Health” (63,64). TheCOG recommends that obese wo-en undertake a weight-loss pro-

ram before pregnancy (65). Thatould be ideal, but it is unlikely thatany women who have been over-eight or obese will reach normaleight prior to conception. Thus,

ome intervention during pregnancyerits consideration.The ACOG (1) recommends deter-ining pre- or early pregnancy BMI

t the first prenatal visit and thenecommending a pregnancy weightain within the IOM guidelines forach BMI category (9). There is somepidemiological evidence suggesting

hat women are more likely to gain g

22 May 2009 Volume 109 Number 5

ithin the IOM guidelines if theirealth care provider makes this rec-mmendation (66). Four groups havetudied behavioral interventions torevent excessive weight gain inregnancy (67-69). The studies wereot done exclusively in overweight orbese women. One of the four studies,community-based intervention (69),

ailed to find an effect of the interven-ion on gestational weight gain. Twof the three interventions were basedn the United States (67,70). In Polleynd colleagues’ study (67), normal-eight women in the interventionroup had lower percentages that ex-eed the IOM recommendation; how-ver, the intervention did not workor overweight/obese women. In thelson and colleagues study (70), a sig-ificant effect was seen only amonghe low-income women; adjusted oddsatio�0.41 (95% confidence inter-al�0.20, 0.81) for excessive gesta-ional weight gain associated with thentervention. The fourth study, donen Finland, found that women in-reased their intakes of fruit, vegeta-les, and high-fiber bread, but therevalence of excessive weight gainas not reduced (68). Clearly, moreork is warranted in this area.Only two groups have initiated in-

ervention programs to limit weightain, not just prevent excessive gain,n obese pregnant women (71,72). Ar-al and colleagues (71) studied a di-tary intervention, with or withoutxercise, to restrict weight gain inbese women with GDM. No controlroup was included in the study.eight gain averaged 0.3 kg/week

uring the last trimester in the dietroup and 0.1 kg/week in the dietith exercise group. The 1990 IOM

ecommended that overweight wo-en (BMI 26 to 29) should gain

pproximately 0.3 kg/week (9). Thus,he investigators achieved that goalith the diet intervention and re-uced the rate of gain further whenxercise was added. When the womenere divided into two groups—thoseho gained and those who lost weightr had no weight change—no differ-nces in the measured pregnancy andetal outcomes were observed. Claes-on and colleagues (72) initiated anntervention with weekly counselingnd aqua aerobic classes in 155 obeseomen (BMI �30) and 193 control

ubjects. The intervention women

ained less weight than the control a

ubjects during pregnancy (8.7 vs1.3 kg) and weighed less at the post-artum check-up. Birth weight didot differ between the two groups inhis small study. These two studiesuggest that intervention programsnitiated during pregnancy can con-rol weight gain in obese women, buturther studies are needed in largeramples of women, particularly tovaluate possible adverse outcomes.

nterventions to Prevent Metabolicisorders in Obese Womens mentioned earlier, obese womenave an increased risk for gestationaliabetes, gestational hypertension,nd pre-eclampsia. Interventions in-olving dietary components or nutri-nt supplements have been used torevent these disorders in pregnancy,lthough the studies have not beenone exclusively in obese women. Be-ause these problems are common inbese women, a brief review follows.The role of dietary carbohydrate in-

akes in reducing the risk of GDM orlucose intolerance has been inves-igated by several groups. In an ob-ervational study, Saldana andolleagues (73) found that higherarbohydrate intakes, presumablyrom refined carbohydrate sources,ncreased the risk of glucose intoler-nce in nondiabetic women. Interven-ion studies also show that reducingefined carbohydrates decreases glu-ose intolerance. Fraser and collea-ues (74) reported that postprandial in-ulin responses were attenuated inonobese pregnant women consum-

ng more than 50 g of fiber per day,ompared with control subjects’ con-umption of approximately 12 g of fi-er per day. The authors concludedhat the usual increase in plasmansulin levels after meals among preg-ant women in the Western hemi-phere are an unphysiological responseo dietary fiber depletion. In a smalltudy of 12 lean women, Clapp (75)ompared the effect on glycemic controlf either a low– or high–glycemic indexiet consumed from before conceptiono term. The amount of carbohydrateas similar in both groups, but at lateregnancy the glycemic response to aeal in the low-glycemic diet groupas similar to prepregnancy values,hereas it was nearly doubled in theigh-glycemic diet group. Bronstein

nd colleagues (76) compared the se-

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um glucose and insulin response toow- and high-glycemic test meals andound that the response of both wasower with low glycemic meals in bothean and obese women. Epidemiologicata from the Nurses’ Health Studylso showed that a low-glycemic, high–ereal fiber diet reduced the risk forDM by approximately one half (77).In addition to modifications in the

ype of carbohydrate, adjustments inhe type of fat may also reduce glu-ose intolerance and GDM. In a studyf 171 pregnant Chinese women, in-reased body weight, decreased poly-nsaturated fat intake, and a low ra-io of dietary polyunsaturated toaturated fat independently pre-icted glucose intolerance (78). Bond colleagues (79) also found thatlucose intolerance in pregnant womenithout conventional risk factors (eg,

amily history, age, and BMI) was in-reased with high intakes of saturatedat and reduced with high intakes ofolyunsaturated fat. Further studiesre needed in obese women, but theseata suggest that reducing the glyce-ic load and increasing cereal fiber

nd polyunsaturated fatty acid intakesay reduce GDM or glucose intoler-

nce during pregnancy.Nutritional interventions to reduce

he risk of gestational hypertensionr pre-eclampsia have primarily in-olved nutrient supplements. Severalalcium supplementation trials haveeen done, and the results were re-iewed in a recent meta-analysis (80).t was thought that supplemental cal-ium might prevent pre-eclampsia be-ause low levels of cellular calciumause vasoconstriction by stimulatingelease of either parathyroid hormoner renin. Data show that calciumupplementation is effective amongomen with low calcium intakes; cal-

ium reduced the risk of pre-eclamp-ia by approximately 50% withoutny adverse effects. No benefit haseen observed in women with ade-uate calcium intakes.Antioxidant supplementation has

lso been tested as a means to pre-ent pre-eclampsia. However, twoandomized controlled trials provid-ng 1,000 mg vitamin C and 400 IU ofitamin E from the first or second tri-esters to term were not beneficial

81,82). Initiating the interventionrior to conception or very early inregnancy when the placenta is de-

eloping may be necessary. n-3 fatty a

cids reduce blood pressure in non-regnant individuals, but attempts toeduce blood pressure with n-3 fattycid supplements in pregnancy haveielded contradictory results (83).alt restriction was recommended

or several years to prevent edemand/or pre-eclampsia, but a recent re-iew of its efficacy found no benefit84). Thus, except for the beneficialffects on the risk of pre-eclampsia, aseen with supplemental calcium inomen with low calcium intakes,one of the other nutritional inter-entions have proven to be efficacious.Because the marked increase in

ipid and lipoprotein components inate pregnancy may induce proathe-ogenic changes in the fetal aorta, theffect of a cholesterol-lowering diet onaternal, cord, and neonatal lipids

nd on pregnancy outcomes was stud-ed in a group of nonobese (meanMI�24) Norwegian women (85).he dietary intervention (which pro-oted consumption of fish, low-fateats and dairy products, whole

rains, and fruits and vegetablesrom mid-pregnancy to term), reduced

aternal total and low-density li-oprotein cholesterol levels but didot alter cord and neonatal levels.he marked reduction in the inci-ence of preterm deliveries in the in-ervention group suggests that fur-her studies of the role of diet onreterm deliveries are needed.Although the data are sparse, there

s some evidence that moderate phys-cal activity throughout gestation re-uces the risk of GDM and pre-clampsia by nearly one half (86).hysical activity activates the en-yme AMPK (adenosine monoph-sphate-activated protein kinase),hich increases glucose transport

nto muscle, enhances fat oxidation,nd reduces insulin resistance (87).lso, physical activity may reduce theisk of pre-eclampsia by reducing cir-ulating levels of inflammatory cyto-ines (88). Women who exercisedhroughout pregnancy (eg, perform-ng endurance exercises four or moreimes per week) gained significantlyess fat and had significantly lowerncreases in tumor necrosis factor-�nd leptin during gestation (89). Mod-rate, consistent physical activityay be an effective way to reduce

oth subclinical inflammation and in-ulin resistance, two features of met-

bolic disorders in obese pregnant h

May 2009 ● Journa

omen. Once again, no interventiontudies using physical activity to pre-ent metabolic disorders have beenone with obese pregnant women.

MPIRICAL RESEARCH NEEDED TO FILLAPSe identified the following research

aps that are critical to advancing ournderstanding of the influence of be-

ng overweight or obese on reproduc-ion and pregnancy outcomes. In-reased understanding would helpuide appropriate nutrition counsel-ng prior to and during pregnancy, asell as in the postpartum and inter-

onceptional periods.Mechanisms by which body weight

nfluences reproductive function anderformance are not well-understoodnd need further clarification. Mater-al subclinical inflammation and vas-ular dysfunction are associated withany of the complications occurring

uring pregnancy in overweight andbese women. In addition, the effectf maternal BMI status, insulin resis-ance, and inflammation on placentalunction and birth outcomes needso be examined in greater detail. Fi-ally, the roles of maternal diet andhysical activity before and duringestation on these metabolic disor-ers need further elucidation beforetandards of clinical and dietary carean be established.The Dietary Reference Intakes for

otal energy indicate that for aealthful birth outcome, pregnantomen should, on average, consumen extra 340 kcal/day in the secondrimester and 452 kcal/day in thehird trimester (90). Whether this en-rgy prescription is suitable for over-eight and obese women is unknown.esearch is needed in this area toupport dietary recommendationshat result in appropriate weight gainor overweight and obese pregnantomen. There also seems to be a lack

f research related to how informa-ion is given to pregnant women re-arding diet and maternal weightain in various systems of healthare, whether they follow it, and howhis information influences their be-avior.Limited evidence suggests that the

omposition and pattern of gesta-ional weight gain is altered by a highrepregnancy BMI; only one study

as shown that obese women tend

l of the AMERICAN DIETETIC ASSOCIATION 923

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o gain less fat during the secondrimester than do normal-weightomen (8). Compared with under-eight and normal-weight women, inbese women, the relationship be-ween maternal weight gain andirth weight is attenuated (8). Thisuggests that the maternal metabolicdjustments required to support fetalrowth are less dependent on gesta-ional weight gain in obese womenhan in nonobese women. More re-earch is needed on the relationship ofhe amount, composition, and patternf weight gain for overweight, obese,nd severely obese women to maternalnd child health outcomes in the shortnd long term. Those data are neededo revise the IOM gestational weight-ain recommendations for pregnantomen and to suggest an upper limit

or obese women; in the 1990 report,bese women were advised only to gaint least 6 kg (15 lb) (9).The relationship between maternal

besity and decreased breastfeedingeeds further elucidation. Given therotective effect of breastfeeding onbesity development in the child andother, we need to know why obeseomen are less likely to breastfeed

uccessfully in order to develop suc-essful intervention strategies.

It is unknown whether a high ma-ernal prepregnancy BMI contributeso an intrauterine developmental pro-ramming process that increases theisk of childhood overweight and long-erm disease, or whether the obeseg-nic environment of the home andamily is the primary determinant ofhildhood obesity and subsequent dis-ase. It is also uncertain if infantsorn to obese women are actually fat-er or if the higher birth weight isecause of greater lean body mass.e need better epidemiological stud-

es that can tease out these effects.A more systematic approach and

onger-term follow-up studies areeeded of women who become preg-ant after bariatric surgery to evalu-te the effects of surgery on perinatalnd long-term child health outcomes.More intervention studies are

eeded to determine if GDM, pre-clampsia, and pregnancy-inducedypertension can be prevented with

nterventions related to diet and/orhysical activity during pregnancy,nd if there is a critical time whenhese interventions should be imple-

ented. This will help in establishing w

24 May 2009 Volume 109 Number 5

he importance of preconceptional vsrenatal counseling for behaviorshat can ameliorate these conditions.

OLES AND RESPONSIBILITIES OF FOODND NUTRITION PROFESSIONALSORKING WITH OVERWEIGHT/OBESEOMEN PRIOR TO AND DURING

REGNANCY AND IN POSTPARTUM ANDNTERCONCEPTIONAL PERIODSs experts in food and nutrition

hroughout the lifespan, registered di-titians and other food and nutritionrofessionals are in a unique positiono provide counseling to overweightnd obese women to ameliorate the ad-erse effect of a high prepregnancyeight on reproductive, pregnancy,nd long-term maternal and childealth outcomes. We acknowledge thatcomprehensive guide for evidence-

ased counseling of obese women needso written. Based on the present knowl-dge it is important to provide counsel-ng to obese women during the precon-eptional, prenatal, postpartum, andnterconceptional periods regardinghe following topic areas:

During the preconceptional pe-riod, overweight and obese womenshould receive counseling on strate-gies to obtain and remain at a health-ful weight according to guidance pro-vided in the ADA position “Nutritionand Women’s Health” (64). This in-cludes information about successfulweight-loss practices, healthful eat-ing both in the types of food andquantities, folic acid supplement use,as well as information about beingphysically active. In addition, theyshould be counseled about potentialpregnancy and fetal complications ifthey are to become pregnant. Docu-menting a measured weight andheight in their medical records wouldalso be beneficial for later use relatedto the gestational weight-gain goals.During pregnancy all overweightand obese women should be in-formed about current IOM gesta-tional weight gain target goals†, beadvised to not lose weight duringpregnancy, and counseled abouteating healthful foods during preg-nancy as described in the ADA po-

†At the time of this report the re-ised Institute of Medicine guidelines

ere not published.

sition “Nutrition and Lifestylefor a Healthy Pregnancy Out-come” (91) and in MyPyramid forPregnancy (www.mypyramid.gov/mypyramidmoms) (92). They shouldbe encouraged to be physically ac-tive and be made aware of theACOG guidelines for exercisingduring pregnancy (www.acog.org/publications/patient_education/bp045.cfm) (93). Per the ACOGCommittee Opinion report (1), foodand nutrition professionals shouldencourage and support the screen-ing of obese women for gestationaldiabetes upon presentation at thefirst clinic visit and repeated screen-ing later in pregnancy if resultsare initially negative. Early in preg-nancy, overweight and obese womenshould be encouraged to breastfeedand be made aware of the benefits forboth her and her child’s health.During postpartum and inter-conceptional periods, specialemphasis should be placed on thesupport of breastfeeding initiationand duration. Frequent early con-tact after hospital discharge wouldbe advantageous for this purpose.During lactation, the overweightand obese woman should be coun-seled on a healthful diet that is nu-trient-dense and also advised to notincrease energy intake to compen-sate for milk production becausethat will help minimize postpar-tum weight retention (94). At the6-week postpartum visit, womenshould be encouraged to consider aweight-loss program that includes aphysical activity component (95)and be screened for postpartum de-pression and type 2 diabetes if ges-tational diabetes was confirmedduring the pregnancy (1). They mayneed encouragement in taking timeout for themselves to relieve thestress of motherhood, and guidance onthe developmentally appropriate intro-duction of solid foods for the infant.These guidelines should address fivekey areas:Œ developmental signs of when a

baby is ready for solids;Πwhat foods are appropriate to

feed and why;Πdeveloping healthful eating hab-

its to last a lifetime;Πfood safety concerns specific to in-

fants; and

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Œ developing a child’s motor skillsand physical activity patterns (96).

Other visits during the postpartumnd interconceptional period woulde advantageous because this wouldllow monitoring and supportingeight-loss practices and encourag-

ng adherence to the 2005 Dietaryuidelines for Americans (97).

e thank the reviewers for theirany constructive comments and

uggestions. The reviewers were notsked to endorse this position or theupporting paper.

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0. Institute of Medicine. Dietary Reference In-takes for Energy, Carbohydrate, Fiber, Fat,Fatty Acids, Cholesterol, Protein, and AminoAcids. Part I. Washington, DC: The NationalAcademies Press; 2002.

1. American Dietetic Association. Position of theAmerican Dietetic Association: Nutrition andlifestyle for a healthy pregnancy outcome.J Am Diet Assoc. 2008;108:553-561.

2. MyPyramid for Pregnancy. MyPyramidWeb site. http://www.mypyramid.gov/mypyramidmoms. Accessed June 3, 2008.

3. American College of Obstetricians and Gy-necologists. Women’s Health: Exercise andFitness. American College of Obstetriciansand Gynecologists Web site. http://www.acog.org/publications/patient_education/bp045.cfm. Accessed June 3, 2008.

4. Institute of Medicine. Nutrition During Lac-tation. Washington, DC: The National Acad-emies Press; 1991.

5. Lovelady CA, Garner KE, Moreno KL, WilliamsJP. The effect of weight loss in overweight, lac-tating women on the growth of their infants.N Engl J Med. 2000;342:449-453.

6. Butte N, Cobb K, Dwyer J, Graney L, HeirdWC, Rickard KA. Start Healthy StayHealthy: Feeding Guidelines: Starting Sol-ids Foods. American Dietetic AssociationWeb site. http://www.eatright.org/ada/files/infant_book.pdf. Published 2005. AccessedFebruary 4, 2009.

7. US Department of Health Human Services,US Department of Agriculture. DietaryGuidelines for Americans, 2005. Health.govWeb site. http://www.health.gov/Dietary

Guidelines/dga2005/document/default.htm.Published 2005. Accessed February 4, 2009.

The last review of the research literature for finalizing this position paper was completed in the spring of 2008.ADA position adopted by the House of Delegates Leadership Team on October 23, 2008. This position is in effect untilDecember 31, 2012. ADA authorizes republication of the position, in its entirety, provided full and proper credit isgiven. Readers may copy and distribute this paper, providing such distribution is not used to indicate an endorse-ment of product or service. Commercial distribution is not permitted without the permission of ADA. Requests to useportions of the position must be directed to ADA headquarters at 800/877-1600, ext. 4835, or ppapers@eatright.org.

Authors: American Dietetic Association: Anna Maria Siega-Riz, PhD, RD (The University of North CarolinaGillings School of Global Public Health, Chapel Hill, NC); American Society of Nutrition: Janet C. King, PhD(Children’s Hospital Oakland Research Institute, Oakland, CA).

Reviewers: American Dietetic Association: Jeanne Blankenship, MS, RD (University of California Davis MedicalCenter, Davis); Sharon Denny, MS, RD (ADA Knowledge Center, Chicago, IL); Mary H. Hager, PhD, RD, FADA(ADA Government Relations, Washington, DC); Donna B. Johnson, PhD, RD (University of Washington, Seattle);Debra A. Krummel, PhD, RD (University of Cincinnati, Cincinnati, OH); Cheryl Lovelady, PhD, RD, LDN (Univer-sity of North Carolina, Greensboro); Esther Myers, PhD, RD, FADA (ADA Scientific Affairs, Chicago, IL); WeightManagement dietetic practice group (Heather J. Baden, MS, RD, HB Nutrition, PC, Rye, NY); Women’s Healthdietetic practice group (Catherine L. Fagen, MA, RD, Miller Children’s Hospital, Long Beach, CA); and Erin Paris,MHS, RD, LDN (Consultant, Chicago, IL).

American Society of Nutrition: Nancy Butte, PhD (Baylor College of Medicine Children’s Nutrition ResearchCenter, Houston, TX); Kathleen Rasmussen, ScD, RD (Cornell University Division of Nutritional Sciences, Ithaca,NY).

Association Positions Committee Workgroup: Helen W. Lane, PhD, RD (chair); Katrina Holt, MPH, MS, RD; SallyAnn Lederman, PhD (content advisor).

May 2009 ● Journal of the AMERICAN DIETETIC ASSOCIATION 927