Validating a “Term BMI” using Mode of Delivery, Estimated Blood Loss, and Neonatal WeightValidating a “Term BMI” using Mode of Delivery, Estimated Blood Loss, and Neonatal Weight

Diana Garretto, MD & Erin Stevens, MD State University of New York at Stony Brook University Medical CenterDepartment of Obstetrics, Gynecology, & Reproductive Medicine

In non-pregnant populations, underweight is a BMI <18.5, normal weight is a BMI 18.5-24.9, overweight is a BMI 25-29.9, and obese is a BMI>30. The “Term BMI” was calculated by adding the respective IOM weight gain recommendations of each category to each pregnancy at term.

A single institution retrospective chart review was then performed of patients who delivered at term (>=37 weeks) from July 2009 to January 2010 was performed to validate the use of a Term BMI. Data included height, pre-pregnancy weight, maternal delivery weight, mode of delivery, neonatal weight, and estimated blood loss.

TablesTablesTablesTables

ConclusionsConclusions

Study DesignStudy Design

To validate using a “Term BMI” instead of pre-pregnancy BMI to evaluate for risk of blood loss, LGA fetus, and cesarean section on day of delivery.

ResultsResults

Based on the IOM guidelines, a patient would be considered underweight if the BMI at term was <23.5, normal weight if the BMI at term was 23.5-29.9, overweight if the BMI at term was 30-33.5 and obese if the BMI at term was >33.5. These were used as the “Term BMI” categories.

1,031 patients met inclusion criteria. The data was analyzed using the Jonckheere-Terpstra Test. There was a significant increase in risk of cesarean section with increasing BMI in both the pre-pregnancy and Term BMI groups (Table 1). There was also a significant increase in estimated blood loss (Table 2) and neonatal weight (Table 3) with increasing BMI in both the pre-pregnancy and Term BMI groups.

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Using the “Term BMI” at the time of delivery may be an easier and more accurate way to objectively assess risks of obesity at term than pre-pregnancy weight or BMI alone.

The “Term BMI” allows calculation of a woman’s BMI the actual day of delivery and can help to predict complications associated with delivery including mode of delivery, neonatal weight, and estimated blood loss.

BMIC-Section

RatePre-

pregnancy

C-Section Rate Term

Normal Weight 27.79% 28.64%

Overweight 31.87% 28.93%

Obese 42.27% 40.5%

P-value 0.0026 0.0033

BMIEBL Mean

Pre-pregnancy

EBL Mean Term

Normal weight 589 573

Overweight 636 627

Obese 727 731

P-value 0.0002 <0.0001

BMINeonatal

weight MeanPre-

pregnancy

Neonatal weight Mean

Term

Normal weight 3405 3366

Overweight 3420 3436

Obese 3466 3510

P-value 0.0168 <0.0001

Table 1Table 1

Table 2Table 2

Table 3Table 3

Among non-pregnant women age 20-39, 25% of them are overweight and 28% are obese, and 6% have a BMI >= to 40. Issues begin with pre-conception with infertility etc to antepartum issues including GDM and anomalies through intrapartum problems. Postpartum issues include increased risk for venous thrombosis, etc.

ObjectiveObjective

BackgroundBackground