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Lecture 15: Pregnancy Lecture 15: Pregnancy
•• Gestational DevelopmentGestational Development
•• Early development and the Early development and the
placentaplacenta
•• Maternal/fetal conflictMaternal/fetal conflict
•• The Physiology of The Physiology of
PregnancyPregnancy
•• Pica eatingPica eating
•• Pregnancy SicknessPregnancy Sickness
The Behavioral Biology of Women-2006
22
Exercise during Pregnancy Exercise during Pregnancy
and Miscarriageand Miscarriage
0
4
8
12
16
20
Frequency of Miscarriage
Exercise Non-Exercise
(Clapp, 2002)
Stages of DevelopmentStages of Development
•• Conceptus Conceptus (morula & blastocyte)(morula & blastocyte)
•• EmbryoEmbryo
•• FetusFetus
•• EmbryogenesisEmbryogenesis
•• Embryonic PhaseEmbryonic Phase
•• Fetal PhaseFetal Phase
•• Weeks 0Weeks 0--22
•• Weeks 3Weeks 3--88
•• Weeks 9Weeks 9--3838
EmbryogenesisEmbryogenesis
•• Conceptus Conceptus
(morulla & blastocyte) (morulla & blastocyte)
•• First 14First 14--16 days = 16 days =
formation of an embryoformation of an embryo
EmbryogenesisEmbryogenesis
•• Conceptus Conceptus (morulla & blastocyte) (morulla & blastocyte)
•• First 14First 14--16 days = 16 days = formation of an embryoformation of an embryo
•• Histiotropic nutritionHistiotropic nutrition --relies on uterine secretions relies on uterine secretions for oxygen and metabolic for oxygen and metabolic substratessubstrates
EmbryogenesisEmbryogenesis
•• ConceptusConceptus
•• First 14First 14--16 days = 16 days = formation of an embryoformation of an embryo
•• Histiotropic nutrition Histiotropic nutrition --relies on uterine secretions relies on uterine secretions for oxygen and metabolic for oxygen and metabolic substratessubstrates
•• Differentiation into Differentiation into embryonic (inner cell embryonic (inner cell mass) and extramass) and extra--embryonic embryonic tissue (trophoblast)tissue (trophoblast)
33
Implantation: Actions of BlastocyteImplantation: Actions of Blastocyte
•• (1) Blastocyte establishes physical and (1) Blastocyte establishes physical and
nutritional contact with maternal nutritional contact with maternal
endometriumendometrium
Blastocyte Embedded in Uterine Lining
Haemotrophic Nutrition =
Nutrition from the maternal
blood supply
Establishment of the PlacentaEstablishment of the Placenta
•• Digestion of Digestion of
maternal tissue to maternal tissue to
release metabolic release metabolic
substratessubstrates
•• Primary Primary
Decidualization Decidualization
ReactionReaction
Species Differences in PlacentasSpecies Differences in Placentas
Human (discoid)Mouse, rabbit, bat Cat, seal, elephant ,bear (zonary)
Cow, sheep, giraffe (cotyledonary) Horse, whale, kangaroo (diffuse)
•• (2) Trophoblast (2) Trophoblast
starts to produce starts to produce
HCG (Human HCG (Human
Chorionic Chorionic
Gonadotrophin) Gonadotrophin)
to keep corpus to keep corpus
luteum aliveluteum alive
Implantation: Actions of Implantation: Actions of
BlastocyteBlastocyte
Expression of HCG during human pregnancyExpression of HCG during human pregnancy
44
Embryonic PhaseEmbryonic Phase
(Weeks 3(Weeks 3--8)8)
•• Formation of basic body planFormation of basic body plan
•• Development of all major organ systemsDevelopment of all major organ systems
5 Weeks
6 Weeks
7 Weeks
Fetal PhaseFetal Phase
(Weeks 9(Weeks 9--38)38)
•• Growth and further development of body Growth and further development of body
tissues and organs.tissues and organs.
55
9 Weeks
13 Weeks
21 Weeks
Russell at 3 monthsRussell at 3 months
THE PHYSIOLOGY OF THE PHYSIOLOGY OF
PREGNANCYPREGNANCY
Corpus Luteum
66
Corpus LuteumCorpus Luteum
•• Produces increasing amounts of Produces increasing amounts of
progesteroneprogesterone
•• Synthesizes estrogenSynthesizes estrogen
•• Important for production until 6Important for production until 6--
7 weeks of pregnancy7 weeks of pregnancy
•• If embryo canIf embryo can’’t maintain hormone t maintain hormone
production often results in miscarriage at production often results in miscarriage at
this time.this time.
•• Helps maintain early pregnancyHelps maintain early pregnancy
The Role of the FetusThe Role of the Fetus
The Placenta The Placenta -- ““baby sidebaby side”” The Placenta The Placenta -- ““mother sidemother side””
Human Haemomonochorial Human Haemomonochorial
PlacentaPlacenta
•• ExtraExtra--embryonic embryonic
tissue, containing fetal tissue, containing fetal
blood vessels, blood vessels,
penetrates deep into penetrates deep into
maternal tissuematernal tissue
77
Human Haemomonochorial Human Haemomonochorial
Placenta Placenta -- Terminal villusTerminal villus
•• Tips of capillaries Tips of capillaries
form tortuous loops form tortuous loops ----
slowing blood flow slowing blood flow
and allowing for and allowing for
exchange of exchange of
metabolites with metabolites with
maternal blood.maternal blood.
Human Haemomonochorial Human Haemomonochorial
PlacentaPlacenta
•• Maternal spiral artery Maternal spiral artery
ejects blood into ejects blood into
‘‘maternal blood maternal blood
spacespace’’
Pregnancy ConflictsPregnancy Conflicts HamiltonHamilton’’s Rules Rule
You are related to yourself by 100%, You are related to yourself by 100%,
to your children your siblings and to your children your siblings and
your parents by 50%, etc.your parents by 50%, etc.
88
Pregnancy Pregnancy ““ConflictsConflicts””
•• Paternal genes will be Paternal genes will be
selected to increase the selected to increase the
transfer of nutrients to transfer of nutrients to
the fetusthe fetus
•• Maternal genes will be Maternal genes will be
selected to limit selected to limit
transfers in excess of transfers in excess of
some maternal some maternal
optimumoptimum
Haig, 1993
Monogenetic Mouse Embryos
Control Gynogenetic Androgenetic
Embryo
Yolk Sac
Trophoblast
Supporting EvidenceSupporting Evidence•• Trophoblast invades maternal Trophoblast invades maternal
endometrium and remodels the endometrium and remodels the
spiral arteries so they are spiral arteries so they are
unable to constrictunable to constrict
Supporting EvidenceSupporting Evidence•• Trophoblast invades maternal Trophoblast invades maternal
endometrium and remodels the endometrium and remodels the
spiral arteries so they are spiral arteries so they are
unable to constrictunable to constrict
–– Fetus gains access to motherFetus gains access to mother’’s s
arterial blood & mother canarterial blood & mother can’’t t
change nutrient content of bloodchange nutrient content of blood
Supporting EvidenceSupporting Evidence•• Trophoblast invades maternal Trophoblast invades maternal
endometrium and remodels the endometrium and remodels the
spiral arteries so they are spiral arteries so they are
unable to constrictunable to constrict
–– Fetus gains access to motherFetus gains access to mother’’s s
arterial blood & mother canarterial blood & mother can’’t t
change nutrient content of bloodchange nutrient content of blood
–– Volume of blood reaching Volume of blood reaching
placenta not under maternal placenta not under maternal
controlcontrol
Supporting EvidenceSupporting Evidence•• Trophoblast invades maternal Trophoblast invades maternal
endometrium and remodels the endometrium and remodels the
spiral arteries so they are spiral arteries so they are
unable to constrictunable to constrict
–– Fetus gains access to motherFetus gains access to mother’’s s
arterial blood & mother canarterial blood & mother can’’t t
change nutrient content of bloodchange nutrient content of blood
–– Volume of blood reaching Volume of blood reaching
placenta not under maternal placenta not under maternal
controlcontrol
–– Placenta is able to release Placenta is able to release
hormones directly into maternal hormones directly into maternal
circulationcirculation
99
Supporting EvidenceSupporting Evidence•• Trophoblast invades maternal Trophoblast invades maternal
endometrium and remodels the endometrium and remodels the
spiral arteries so they are spiral arteries so they are
unable to constrictunable to constrict
–– Fetus gains access to motherFetus gains access to mother’’s s
arterial blood & mother canarterial blood & mother can’’t t
change nutrient content of bloodchange nutrient content of blood
–– Volume of blood reaching Volume of blood reaching
placenta not under maternal placenta not under maternal
controlcontrol
–– Placenta is able to release Placenta is able to release
hormones directly into maternal hormones directly into maternal
circulationcirculation
•• High HCG levelsHigh HCG levels
Trend toward increased hormone Trend toward increased hormone
production?production?
•• Increase from 1 CGIncrease from 1 CGββ gene in gene in
Anthropoid Ancestor to 6 in humanAnthropoid Ancestor to 6 in human
•• Increase from 1 OIncrease from 1 O--linked sugar chain in linked sugar chain in
Anthropoid Ancestor to 4 in humanAnthropoid Ancestor to 4 in human
•• Increase from 1 CRE element in Increase from 1 CRE element in
Ancestral Ancestral αα promoter to 2 in humanpromoter to 2 in humanMaston, 2000
Increase in number of genes responsible for Increase in number of genes responsible for
hormonal production in Humanshormonal production in Humans
Hormonal Production in Hormonal Production in
the Placentathe Placenta
•• EstrogenEstrogen
•• ProgesteroneProgesterone
•• HCG (Human Chorionic Gonadotropin)HCG (Human Chorionic Gonadotropin)
•• HPL (Human Placental Lactogen)HPL (Human Placental Lactogen)
Fetoplacental UnitFetoplacental Unit
•• Placenta converts androgens from the Placenta converts androgens from the
adrenal gland of the fetus (as well as the adrenal gland of the fetus (as well as the
mother) into estrogen.mother) into estrogen.
Fetal Adrenal GlandsFetal Adrenal Glands
•• Fetal adrenal is the largest organ in the Fetal adrenal is the largest organ in the
babybaby’’s body (adult size) and produces 10 s body (adult size) and produces 10
times the amount of hormones as an adult.times the amount of hormones as an adult.
Estrogens and the Fetoplacental UnitEstrogens and the Fetoplacental Unit
•• Placenta converts androgens from the Placenta converts androgens from the
adrenal gland of the fetus (as well as the adrenal gland of the fetus (as well as the
mother) into estrogen.mother) into estrogen.
1010
Estrogen & the Fetoplacental UnitEstrogen & the Fetoplacental Unit
•• Placenta converts androgens from the Placenta converts androgens from the
adrenal gland of the fetus (as well as the adrenal gland of the fetus (as well as the
mother) into estrogen.mother) into estrogen.
•• Estrogen causes changes in the uterus, Estrogen causes changes in the uterus,
cervix, vagina and breasts and affects cervix, vagina and breasts and affects
metabolism.metabolism.
The Placenta: ProgesteroneThe Placenta: Progesterone
•• Takes over progesterone production from Takes over progesterone production from
the Corpus Luteumthe Corpus Luteum
The Placenta: ProgesteroneThe Placenta: Progesterone
•• Takes over progesterone Takes over progesterone
production from the Corpus production from the Corpus
LuteumLuteum
•• Levels are 10 times as high as Levels are 10 times as high as
before fertilizationbefore fertilization
The Placenta: ProgesteroneThe Placenta: Progesterone
•• Takes over progesterone production from Takes over progesterone production from
the Corpus Luteumthe Corpus Luteum
•• Levels are 10 times as high as before Levels are 10 times as high as before
fertilizationfertilization
•• Keeps uterus from contractingKeeps uterus from contracting
The Placenta: ProgesteroneThe Placenta: Progesterone
•• Takes over progesterone Takes over progesterone
production from the Corpus production from the Corpus
LuteumLuteum
•• Levels are 10 times as high as Levels are 10 times as high as
before fertilizationbefore fertilization
•• Keeps uterus from contractingKeeps uterus from contracting
•• Maintains blood vessels and Maintains blood vessels and
glands in uterine liningglands in uterine lining
The Placenta: HCGThe Placenta: HCG
•• Keeps Corpus Keeps Corpus
Luteum from Luteum from
shrinking.shrinking.
1111
The Placenta: HCGThe Placenta: HCG
•• Keeps Corpus Keeps Corpus
Luteum from Luteum from
shrinking.shrinking.
•• Production rises Production rises
steeply after steeply after
implantationimplantation
The Placenta: HPLThe Placenta: HPL
(Human Placental Lactogen)(Human Placental Lactogen)
•• Alters motherAlters mother’’s metabolism to make sugar s metabolism to make sugar
and proteins more available to fetusand proteins more available to fetus
The Placenta: HPLThe Placenta: HPL
•• Alters motherAlters mother’’s metabolism to make sugar s metabolism to make sugar
and proteins more available to fetusand proteins more available to fetus
•• Stimulates alveoli in motherStimulates alveoli in mother’’s breasts to s breasts to
develop and prepare for lactationdevelop and prepare for lactation
Hormonal changes during Pregnancy
Species Species
Differences in Differences in
Pregnancy Pregnancy
HormonesHormones
Hominoid Hominoid
Pregnancy Pregnancy
HormonesHormones
1212
Changes in the motherChanges in the mother Changes in UterusChanges in Uterus
•• Uterus grows to 500Uterus grows to 500--
1000 times in size1000 times in size
Changes in UterusChanges in Uterus
•• Uterus grows to Uterus grows to
500500--1000 times in 1000 times in
sizesize
•• New muscles fibers New muscles fibers
are produced.are produced.
Changes in SkeletonChanges in Skeleton
•• Increased spinal Increased spinal
curvaturecurvature
Changes in SkeletonChanges in Skeleton
•• Increased spinal Increased spinal
curvaturecurvature
•• Loosening of jointsLoosening of joints
Digestive SystemDigestive System
•• Uterus pushes intestines Uterus pushes intestines
& stomach up to the & stomach up to the
sideside
1313
Digestive SystemDigestive System
•• Uterus pushes intestines Uterus pushes intestines
& stomach up to the & stomach up to the
sideside
•• Shift in stomach causes Shift in stomach causes
change in angle of change in angle of
esophagusesophagus——heartburnheartburn
Digestive SystemDigestive System
•• Uterus pushes intestines Uterus pushes intestines
& stomach up to the & stomach up to the
sideside
•• Shift in stomach causes Shift in stomach causes
change in angle of change in angle of
esophagusesophagus——heartburnheartburn
•• High progesteroneHigh progesterone--
increased transit timeincreased transit time
Urinary Tract ChangesUrinary Tract Changes
•• Kidneys process 50% Kidneys process 50%
increase in wasteincrease in waste
Urinary Tract ChangesUrinary Tract Changes
•• Kidneys process 50% Kidneys process 50%
increase in wasteincrease in waste
•• Slower transit time Slower transit time
(smooth muscle slowed (smooth muscle slowed
down by progesterone)down by progesterone)
Urinary Tract ChangesUrinary Tract Changes
•• Kidneys process 50% Kidneys process 50%
increase in wasteincrease in waste
•• Slower transit time Slower transit time
(smooth muscle slowed (smooth muscle slowed
down by progesterone)down by progesterone)
•• Urinary Tract InfectionsUrinary Tract Infections
Urinary Tract ChangesUrinary Tract Changes
•• Kidneys process 50% Kidneys process 50%
increase in wasteincrease in waste
•• Slower transit time Slower transit time
(smooth muscle slowed (smooth muscle slowed
down by progesterone)down by progesterone)
•• Urinary Tract InfectionsUrinary Tract Infections
•• Compression of bladderCompression of bladder
1414
Changes during PregnancyChanges during Pregnancy
•• Gums may bleed Gums may bleed —— blood blood
vessel stimulation caused by vessel stimulation caused by
high estrogenhigh estrogen
Changes during PregnancyChanges during Pregnancy
•• Hemorrhoids and varicose veins Hemorrhoids and varicose veins
may developmay develop
•• Gums may bleed Gums may bleed —— blood blood
vessel stimulation caused by vessel stimulation caused by
high estrogenhigh estrogen
Heart ChangesHeart Changes
•• Heart works harder. Heart works harder.
Pulse increases by 10Pulse increases by 10--
15 beat/min15 beat/min
Heart ChangesHeart Changes
•• Heart works harder. Pulse Heart works harder. Pulse
increases by 10increases by 10--15 beat/min15 beat/min
•• Total cardiac output increased Total cardiac output increased
by 30%by 30%
Lung ChangesLung Changes
•• Lungs compressedLungs compressed
Lung ChangesLung Changes
•• Lungs compressedLungs compressed
•• Rib cage flares up and outRib cage flares up and out
1515
Lung ChangesLung Changes
•• Lungs compressedLungs compressed
•• Rib cage flares up and outRib cage flares up and out
•• Lungs bring in 40% more air.Lungs bring in 40% more air.
Changes During PregnancyChanges During Pregnancy
•• Separation of rectus abdominus muscle (diastesis)Separation of rectus abdominus muscle (diastesis)
Immune SystemImmune System
•• Placenta keeps Placenta keeps
babybaby’’s cells from s cells from
entering blood entering blood
streamstream
Immune SystemImmune System
•• Placenta keeps babyPlacenta keeps baby’’s s
cells from entering cells from entering
blood streamblood stream
•• Progesterone slows Progesterone slows
down antibody down antibody
productionproduction
Immune SystemImmune System
•• Placenta keeps babyPlacenta keeps baby’’s cells s cells
from entering blood streamfrom entering blood stream
•• Progesterone slows down Progesterone slows down
antibody productionantibody production
•• Baby produces surface Baby produces surface
repellent molecules that repellent molecules that
cross placenta and coat cross placenta and coat
mothermother’’s lymphocytess lymphocytes
Breast ChangesBreast Changes•• Increased engorgement Increased engorgement
caused by estrogen and caused by estrogen and
progesteroneprogesterone
•• TendernessTenderness
1616
Breast ChangesBreast Changes•• Increased engorgement Increased engorgement
caused by estrogen and caused by estrogen and
progesteroneprogesterone
–– TendernessTenderness
•• Size increaseSize increase
Breast ChangesBreast Changes•• Increased engorgement Increased engorgement
caused by estrogen and caused by estrogen and
progesteroneprogesterone
–– TendernessTenderness
•• Size increaseSize increase
•• Alveoli increaseAlveoli increase
Breast ChangesBreast Changes•• Increased engorgement Increased engorgement
caused by estrogen and caused by estrogen and
progesteroneprogesterone
–– TendernessTenderness
•• Size increaseSize increase
•• Alveoli increaseAlveoli increase
•• Striae visibleStriae visible
Breast ChangesBreast Changes•• Increased engorgement Increased engorgement
caused by estrogen and caused by estrogen and
progesteroneprogesterone
–– TendernessTenderness
•• Size increaseSize increase
•• Alveoli increaseAlveoli increase
•• Striae visibleStriae visible
•• NippleNipple--larger, darker, larger, darker,
more erectilemore erectile
Breast ChangesBreast Changes•• Increased engorgement Increased engorgement
caused by estrogen and caused by estrogen and
progesteroneprogesterone
–– TendernessTenderness
•• Size increaseSize increase
•• Alveoli increaseAlveoli increase
•• Striae visibleStriae visible
•• NippleNipple--larger, darker, larger, darker,
more erectilemore erectile
•• Areola darkensAreola darkens
Breast ChangesBreast Changes•• Increased engorgement Increased engorgement
caused by estrogen and caused by estrogen and
progesteroneprogesterone
–– TendernessTenderness
•• Size increaseSize increase
•• Alveoli increaseAlveoli increase
•• Striae visibleStriae visible
•• NippleNipple--larger, darker, larger, darker,
more erectilemore erectile
•• Areola darkensAreola darkens
•• Colostrum productionColostrum production
1717
The VaginaThe Vagina
•• VaginaVagina——increased blood flow increased blood flow
and softeningand softening
The VaginaThe Vagina
•• VaginaVagina——increased blood flow increased blood flow
and softening.and softening.
•• Walls thicken, looser, elongatesWalls thicken, looser, elongates
The VaginaThe Vagina
•• VaginaVagina——increased blood flow increased blood flow
and softening.and softening.
•• Walls thicken, looser, elongatesWalls thicken, looser, elongates
•• Increased dischargeIncreased discharge——acidic acidic
prevents infectionprevents infection
The VaginaThe Vagina
•• VaginaVagina——increased blood flow increased blood flow
and softening.and softening.
•• Walls thicken, looser, elongatesWalls thicken, looser, elongates
•• Increased dischargeIncreased discharge——prevents prevents
infectioninfection
•• Blood vessels in uterus, vagina Blood vessels in uterus, vagina
and pelvic area enlarge and and pelvic area enlarge and
increase in numberincrease in number
The CervixThe Cervix
•• Increases blood Increases blood
vessels and mucous vessels and mucous
glandsglands
The CervixThe Cervix
•• Increases blood Increases blood
vessels and mucous vessels and mucous
glandsglands
•• Formation of mucous Formation of mucous
plugplug
1818
Changes in SexualityChanges in Sexuality
•• Increased blood flow may result in Increased blood flow may result in
increased sexual arousalincreased sexual arousal
Changes in SexualityChanges in Sexuality
•• Increased blood flow may result in Increased blood flow may result in
increased sexual arousalincreased sexual arousal
•• May be more easily arousedMay be more easily aroused
Changes in SexualityChanges in Sexuality
•• Increased blood flow may result in Increased blood flow may result in
increased sexual arousalincreased sexual arousal
•• May be more easily arousedMay be more easily aroused
•• May have multiple orgasmsMay have multiple orgasms
Changes in PigmentationChanges in Pigmentation•• High levels of High levels of
melanocyte melanocyte
stimulating hormonestimulating hormone
Changes in PigmentationChanges in Pigmentation•• High levels of High levels of
melanocyte melanocyte
stimulating hormonestimulating hormone
•• Progesterone and Progesterone and
estrogen stimulate estrogen stimulate
pigment cellspigment cells
Changes in PigmentationChanges in Pigmentation•• High levels of High levels of
melanocyte melanocyte
stimulating hormonestimulating hormone
•• Progesterone and Progesterone and
estrogen stimulate estrogen stimulate
pigment cells pigment cells
•• ““Linea nigraLinea nigra””
1919
Changes in PigmentationChanges in Pigmentation•• High levels of High levels of
melanocyte melanocyte
stimulating hormonestimulating hormone
•• Progesterone and Progesterone and
estrogen stimulate estrogen stimulate
pigment cells pigment cells
•• ““Linea nigraLinea nigra””
•• ChloasmaChloasma——““mask mask
of pregnancyof pregnancy””
Changes in PigmentationChanges in Pigmentation•• High levels of High levels of
melanocyte melanocyte
stimulating hormonestimulating hormone
•• Progesterone and Progesterone and
estrogen stimulate estrogen stimulate
pigment cells pigment cells
•• ““Linea nigraLinea nigra””
•• ChloasmaChloasma——““mask mask
of pregnancyof pregnancy””
•• Nipples & Areola Nipples & Areola
darkendarken
Changes in PigmentationChanges in Pigmentation•• High levels of High levels of
melanocyte melanocyte
stimulating hormonestimulating hormone
•• Progesterone and Progesterone and
estrogen stimulate estrogen stimulate
pigment cells pigment cells
•• ““Linea nigraLinea nigra””
•• ChloasmaChloasma——““mask mask
of pregnancyof pregnancy””
•• Nipples & Areola Nipples & Areola
darkendarken •• Stretch marksStretch marks
Changes in PigmentationChanges in Pigmentation•• High levels of High levels of
melanocyte melanocyte
stimulating hormonestimulating hormone
•• Progesterone and Progesterone and
estrogen stimulate estrogen stimulate
pigment cells pigment cells
•• ““Linea nigraLinea nigra””
•• ChloasmaChloasma——““mask mask
of pregnancyof pregnancy””
•• Nipples & Areola Nipples & Areola
darkendarken
•• Stretch marksStretch marks
•• ““Vascular spidersVascular spiders””
on face, chest, armson face, chest, arms
Changes in Blood VolumeChanges in Blood Volume
•• Blood volume increases Blood volume increases
by 50by 50--100%100%
Changes in Blood VolumeChanges in Blood Volume
•• Blood volume increases Blood volume increases
by 50by 50--100%100%
–– Fills blood reservoir of Fills blood reservoir of
uterusuterus
–– Protects baby from drop Protects baby from drop
in b.p.in b.p.
–– Prepare mother for Prepare mother for
childbirthchildbirth
__ estrogen causes increase estrogen causes increase
in blood clotting factorsin blood clotting factors
2020
Sources of Weight GainSources of Weight Gain Charlotte BronteCharlotte Bronte
Studies of
Pregnancy
Sickness(NVP,
Nausea and
Vomiting
during
Pregnancy)
Pregnancy Sickness and Pregnancy Sickness and
Hormonal LevelsHormonal Levels
•• Higher levels of Higher levels of
HCG associated HCG associated
with increased with increased
nausea, vomiting, nausea, vomiting,
food aversion and food aversion and
smell aversionsmell aversion
•• Higher levels of HCG Higher levels of HCG associated with associated with increased nausea, increased nausea, vomiting, food aversion vomiting, food aversion and smell aversionand smell aversion
•• HCG peaks at 8HCG peaks at 8--10 10 weeks weeks ——parallels parallels pregnancy sicknesspregnancy sickness
Pregnancy Sickness and Pregnancy Sickness and
Hormonal LevelsHormonal Levels
•• Higher levels of HCG Higher levels of HCG associated with increased associated with increased nausea, vomiting, food nausea, vomiting, food aversion and smell aversionaversion and smell aversion
•• HCG peaks at 8HCG peaks at 8--10 weeks 10 weeks ——parallels pregnancy sicknessparallels pregnancy sickness
•• Increased Estrogen/Decreased Increased Estrogen/Decreased Progesterone ratio: Increased Progesterone ratio: Increased food avoidance, smell food avoidance, smell aversionaversion
Pregnancy Sickness and Pregnancy Sickness and
Hormonal LevelsHormonal Levels
2121
•• Higher levels of HCG associated Higher levels of HCG associated with increased nausea, vomiting, with increased nausea, vomiting, food aversion and smell aversionfood aversion and smell aversion
•• HCG peaks at 8HCG peaks at 8--10 weeks 10 weeks ——parallels pregnancy sicknessparallels pregnancy sickness
•• Increased Increased Estrogen/Decreased Estrogen/Decreased Progesterone ratio: Increased Progesterone ratio: Increased food avoidance, smell food avoidance, smell aversionaversion
•• Ratio not related to nausea or Ratio not related to nausea or vomitingvomiting
Pregnancy Sickness and Pregnancy Sickness and
Hormonal LevelsHormonal Levels
•• Higher levels of HCG associated Higher levels of HCG associated with increased nausea, vomiting, with increased nausea, vomiting, food aversion and smell aversionfood aversion and smell aversion
•• HCG peaks at 8HCG peaks at 8--10 weeks 10 weeks ——parallels pregnancy sicknessparallels pregnancy sickness
•• Increased Estrogen/Decreased Increased Estrogen/Decreased Progesterone ratio: Increased food Progesterone ratio: Increased food avoidance, smell aversionavoidance, smell aversion
•• Ratio not related to nausea or Ratio not related to nausea or vomitingvomiting
•• Decrease in symptoms with Decrease in symptoms with increased maternal ageincreased maternal age
Pregnancy Sickness and Pregnancy Sickness and
Hormonal LevelsHormonal Levels
Pregnancy Sickness HypothesisPregnancy Sickness Hypothesis
•• Food aversions, nausea Food aversions, nausea and vomiting of and vomiting of pregnancy sickness pregnancy sickness protect embryo against protect embryo against maternal ingestion of maternal ingestion of teratogens and teratogens and abortifacients that are abortifacients that are abundant in natural abundant in natural foods.foods.
Profet, 1990
Pregnancy Sickness HypothesisPregnancy Sickness Hypothesis•• Food aversions, nausea and Food aversions, nausea and
vomiting of pregnancy vomiting of pregnancy
sickness protect embryo sickness protect embryo
against maternal ingestion of against maternal ingestion of
teratogens and abortifacients teratogens and abortifacients
that are abundant in natural that are abundant in natural
foods.foods.
•• Lowering of the normal Lowering of the normal
human threshold of tolerance human threshold of tolerance
to toxins to compensate for to toxins to compensate for
extreme vulnerability of extreme vulnerability of
embryoembryo Profet, 1990
Pregnancy SicknessPregnancy Sickness
•• Foods that are safely Foods that are safely
ingested by adults ingested by adults
contain compounds contain compounds
that induce fetal that induce fetal
malformationsmalformations
Pregnancy SicknessPregnancy Sickness
•• Foods that are safely Foods that are safely
ingested by adults ingested by adults
contain compounds contain compounds
that induce fetal that induce fetal
malformationsmalformations
•• Women with Women with
pregnancy sickness pregnancy sickness
avoid foods that emit avoid foods that emit
cues associated with cues associated with
toxicitytoxicity
2222
Pregnancy SicknessPregnancy Sickness
•• Foods that are safely Foods that are safely
ingested by adults contain ingested by adults contain
compounds that induce compounds that induce
fetal malformationsfetal malformations
•• Women with pregnancy Women with pregnancy
sickness avoid foods that sickness avoid foods that
emit cues associated with emit cues associated with
toxicitytoxicity
•• Pregnancy sickness Pregnancy sickness
begins when the begins when the
embryo becomes embryo becomes
vulnerable to toxinsvulnerable to toxins
Pregnancy SicknessPregnancy Sickness
•• Foods that are safely ingested Foods that are safely ingested
by adults contain compounds by adults contain compounds
that induce fetal malformationsthat induce fetal malformations
•• Women with pregnancy Women with pregnancy
sickness avoid foods that emit sickness avoid foods that emit
cues associated with toxicitycues associated with toxicity
•• Pregnancy sickness begins when Pregnancy sickness begins when
the embryo becomes vulnerable the embryo becomes vulnerable
to toxinsto toxins
•• Olfactory system changes Olfactory system changes
during pregnancy in ways during pregnancy in ways
that promote selective that promote selective
avoidanceavoidance
Pregnancy SicknessPregnancy Sickness
•• Foods that are safely ingested by adults Foods that are safely ingested by adults
contain compounds that induce fetal contain compounds that induce fetal
malformationsmalformations
•• Women with pregnancy sickness avoid Women with pregnancy sickness avoid
foods that emit cues associated with foods that emit cues associated with
toxicitytoxicity
•• Pregnancy sickness begins when the Pregnancy sickness begins when the
embryo becomes vulnerable to toxinsembryo becomes vulnerable to toxins
•• Olfactory system changes during Olfactory system changes during
pregnancy in ways that promote pregnancy in ways that promote
selective avoidanceselective avoidance
•• Women with pregnancy sickness Women with pregnancy sickness
have better pregnancy outcomeshave better pregnancy outcomes
Pregnancy SicknessPregnancy Sickness
•• Foods that are safely ingested by adults Foods that are safely ingested by adults
contain compounds that induce fetal contain compounds that induce fetal
malformationsmalformations
•• Women with pregnancy sickness avoid foods Women with pregnancy sickness avoid foods
that emit cues associated with toxicitythat emit cues associated with toxicity
•• Pregnancy sickness begins when the embryo Pregnancy sickness begins when the embryo
becomes vulnerable to toxinsbecomes vulnerable to toxins
•• Olfactory system changes during pregnancy in Olfactory system changes during pregnancy in
ways that promote selective avoidanceways that promote selective avoidance
•• Women with pregnancy sickness have better Women with pregnancy sickness have better
pregnancy outcomespregnancy outcomes
•• Pregnancy sickness is crossPregnancy sickness is cross--culturalcultural
Test of Profet HypothesisTest of Profet Hypothesis
(Flaxman & Sherman, 2000)
Does morning sickness
protect the embryo by
causing pregnant women
to physically expel and
subsequently avoid foods
that contain teratogenic
and abortifacient
chemicals?
Test of Profet HypothesisTest of Profet Hypothesis• Symptoms peak when embryonic organogenesis is most susceptible to chemical disruption (weeks 6-18)
(Flaxman & Sherman, 2000)
2323
Test of Profet HypothesisTest of Profet Hypothesis• Symptoms peak when embryonic organogenesis is most susceptible to chemical disruption (weeks 6-18)
• Women who experience morning sickness are significantly less likely to miscarry than women who do not (9 of 9 studies)
(Flaxman & Sherman, 2000)
Test of Profet HypothesisTest of Profet Hypothesis• Symptoms peak when embryonic organogenesis is most susceptible to chemical disruption (weeks 6-18)
• Women who experience morning sickness are significantly less likely to miscarry that women who do not (9 of 9 studies)
• Women who vomit suffer fewer miscarriages than those who experience nausea alone
(Flaxman & Sherman, 2000)
Test of Profet HypothesisTest of Profet Hypothesis• Symptoms peak when embryonic organogenesis is most susceptible to chemical disruption (weeks 6-18)
• Women who experience morning sickness are significantly less likely to miscarry that women who do not (9 of 9 studies)
• Women who vomit suffer fewer miscarriages than those who experience nausea alone
• Many pregnant women have aversions to alcoholic and nonalcoholic (mostly caffeinated) beverages and strong-tasting vegetables, especially during the first trimester.
(Flaxman & Sherman, 2000)
Test of Profet HypothesisTest of Profet Hypothesis• Symptoms peak when embryonic organogenesis is most susceptible to chemical disruption (weeks 6-18)
• Women who experience morning sickness are significantly less likely to miscarry that women who do not (9 of 9 studies)
• Women who vomit suffer fewer miscarriages than those who experience nausea alone
• Many pregnant women have aversions to alcoholic and nonalcoholic (mostly caffeinated) beverages and strong-tasting vegetables, especially during the first trimester.
• However, greatest aversions are to meat, fish, poultry and eggs.
(Flaxman & Sherman, 2000)
CrossCross--Cultural Survey of Cultural Survey of
Morning Sickness IncidenceMorning Sickness Incidence
0
2
4
6
8
10
12
14
16
18
20
Number of Societies
NVP Observed NVP Never Observed
More meat
consumption
Less meat
consumption
(Flaxman & Sherman, 2000)
Pregnancy Sickness and Avoidance ofPregnancy Sickness and Avoidance of
Food Borne PathogensFood Borne Pathogens
(Flaxman & Sherman, 2000)
•• Pregnant women are immunosuppressed Pregnant women are immunosuppressed
and thus more vulnerable to serious and thus more vulnerable to serious
infections.infections.
•• Thus, pregnancy sickness evolved to avoid Thus, pregnancy sickness evolved to avoid
food borne parasites and pathogens that food borne parasites and pathogens that
might be dangerous.might be dangerous.
•• Differs from Profet by (1) focusing on Differs from Profet by (1) focusing on
toxins in meat not teratogens in plants (2) toxins in meat not teratogens in plants (2)
avoidance of infection not birth defectsavoidance of infection not birth defects
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