Physiology & Psychology
• Maternal physiological adaptations to
pregnancy
• The placenta
• Psychosocial adaptations
Physiology of Pregnancy
Goals:
1) Healthy mother
2) Appropriately grown, healthy fetus with low
risk for adult disease
Systematic Adjustments to
Pregnancy
•
•
•
•
Cardiovascular
Respiratory
Renal
GI
Cardiovascular Adaptations
• Heart rate increases
– 10-20%
– Begins as early as 5 weeks
– Peaks by 32 weeks
• Stoke volume increases
– 25-30%
– Peeks at 16-24 weeks
• Systemic Vascular Resistance decreases
–
–
–
–
20%
As early as 5 weeks
Result of vascular smooth muscle relaxation
Allows changes in cardiac output without increase in
arterial pressure
Cardiac output during three stages of gestation, labor,
and immediately postpartum compared with values of
nonpregnant women. All values were determined with
women in the lateral recumbent position.
Respiratory Adaptations
• 30% increased production of CO2
• 50% increase volume air and gas
exchange
• Increase in lung volume
• Decreased airway resistance
Renal Function Changes
• Renal blood flow
– Increases 50-80% by end of 1st trimester
– Decreases gradually to term
• Glomerular filtration rate
– Increases 40-50%
– Begins at 5 weeks, peaks at 9-16 weeks
– May decrease 15-20% from 36 weeks to
term
Mean glomerular filtration rate in healthy women over a
short period with infused inulin (solid line),
simultaneously as creatinine clearance during the inulin
infusion (broken line), and over 24 hours as endogenous
creatinine clearance (dotted line).
GI Adaptations
• Anatomic – growing uterus
• Hormonal
– Progesterone – relaxation of GI smooth
muscle
– Estrogen – increased tissue vascularity
Adjustments in Nutrient
Metabolism
• Goals
– support changes in anatomy and
physiology of mother
– support fetal growth and development
– maintain maternal homeostasis
– prepare for lactation
• Adjustments are complex and evolve
throughout pregnancy
General Concepts
1. Alterations include:
• increased intestinal absorption
• reduced excretion by kidney or GI tract
2. Alterations are driven by:
• hormonal changes
• fetal demands
• maternal nutrient supply
3. There may be more than one
adjustment for each nutrient.
4. Maternal behavioral changes augment
physiologic adjustments.
5. When adjustment limits are exceeded,
fetal growth and development are
impaired.
Birth weight of 11 children born to a poor woman in
Montreal; 8 children were born before receiving nutritional
counseling and food supplements from the Montreal Diet
Dispensary and 3 children were born afterward.
6. The first half of pregnancy is a time of
preparation for the demands of rapid
fetal growth in the second half.
7. Alterations in maternal
physiology facilitate transfer of
nutrients to the fetus.
Nitrogen Balance (g/day)
Source
Early
pregnant
Late
pregnant
Nonpregnant
Intake
12.03
12.19
11.88
Fecal loss
-0.82
-0.92
-0.64
Urinary loss
-10.52
-9.02
-10.56
Integumental
loss
-0.14
-0.18
-0.21
0.56
2.10
0.46
Retention
Hormonal Adjustments
• Changes in over 30 different hormones have been
detected in pregnancy
• Estrogens: increase significantly in pregnancy,
influence carbohydrate, lipid, and bone metabolism
• Progesterone: relaxes smooth muscle and causes
atony of GI and urinary tract
• Human Placental Lactogen (hPL): stimulates
maternal metabolism, increases insulin resistance,
aids glucose transport across placenta, stimulates
breast development
Late gestation is characterized by:
– Anti-insulinogenic and lipolytic effects of
Human chorionic somatomammotropin,
prolactin, cortisol, glucagon
Which Results in:
– Glucose intolerance, insulin resistance,
decreased hepatic glycogen, mobilization
of adipose tissue
Maternal Nutrient Levels
• Increased triglycerides
• Increased cholesterol
• Decreased plasma amino acids &
albumin
Lipids
Total triglycerides
Total cholesterol
VLDL cholesterol
Non
pregnant
60
170
10
Early
Late
pregnancy pregnancy
75 to 100
210
175 to 200
250
10
25
LDL cholesterol
105
100 to 125
150
HDL cholesterol
55
55 to 75
65
Maternal Albumin
Week of Gestation
10
20
30
40
Serum Albumin g/L
32
29
28
28
Maternal Plasma volume
increases ~ 40%
• range 30-50%
• nutrient concentration declines due to
increased volume, but total amount of
vitamins and minerals in circulation
actually increases.
Mean hemoglobin concentrations ( — ) and 5th and 95th ( —
percentiles for healthy pregnant women taking iron supplements
)
Embryonic and Placental
Development
• http://www.youtube.com/watch?v=UgT5rU
Q9EmQ
• http://www.youtube.com/watch?v=jo3NjAp
FSQE
• http://www.youtube.com/watch?v=YJL9roi
1LbM&feature=related
Embryonic Development
• In early gestation Embryo is nourished
by secretions of the oviduct and uterine
endometrial glands
• Uterine secretions include growth
factors (e.g. TNFa, epidermal growth
factor) that promote placental growth
• Growth trajectories of both placenta and
fetus are established early & have
lifelong consequences
Nutrient Availability & Maternal
Metabolic Status
• Blastocyst development & implantation are
reduced
– diabetic mothers
– animal models with insufficient nutrients
• Poorly nourished women and obese women
at risk for aberrations in embryonic and
placental development
– Congenital anomalies
– Adverse outcomes later in pregnancy (e.g.
preeclampsia)
The Placenta
• 10-12 weeks is the period of
placentation
• Rapid early growth prepares way for
fetal growth
• Trophoblast cells use same molecular
mechanisms as tumors, but are highly
regulated and controlled
Placental Functions
• Maintains immunological distance
between mother and fetus
• Special endocrine organ: “transient
hypothalamo-pituitary-gonadal axis”
• Responsible for exchange of nutrients,
gases & metabolic waste products
between maternal and fetal circulation
Placental Architecture
• Maternal and fetal blood do not mix:
“placental barrier”
– Fetal blood flows through capillary
networks within highly branched terminal
chorionic villi
– Maternal blood flows through intervillous
space
• Uterine arteriols bring blood in
• Uterine venules drain blood
Placental
vasculature
Reproduced with permission from: Vander, AJ,
Sherman, JH, Luciano, DS. Human Physiology, 6th
ed, McGraw-Hill, Inc 2001. p. 679. Original Figure
.
19-24. Copyright © 2001 McGraw-Hill
©2007 UpToDate® • www.uptodate.com
Licensed to Univ Of Washington
Placental Capacity Increases
During Gestation
• Expression of transporters increases
• The “brush border” microvilli develop to:
– increase surface area
– impede maternal blood flow
• Flow through the placenta at term is 500
ml/minute
Mechanisms of Nutrient Transfer Across
the Placenta
Maternal to Infant Nutrient Transportation
Across The Placenta
Substance
Primary Mechanism
Water, electrolytes, urea, free fatty Passive diffusion
acids, steroids, fat soluble vitamins
Glucose
Facilitated diffusion
Amino acids, water soluble
vitamins, calcium, iron, iodine
Active transport
Globulins, phospholipids,
lipoproteins
Pinocytosis and endocytosis
Water, electrolytes
Bulk flow (due to changes in
hydrostatic or osmotic forces),
solvent drag
Fetal to Maternal Transport
• Carbon dioxide
• Water & urea
• Signaling Molecules: Hormones,
cytokines, others
Factors Affecting Placental
Transfer
• Placental size
• Diffusion distance –
– diabetes and infection cause edema of the villi
– distance decreases as pregnancy progresses and
fetal needs increase
• Maternal-placental blood flow
• Blood saturation with gases and nutrients
Factors Affecting Placental
Transfer (cont)
• Maternal-placental metabolism of the
substance
• Disorders in expression or activity of
nutrient transporters
• Maternal use of tobacco, cocaine,
alcohol
Metabolic Functions of the
Placenta
• Glycogen synthesis: from maternal glucose &
stored
• Cholesterol synthesis: placental cholesterol
is precursor for placental progesterone and
estrogens
• Protein production: rises to 7.5 g per day at
term
• Lactate: produced in large quantities and
needs to be removed
Endocrine Functions
• Placenta Produces Peptide hormones
– Human Chorionic gonodotrophin (hCG) - secreted
early and helps to maintain synthesis of
progesterone
– Human placental lactogen (hPL): increase supply
of glucose to future by decreasing maternal stores
of fatty acids by altering maternal secretion of
insulin
– Insulin-like growth factors (IGF): IGF signaling
system is a major regulator of growth in fetus and
infant
Endocrine Functions
• Steroid hormones
– Progesterone: produced by placenta,
needed to maintain non-contractile uterus
– Estrogen: produced by placenta drives
many processes in pregnancy
• Glucocorticoids: placenta regulates fetal
exposure
Emerging Understandings
• Cytokines & Inflammatory molecules are
produced by the placenta as well as
adipocytes
• Adverse outcomes in obese women may be
associated with imbalances due to
overproduction from both sources
• “In pregnancy complicated with obesity or
DM, continuous adverse stimulus is
associated with dysregulation of metabolic,
vasular and inflammatory pathways.”
The Known and Unknown of Leptin in
Pregnancy (Hauguel-de-Mouzon, Am J Obstet Gynecology, 2006)
• Maternal plasma leptin levels rise in
pregnancy
• Leptin is produced by placenta
• Overproduction of placental leptin is seen
with diabetes and htn in pregnancy
• Umbilical leptin levels are biomarker of fetal
adiposity
• “Leptin may be sensitive to maternal energy
status and coordinate metabolic response
accordingly.” (King, Ann Rev Nutr, 2006)
Maternal Undernutrition Influences
Placental-Fetal Development
(Belkacemi et al. Bio Repro. 2010)
• What nutritional factors are associated
with placental “plasticity?”
• What are the long term impacts of
placental insufficiency?
• What are the implications for practice?
Psychology of Pregnancy
• Psychosocial adaptation
– Process over time
– Prerequisite for developing parental
identify and behavior
• Factors that impact psychosocial
adaptation
– Pregnancy intendedness
– Stress & depression
Why do we care in terms of
nutrition?
• Stress interferes with ability to achieve
developmental tasks
• Developmental tasks key to ability of
mother to take care of herself and her
baby nutritionally.
Maternal Focus
Trimester
1
I’m pregnant!
2
There’s a BABY…..
3
I’m going to be a MOM
Developmental Tasks of
Pregnancy (Rubin, 1984)
• Seeking safe passage for herself and
her child through pregnancy, labor, and
delivery.
• Ensuring the acceptance by significant
persons in her family of the child she
bears.
• Binding-in to her unknown baby.
• Learning to give of herself.
Ensuring Safe Passage
• Care and knowledge seeking behaviors
• Concerns
– T1: own well-being
– T2: focus shifts to fetus/baby
– T3: surviving labor and birth
• Goal: personal survival and safe birth
of healthy baby
Seeking Acceptance/Support for
Self and Baby
• Re-defining relationships with
– Spouse/partner
– Family of origin
– Friends
– New social support networks
• Goal: ensure a place in the world for
herself, as a woman with a child, and
her baby
“Binding-in” to Unborn Child
• Attachment to fetus
• Process:
– Begins in childhood
– Intensifies in pregnancy with fantasizing about
unborn infant
– Well developed relationship by T3
– Birth – let go of being pregnant & adjusts to being
mother
– Integrates real baby
• Goal: maternal identity development
Giving of Oneself
• Willingness & ability to make personal
sacrifices for well-being of fetus/infant
• Goal: insure baby’s future well-being
What about Dad? Psychosocial and mental health issues
for new fathers. (Condon, 2006. The Australian First Time Fathers Study)
Tasks:
1. Developing an attachment to the fetus
2. Adjusting to the dyad becoming a triad
3. Conceptualizing the self as “father”
4. What type of father?
Unintended Pregnancy
At the time you became pregnant, did you want to
become pregnant then, did you want to wait until later, or
did you want no (more) children at all?
Births from Unintended Pregnancy in
WA State (PRAMS)
2000
2007
2010
Medicaid
56
54
51
Non-Medicaid
26
22
23
Total
38
36
36
http://www.doh.wa.gov/Portals/1/Documents/Pubs/950153_PerinatalIndicatorsforWashingtonResidents.pdf, May 2012
Unintended Pregnancy
Effects of pregnancy planning status
on birth outcomes and infant care
(Kost et al. Family Planning Perspectives, 1998)
Intended Mistimed Unwanted
LBW
5.1
6.5
9.7
SGA
9.5
11.3
13.7
Any
negative
outcomes
15.6
20.4
25.5
Ever
breastfed
59.9
46.6
36.1
Prevalence of Self-Reported Postpartum
Depressive Symptoms. MMWR, April 2008
• Overall prevalence ranged from 12-20%
in states.
• Characteristics associated with PDS:
• Maternal age
• Marital status
• Maternal education, medicaide
coverage
WA State Post-Partum Depression
• 2008: ~9% of mothers reported always or often feeling
down, depressed or hopeless, 10% reported always or
often having little interest or pleasure in doing things
(two questions combined identify subjects at higher risk
for post partum depression).
• 2008: 13% of women expressed experiencing
postpartum depression symptoms. More women on
Medicaid reported symptoms than women who did not
receive Medicaid.
• 2010:11% of women expressed feeling down,
depressed or sad. More women on Medicaid (14%)
reported symptoms than women who did not receive
Medicaid (8%).
http://www.doh.wa.gov/Portals/1/Documents/Pubs/950153_PerinatalIndicatorsforWashingtonResidents.pdf, May 2012.
WA State PDS Prevalence, 2004-2005
(MMWR, 2008)
Age
Race/ethnicity
Marital status
Education
< 20
> 30
White/non Hispanic
Black/non Hispanic
Hispanic
married
other
< 12
> 12
20 %
9%
11 %
20 %
14 %
12 %
17 %
19 %
11 %
Washington State PRAMS
WA State PRAMS