1. Lecture 2 - 2005 Physiological adaptations to pregnancy Psychology
Energy
Weight Gain

2. Physiology of Pregnancy

3. Systematic Adjustments to Pregnancy
Cardiovascular
Respiratory
Urinary

4. 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.

5. Change in cardiac outline that occurs in pregnancy
Change in cardiac outline that occurs in pregnancy. The light lines represent the relations between the heart and thorax in the nonpregnant woman, and the heavy lines represent the conditions existing in pregnancy. These findings are based on x-ray findings in 33 women.

6. TABLE 8-4. Ventilatory Function in Pregnant Women Compared with the Postpartum Period
During Pregnancy
Factor
10 Weeks
24 Weeks
36 Weeks
Postpartum 6-10 Weeks
Respiratory rate
15-16 16
16-17
Tidal volume (mL)
650
700
550a
Minute ventilation (L) —
10.5
7.5a
Vital capacity (L)
3.8
3.9
4.1
Inspiratory capacity (L)
2.6
2.7
2.9
2.5
Expiratory reserve volume (L)
1.2
1.3
Residual volume (L)
1.1
1.0
1.2a
a Significant increase or decrease compared with pregnant women.

7. 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).

8. King J. Physiology of pregnancy and nutrient metabolism
King J. Physiology of pregnancy and nutrient metabolism. Am J Clin Nutr 2000;71 (suppl):1218S-25S

9. 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

10. General Concepts 1. Alterations include: 2. Alterations are driven by:
increased intestinal absorption
reduced excretion by kidney or GI tract
2. Alterations are driven by:
hormonal changes
fetal demands
maternal nutrient supply

11. 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.

12. 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.

13. 6. The first half of pregnancy is a time of preparation for the demands of rapid fetal growth in the second half

14. 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

15. 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

17. Mean (±SEM) plasma lipid concentrations (mg/dL) throughout gestation (n = 42) and during the luteal (I) and follicular (II) phases postpartum (p.p.; n = 23). The dashed lines represent the mean values of the control group (n = 24). (FC = free cholesterol; PL = phospholipids; TC = total cholesterol; TG = triglycerides.)(

18. Maternal Nutrient Levels
Increased triglycerides
Increased cholesterol
Decreased plasma amino acids & albumin
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.

20. Mean hemoglobin concentrations (  —  ) and 5th and 95th (  —  ) percentiles for healthy pregnant women taking iron supplements

21. Maternal Nutrient Levels

22. Nitrogen Balance (g/day)

23. Alterations in maternal physiology facilitate transfer of nutrients to the fetus.

25. The Placenta
Early gestation (10-12 weeks) is the period of placentiation
Fetus is nourished by secretions of uterine endometrial glands in early gestation
Placenta is a metabolically active tissue
Responsible for exchange of nutrients, gases & metabolic waste products between maternal and fetal circulation
Glucose is predominant energy source for both placenta and fetus

26. 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

27. 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

28. Mechanisms of Nutrient Transfer Across the Placenta

29. Maternal to Infant Nutrient Transportation Across The Placenta

30. Fetal to Maternal Transport
Carbon dioxide
Water & urea
Hormones

32. 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

33. 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

34. Psychology of Pregnancy
Psychosocial tasks
Rubin
Leaderman’s tasks
Fathers
Cultural awareness

35. 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.

36. Lederman, RP. Psychosocial Adaptation in Pregnancy, 2nd Ed. 1996
Developmental Tasks of Pregnancy
acceptance of pregnancy
identification with motherhood role
relationship to the mother
relationship to the husband/partner
preparation for labor
processing fear of loss of control & loss of self esteem in labor

37. Psychosocial adjustment during pregnancy: the experience of mature gravidas (Stark, JOGNN, 1997)
N=64 older gravidas (> 35), 46 younger gravidas (< 32) in third trimester
Lederman prenatal self evaluation questionnaire - examines conflicts for 7 steps
In general conflicts about maternal role were similar in both groups
Older gravidas had less concern about fear of helplessness and loss of control in labor - regardless of parity

38. Developmental Tasks of Fatherhood
Accepting the pregnancy
Identifying the role of father
Reordering relationships
Establishing relationship with his child
Preparing for the birth experience

39. Laboring for Relevance: Expectant and New Fatherhood (Jordan, Nursing Research, 1990)
N=56 expectant fathers followed prospectively
“Tasks”
grappling with the reality of the pregnancy and child
struggling for recognition as a parent from mother, coworkers, friends, family baby and society
plugging away at the role-making of involved fatherhood

40. Jordan, cont. Identified concerns:
Men not recognized as parents but as helpmates and breadwinners
Men felt excluded from childbearing experience by mates, health care providers, and society
Fathers felt that they had no role models for active and involved parenthood

41. Energy Requirements in Pregnancy
Energy costs of pregnancy:
increased maternal metabolic rate
fetal tissues
increase in maternal tissues

42. RDA for Energy in Pregnancy - Old
Energy cost of pregnancy = 80,000 kcal (Hytten and Leitch, 1971)
maternal gain of 12.5 kg
infant weight of 3.3 kg
80,000/250 days (days after the first month)
Additional 300 kcal per day recommended in second and third trimester
total of 2,500 for reference woman

43. DRI for Energy - New

45. Estimated Energy Requirement
Average dietary energy intake that is predicted to maintain energy balance in a healthy adult of a defined age, gender, weight, height, level of physical activity consistent with good health.
In children, pregnant and lactating women the EER is taken to include the needs associated with deposition of tissues or secretion of milk

52. DRI for Energy in Pregnancy - 2002

53. BEE: Basal Energy Expenditure
Increases due to metabolic contribution of uterus and fetus and increased work of heart and lungs.
Variable for individuals

55. Growth of Maternal and Fetal Tissues
Still based on work of Hytten
Based on IOM weight gain recommendations

58. Longitudinal Data from DLW Database
Median TEE (total energy expenditure) change from non-pregnant was 8 kcal/gestational week.
TEE changes little in first trimester.

60. Variations in Energy Requirements
Body size - especially lbm
Activity:
most women decrease activity in last months of pregnancy if they can
increased energy cost of moving heavier body
BMR
rises in well nourished women (27%)
rises less or not at all in women who are not well nourished
-Diet Induced Thermogenesis?

61. N=58, initially recruited, ages 18-40
Evidence of energy sparing in Gambian women during pregnancy: a longitudinal study using whole-body calorimetry (AJCN, 1993)
N=58, initially recruited, ages 18-40
25 became pregnant
21 participated in study protocols
9 completed BMR and 24 hour energy expenditure
12 completed BMR
Adjusted for seasonality, weight loss expected during wet season

62. Poppitt et al., cont. Mean maternal prepregnancy weight was 52 kg
Mean prepregnancy BMI was
Mean birthweight was
Mean gestational length was 39.4
Mean weight gain was 6.8 kg
Mean fat gain was 2.0 kg at 36 weeks

63. Poppitt et al., cont. BMR fell in early pregnancy
Values per kg lbm remained below baseline for duration of pregnancy
Individual variation was high

65. Poppitt et al., cont.
Energy sparing mechanisms may act via a suppression of metabolism in women on habitually low intakes.
This maintains positive balance in the mother and protects the fetus from growth retardation

66. Prentice and Goldberg. Energy Adaptations in human pregnancy: limits and long-term consequences. Am J Clin Nutr ;71(supple):1226S-32S.

68. Longitudinal assessment of energy balance in well-nourished, pregnant women (Koop-Hoolihan et al, AJCN, 1999)
N=16, SF area
10 became pregnant
BMI range was 19-26
Mean weight gain at 36 weeks was
Mean birth weight was 3.6

69. Koop-Hoolihan, cont
Protocol: 5 times before pregnancy, 3 times during, once 4-6 weeks postpartum
RMR (resting metabolic rate/metabolic cart)
DIT (diet induced thermogenesis/metabolic cart)
TEE (total energy expenditure/doubly labeled water)
AEE (activity energy expenditure/difference between TEE and RMR)
EI (energy intake/3 day food records)
Body composition - densitometry, tbw, bmc with absorptiometry

70. Koop-Hoolihan, cont
Women with the largest cumulative increase in RMR deposited the least fat mass (this was the only prepregnant factor that predicted fat mass gain)
In all indices there was large individual variation
Average total energy cost of pregnancy was similar to work of Hytten and Leitch (1971)
Food intake records indicated 9% increase in kcals with pregnancy, but highly variable

71. Energy in Pregnancy (Roy Pitkin, AJCN, 1999)
Koop-Hoolihan study design was “Impeccable.”
Women meet increase energy demands of pregnancy in a variety of ways - increased intakes, decreased activity or DIT, limited fat storage.
RDA?

72. Energy in Pregnancy (Roy Pitkin, AJCN, 1999)
“A prudent course seems to be to permit considerable latitude in energy intake recommendations on the basis of individual preferences and to monitor weight gain carefully, making adjustments in energy intake only in response to the normal pattern of gain.”

73. Maternal Obesity Rates of obesity are increasing world-wide
Obesity before pregnancy is associated with risk of several adverse outcomes

74. Prepregnancy weight and the risk of adverse pregnancy outcomes (Cnattingius et al, NEJM, 1998)
N=167,750 in Sweden, Norway, Finland, or Iceland who gave birth to singleton babies in 1992 and 1993.
Outcome = late fetal death
Adjusted for maternal age, parity, education, smoking, height and living with father

75. Prepregnancy weight and the risk of adverse pregnancy outcomes (Cnattingius et al, NEJM, 1998)

76. Prepregnancy weight and the risk of adverse pregnancy outcomes (Cnattingius et al, NEJM, 1998)

77. Cnattingius et al, Discussion
Even lean women were probably well nourished in this cohort. Results in other countries may be different.
Maternal overweight may be major factor in SES differences in perinatal morbidity and mortality
Impetus toward developing strategies to reverse trends toward increasing body weight

78. Perinatal Outcomes of Obese Women: A Review of the Literature (Morin, JOGNN, 1998)
Extensive Review of Medine and CINAHL
Definitions of obesity vary, but IOM says obesity = BMI > 29

79. Diagnosis
Menses tend to be irregular and pelvic exams and ultrasound exams may be difficult
AFP values may be lower than norms due to increased plasma volume
Blood pressure monitoring may be difficult

80. Antepartum Outcomes
Higher rates of NTD even with folic acid supplementation (RR = 3.0 in one study)
Increased risk for both chronic and pregnancy induced hypertension
Increased risk for severe preeclampsia (BMI < 32.3, risk was 3.5 times that of controls)
Increased risk for both GDM, IDD and NIDD.
Increased twining
Increased UTI

81. Labor and Birth Outcomes
Increased incidence of both primary (31% vs 8.6%) and secondary cesarean births - often associated with fetal macrosomia and/or failed induction.
Operative times are longer
Increased incidence of blood loss during surgery
? Differences in responses to anesthesia (greater spread/higher levels)

82. Postpartum Outcomes Increased risk for wound and endometrial infection
Increased prevalence of urinary incontinence

83. Infant Outcomes
Large infants - effect is independent of maternal diabetes
Increased infant mortality - RR for infants born to obese women was 4.0 compared to women with BMI < 20

84. Cost Costs were 3.2 times higher for women with BMI > 35
Longer hospitalizations

85. Increased Risk in Obese Women
Maternal Obesity and Pregnancy Outcomes: Castro & Alvina, Curr Opin obstet Gynecol, 2002
Increased Risk in Obese Women
Pre-eclampsia
2 to 4 times as high
Diabetes
3 times as high
Postpartum hemorrhage
70% increase
Infant shoulder dystocia
2 times as high
Thromboembolic disease
Respiratory complications

86. IOM Recommendations
Institute of Medicine. Nutrition during pregnancy, weight gain and nutrient supplements. Report of the Subcommittee on Nutritional Status and Weight Gain during Pregnancy, Subcommittee on Dietary Intake and Nutrient Supplements during Pregnancy, Committee on Nutritional Status during Pregnancy and Lactation, Food and Nutrition Board. Washington, DC: National Academy Press, 1990

87. Weight-for-height category Recommended total gain (kg)
Recommended total weight gain in pregnant women by prepregnancy BMI (in kg/m2)
Weight-for-height category Recommended total gain (kg)
Low (BMI <19.8) –18
Normal (BMI 19.8–26.0) 11.5–16
High (BMI >26.0–29.0)2 7–11.5
Adolescents and black women should strive for gains at the upper end of the recommended range. Short women (<157 cm) should strive for gains at the lower end of the range. The recommended target weight gain for obese women (BMI >29.0) is 6.0.

88. Cogswell M, Serdula M, Hungerford D, Yip R
Cogswell M, Serdula M, Hungerford D, Yip R. Gestational weight gain among average-weight and overweight women—what is excessive? Am J Obstet Gynecol 1995;172:705–12

89. Incidence of adverse outcomes for 6690 pregnancies in San Francisco
Parker J, Abrams B. Prenatal weight gain advice: an examination of the recent prenatal weight gain recommendations of the Institute of Medicine. Obstet Gynecol 1992;79:664–9

90. Percentage of US women with normal prepregnancy weights who retained >9 kg 10–24 mo postpartum relative to prepregnancy weight
(Parker J, Abrams B. Differences in postpartum weight retention between black and white mothers. Obstet Gynecol 1993;81:768– 74)

91. Rates of Weight Gain: T2 and T3
Underweight women: 0.5 kg per week
Normal weight women: 0.4 kg per week
Overweight women: 0.3 kg per week

92. Postpartum Weight
IOM (1990) concluded that childbearing is associated with average weight gain of 1kg.
There is a large variation in differences between prepregnant weight and weight at 6 to 12 months postpartum (SD of 4.8 kg)
Analysis is confused by the tendency to gain weight with aging
Years between 25 and 34 are times when American women are most vulnerable to major weight gain

93. Postpartum Weight
Proportions of black women who have higher postpartum weights is higher in almost all studies.
Smoking is consistently related to less postpartum weight gain.

94. Predominantly white mothers in the Midwestern US
Predictors of weight gain at 6 and 18 months after childbirth: a pilot study (Walker, JOGNN, 1996)
N=88 at 6 months, 75 at 18 months
Out of about 300 who were sent a mailed questionnaire 6 and 18 months postpartum
Predominantly white mothers in the Midwestern US

95. Battery of tests including:
Predictors of weight gain at 6 and 18 months after childbirth: a pilot study (Walker, JOGNN, 1996)
Battery of tests including:
Health promoting lifestyle profile (48 items on exercise, nutrition, support self-actualization)
Categories of activity level
Weight locus of control scale (internal or external)
Self reported weight and height, method of delivery, method of infant feeding

96. Predictors of weight gain at 6 and 18 months after childbirth: a pilot study (Walker, JOGNN, 1996)

97. Walker, Results
At both 6 and 18 months, women who exceeded IOM wt. Gain recommendations had significantly higher pp weight increases.

99. Hicky, CA. Am J Clin Nutr. 2000;71(supple):1364S-70S.
Sociocultural and behavioral influences on weight gain during pregnancy
Hicky, CA. Am J Clin Nutr ;71(supple):1364S-70S.

100. Percent of Women Gaining < 7.3 kg

101. Characteristics of Women Associated with Inadequate Weight Gain
Lower education levels
Unmarried
Aged > 30 years
Smoking
Multiple parity

102. Possibly psycho-social stress and pregnancy intendedness (effects seem to differ by culture)
Low income women had twice the risk in NNS.
Migrant workers have higher risk in WIC populations

103. 1997 Review of Recommendations
Maternal Weight Gain: A Report of an Expert Work Group. Suitor, CW NCEMCH.

104. Recent Findings
Maternal water gain, which probably represents lean tissue, is a predictor of birthweight, fat gain is not predictive.
Effect size of energy intake on weight gain is modest.
When maternal weight gain is within IOM range, incidence of SGA & LBW is reduced

105. Recent Findings, cont.
Increasing prevalence of obesity in population calls for reexamination of effects of pregnancy weight gain & retention
Increased parity is associated with increased weight gain in adulthood.
Post delivery, African American women have greater weight retention than white women with the same pregnancy weight gain.

106. Recommendations for Practice
Promote use of IOM recommendations for rate of weight gain as well as total weight gain.
Promote strategies for weight gain within recommended ranges.
Promote healthy eating

107. Until more is known, two groups of special concern, Adolescents and African American women should be advised to stay within IOM ranges without either restricting weight gain or encouraging weight gain at the upper end of the range.

108. Multiple Births Optimal range of birthweight:
Twins: g at weeks
Triplets: g at weeks
Maternal weight gain of pounds with 1.5 pounds per week during second half of pregnancy is associated with optimal twin birthweights
Weight gain of < 0.85 pounds per week before 24 weeks associated with IUGR and morbidity.

109. Carmichael- what are women actually doing? (AJPH, 1998)
Cohort: singleton deliveries with good outcomes at UCSF between
Good outcomes = vaginal delivery, term (>37 weeks), live, AGA, no maternal diabetes or hypertension

110. Carmichael Results

111. Carmichael Discussion
More than half the women fell outside of IOM ranges
Higher gains may be associated with higher postpartum weight retention
Monitoring of weight gain is not highly sensitive when used in isolation
Many questions remain about the utility of monitoring weight gain, standards, and counseling.