Lecture 2 - 2004 Physiological adaptations to pregnancy Psychology Energy Weight Gain

Physiology of Pregnancy

Systematic Adjustments to Pregnancy Cardiovascular Respiratory Urinary

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.

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.

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) 600-650 650 700 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.

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).

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

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: 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

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

Hormonal Adjustments 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

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.)(

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.

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

Maternal Nutrient Levels

Nitrogen Balance (g/day)

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

Nutrient Transportation Across The Placenta

Factors Affecting Placental Transfer Diffusion distance - diabetes and infection cause edema of the villi Maternal-placental blood flow Blood saturation with gases and nutrients Maternal-placental metabolism of the substance

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

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.

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

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

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

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

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

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

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

DRI for Energy - New

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

DRI for Energy in Pregnancy - 2002

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

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

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.

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?

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

Poppitt et al., cont. Mean maternal prepregnancy weight was 52 kg Mean prepregnancy BMI was 21.2 + 2 Mean birthweight was 3.0 + 0.1 Mean gestational length was 39.4 Mean weight gain was 6.8 kg Mean fat gain was 2.0 kg at 36 weeks

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

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

Prentice and Goldberg. Energy Adaptations in human pregnancy: limits and long-term consequences. Am J Clin Nutr. 2000;71(supple):1226S-32S.

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 11.6 + 4 Mean birth weight was 3.6

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

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

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?

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.”

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

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

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

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

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

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

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

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

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)

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

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

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

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

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

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) 12.5–18 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.

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

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

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)

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

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

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.

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

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

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

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

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. 2000;71(supple):1364S-70S.

Percent of Women Gaining < 7.3 kg

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

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

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

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

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.

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

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.

Multiple Births Optimal range of birthweight: Twins: 2500-2800 g at 36-37 weeks Triplets: 1900-2000 g at 34-36 weeks Maternal weight gain of 40-50 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.

Carmichael- what are women actually doing? (AJPH, 1998) Cohort: 7002 singleton deliveries with good outcomes at UCSF between 1980-1990 Good outcomes = vaginal delivery, term (>37 weeks), live, AGA, no maternal diabetes or hypertension

Carmichael Results

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.