Energy Requirements in Pregnancy • Increased Energy costs in pregnancy: • increased maternal metabolic rate • fetal tissues • increase in maternal tissues
RDA for Energy in Pregnancy - 1989 • 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
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
BEE: Basal Energy Expenditure • Increases due to metabolic contribution of uterus and fetus and increased work of heart and lungs. • Variable for individuals
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.
Growth of Maternal and Fetal Tissues • Calculations Based on: • Hytten • IOM weight gain recommendations
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?
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 kg • Mean birth weight was 3.6 kg
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.”
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
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.
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
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)
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.
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
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.
Sociocultural and behavioral influences on weight gain during pregnancy Hicky, CA. Am J Clin Nutr. 2000;71(supple):1364S-70S.
Characteristics of Women Associated with Inadequate Weight Gain • Lower education levels • Unmarried • Aged > 30 years • Smoking • Multiple parity • Unintended pregnancy • Psychosocial characteristics such as attitude toward weight gain, social support, depression, stress, anxiety, and self-efficacy.
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.
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 • 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. • 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