Energy and Weight Gain in Pregnancy

2010

Energy Requirements in Pregnancy

• Increased Energy costs in pregnancy:– increased maternal metabolic rate – fetal tissues– increase in maternal tissues

DRI for Energy in Pregnancy - 2002

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

• BEE = energy consumed while at rest and fasting

• In pregnancy BEE 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

• Calculations Based on:– Hytten– 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?

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

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

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.

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)

*Obesity is defined as prepregnancy weight > 200 lbs

Morbid obesity is defined as prepregnancy weight > 275 lbs

Prepregnancy Obesity* Washington State,1992-2005

11.4

5.3

1.3

0.30

2

4

6

8

10

12

1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005

Perc

ent

Obesity Morbid Obesity

Obesity by Parity and Race/Ethnicity Washington State, 2003-2005

1924

28

9

2924

3539

1316

05

1015202530354045

Hispanic White AfricanAmerican

AmericanIndian

Asian/PI

Perc

ent O

bese

(BM

I> 3

0)

Primiparous Multiparous

Percentage of US Women Who Gained >40 pounds during pregnancy

(MMWR, February 2008)

(source = birth certificates; singleton delivery only)

Percent of Women Gaining <7.3 kg 37-39

weeks 40

weeks

Non-Hispanic Black

15.5 14.0

Hispanic

12.4 11.2

Non-Hispanic White

8.8 8.0

All US 10.4 9.3

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.

Hicky, CA. Am J Clin Nutr. 2000;71(supple):1364S-70S.

• 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

Hicky, CA. Am J Clin Nutr. 2000;71(supple):1364S-70S.

Weight Gain During Pregnancy: Reexamining the Guidelines (IOM, 2009)

• New Guidelines• Conceptual Framework• Composition and Components of Weight Gain• Determinants of Weight Gain• Maternal Consequences of Weight Gain • Child Consequences of Weight Gain• Determining Optimal Weight Gain• Achieving Recommendations

2009 Guidelines for Specific Populations

Women of Short Stature

“unable to identify evidence sufficient to continue to support a modification of GWG guidelines”

Pregnant Adolescents

“unable to identify evidence sufficient to continue to support a modification of GWG guidelines”

Racial or Ethnic Groups

“Recommendations should be generally applicable to the various racial or ethnic subgroups”

Women with Multiple Fetuses

Provisional Guidelines for Twins (at term):–Underweight: insufficient evidence–Normal Weight: 17-25 kg –Overweight : 14-23 kg –Obese: 11-19 kg

Obesity Classes II and III

Insufficient evidence to develop more specific recommendations.

Components of Weight Gain

Patterns of Maternal Fat Accretion

Determinants of Gestational Weight Gain

Determinants: Social & Policy FindingsHealth Services

Evidence for influence is weak; advice missing, inconsistent, erroneous

Community “neighborhood environments can influence GWG by providing access to healthy foods and opportunities for PA”

Family Married women more likely to gain within guidelines; association between partner violence and insufficient GWG; family support associated with good GWG

SES Interactive and confounding effects; food insecurity in obese women associated with high GWG

Determinants: Genetics• Maternal: insufficient evidence• Fetal: GWG associated with birthweight; preliminary

conclusions about fetal genotype and birthweight:(a) there is a fetal genotype effect on weight at birth (about 30

percent of the adjusted variance) (b) both parents’ genes influence birth weight with a stronger effect

for maternal genes (c) specific allelic variants have been associated with weight at

birth (d) mutations in GCK and HNF1β are associated with low birth

weight(e) mutations in HNF4α are associated with high birth weight (f) a few quantitative trait loci on chromosomes 6, 10, and 11 have

been uncovered from genome-wide linkage scans

Determinants: Maternal Factors

Pregravid BMI In general GWG decreases as BMI increases; but large variation

Hyperemesis Gravidarum

Mild n/v no adverse effect; HG lower GWG

Disordered Eating

AN: variableBN: greater GWG

Depression Both low and high GWG

Stress Low GWG

Determinants: Maternal Behaviors

Diet Relationship between energy intake and GWG; insufficient evidence for diet composition and GWG

Physical Activity

Inverse relationship between PA and GWG

Tobacco “Limited” evidence for inverse association with GWG; smoking has independent effect on birth weight.

“There remains a lack of information to relate dietary intake or physical activity to GWG even though they are primary determinants of weigh gain in non-pregnant individuals.”

Consequences of GWG for Mother

• Strong association between high GWG &:– increased risk of cesarean delivery– postpartum weight retention (3 mos to 3 yr)

• Modest association:– failure to initiate breastfeeding

• Inconclusive evidence: – pregnancy complications like glucose intolerance and

gestational hypertensive disorders– long term health consequences

Consequences of GWG for Child

• Studies consistently show linear relationship between GWG and birthweight for gestational age.

• Some, but limited evidence for associations between GWG and:– Still birth– Preterm birth (at both low and high GWG)– Childhood asthma and low GWG– High GWG and some cancers and ADHD– High GWG and childhood obesity

Determining Optimal Weight Gain

• “Evidence is remarkably clear that prepregnant BMI is an independent predictor of many adverse outcomes of pregnancy.”

• Limited data to link GWG to health outcomes of mothers and children after the neonatal period.

Approaches to Achieving Recommendations

Current Situation…

IOM States that full implementation of guidelines would mean:

• Preconceptual services offered to all overweight & obese women to help them reach a healthy weight before conceiving

• Offering services, such as counseling on diet and PA during pregnancy to all pregnant women.

• Offering services to all postpartum women

5 Action Recommendations1. DHHS conduct routine surveillance of GWG and

postpartum weight retention2. All states adopt revised version of birth certificate that

includes maternal pp weight, height, weight at delivery, gestational age at last measured weight (and strive for 100% completion of fields).

3. Fed/state/local agencies and health care providers inform women of importance of conceiving at a normal BMI

4. Agencies/organizations adopt new guidelines and publicize to members and women

5. Providers of prenatal care should offer counseling on dietary intake and PA that is tailored to life circumstances.