Weight Gain in Pregnancy Past, Present, and Future

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Weight Gain in PregnancyPast, Present, and Future

• Naomi E. Stotland, MD
• Dept. of Obstetrics, Gynecology, and Reproductive
  Sciences, UCSF

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Weight Gain in Pregnancy - Physiology

• 27.5 lbs (12.5 kg) is normal physiologic gain
  (Hytten 1991)
• 9 kg (20 lbs) is made up of fetus, placenta,
  amniotic fluid, uterine/breast hypertrophy,
  increased blood volume and retained fluid
• 3.5 kg (7.5 lbs) is maternal storage fat

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Pregnancy Weight Gain Recommendations in the U.S.
- History

• 19th century - restriction of food intake to
  prevent difficult labor
• 1901 - first published study of diet and birth
  weight restricted food intake linked to lower
  BW
• 1920s more studies associating weight gain and
  BW

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Pregnancy Weight Gain Recommendations in the U.S.
- History

• 1930s Excessive weight gain seen as sign of
  edema and impending toxemia (preeclampsia)
• Limiting weight gain seen as a way of preventing
  preeclampsia
• Women told to gain 6.8kg (15 lbs)
• Studies from this era report average weight gains
  of lt 20 lbs
• Restricted gain for preservation of figure

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Pregnancy Weight Gain Recommendations in the U.S.
- History

• 1971 Hytten and Leitch published review of
  studies from 1950s and 60s
• Average gain of 12.5 kg (27.5 lbs) is
  physiologic normality in healthy young
  primigravid women
• Association between pre-pregnancy weight, weight
  gain, and birth weight noted in literature
• 1970 National Academy of Sciences Food and
  Nutrition Boards Committee on Maternal
  Nutrition 20-25 lbs recommended
• Associated with low weight gain
• Infant mortality
• Disability
• Mental retardation

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Pregnancy Weight Gain Recommendations in the U.S.
- History

• 1972 ACOG also endorsed the 20-25 lb guideline
• 1981 FNBs Nutrition Services in Perinatal
  Care Inadequate gain 1kg or less/month in 2nd
  and 3rd trimesters, Excessive gain 3kg or
  more/month
• OB textbooks between 1961-1980 had differing
  recommendations on weight gain

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Pregnancy Weight Gain Recommendations in the U.S.
- History

• Recommended gains have nearly doubled from the
  1930s until the present
• In past, food intake was restricted, now
  unlimited food intake

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Pregnancy Weight Gain in the U.S. - History

• Are women gaining more than in the past?
• In restrictive era (1930s) women were gaining
  less
• Average weight gain has not changed much over the
  past 20 years, but,
• Percentage of women gaining excessive amounts has
  increased
• Percentage of women who enter pregnancy
  overweight or obese has increased

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Pregnancy Weight Gain in U.S. - Trends

• From 1989 to 2001 (latest data available)
• Percent gaining below 16 lbs has increased by
  about 30 (from 9.4 to 12.1)
• Percent gaining above 40 lbs has increased by
  about 30
• Actual percentage gaining above IOM guidelines
  would be much higher

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What outcomes have been associated with pregnancy
weight gain?

• Birth weight
• SGA/IUGR
• LGA/macrosomia gtgtmaternal morbidities
• Mode of delivery
• Preterm birth
• Postpartum weight retention

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Weight Gain and Birth Weight

• Well-established relationship, even when using
  net weight gain (total weight gain minus birth
  weight of infant)
• Relationship seems to be modified by
  pre-pregnancy body mass index
• Controversy about relationship between weight
  gain and birth weight among obese women

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The IOM Report and Guidelines
IOM Recommendations for Weight Gain in
Pregnancy (1990)
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The IOM Report and Guidelines

• Retrospective, observational data
• First widely-accepted guidelines, BMI-specific
• Controversy over guidelines too high, too low.
• 30 40 of all women
• To date The range for best outcome of the infant

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Weight gain recommendations in Europe Asia

• Austria Max. 15 kg weight gain
• Denmark IOM guidelines
• Finland 15 kg for normal weight women
• Germany No official guidelines
• Switzerland No official guidelines
• UK Not weighing during pregnancy
• Hong Kong BMI specific weight gain
  recommendations
• No information available France, Italy, Spain,
  Sweden

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Weight Gain and Macrosomia

• Strongly associated
• Most cases of macrosomia occur in non-diabetic
  women
• Macrosomia is associated not just with infant
  trauma, but with multiple increased risks of
  maternal morbidity cesarean birth, severe
  perineal lacerations, peripartum infection, and
  prolonged hospital stay (even among those
  delivering vaginally)

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Weight Gain and Cesarean Birth

• High weight gain is associated with increased
  risk of both prolonged labor and cesarean birth
• This relationship is only partly attributable to
  higher birth weight
• Even when birth weight controlled for in
  multivariate analysis, high weight gain is an
  independent risk factor for cesarean birth

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Weight Gain and Preterm Birth

• Multiple epidemiologic studies have associated
  poor gestational gain with increased risk of
  preterm birth
• Obvious confounder of length of gestation as well
  as birth weight most studies have addressed
  this
• Most studies have not stratified by pre-pregnancy
  BMI, some excluded obese women

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Naomi E. Stotland, MD Aaron B. Caughey, MD, MPP,
MPH Barbara Abrams, DrPH.Pre-pregnancy Body
Mass Index, Gestational Weight Gain, and Risk of
Spontaneous Preterm Birth

• Objective To examine how pre-pregnancy BMI
  modifies the effect of gestational weight gain on
  the rate of spontaneous preterm birth.
• Methods Retrospective cohort study at UCSF,
  1976-2001. Total weight gain was divided by
  weeks gestation, approximating a rate of gain.
  Univariate and multivariate analyses.

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Weight Gain and Preterm Birth Study - Results

• Low BMI group gaining below guidelines had PTB
  rate of 5.9 vs. 3.5 for those gaining within
  guidelines (Plt 0.001)
• High BMI group gaining below guidelines had PTB
  rate of 8.1 vs. 3.8 for those gaining within
  guidelines (Plt0.001).
• Normal BMI group gaining below guidelines had PTB
  rate of 5.2 vs. 3.4 for those gaining within
  guidelines (Plt0.001).

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Gestational Weight Gain Methodologic Challenges

• What measure of weight gain to use?
• How reliable are self-reported weights?
• Gestational age assessment
• Race/ethnicity variation
• Limitation of retrospective/epidemiologic data
• Optimal weight gain depends on the outcome one
  studies

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What can we do? Do interventions work?

• Historically guidelines/provider advice can
  impact actual weight gain
• Few studies have linked interventions to outcomes
  beyond kg gained

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Interventions

• By-mail patient education
• Regular clinical meetings for education with
  goal-setting
• Phone calls between visits
• Newsletters
• Personal graph of weight gain

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RCT

• To prevent excessive weight gain in pregnant
  women
• 120 low-income women
• Stepped-care behavioral intervention with usual
  care
• Normal BMI Significant decrease in excessive
  weight gain after intervention
• Overweight BMI Significant increase in excessive
  weight gain after intervention

Polley BA et al. 2002
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Non-randomized (historical) intervention

• To prevent excessive gestational weight gain
• 179 cases, 381 controls (historical), low-income
• Weight gain monitoring and by-mail education
• Reduced risk for excessive weight gain in all BMI
  groups

Olson CM et al. 2004
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Provider and patient knowledge/attitudes

• Body Mass Index, Provider Advice, and Target
  Gestational Weight Gain
• Naomi E. Stotland, MD, Jennifer S. Haas, MD,
  MSPH, Phyllis Brawarsky, MPH, Rebecca A. Jackson,
  MD , Elena Fuentes-Afflick, MD, MPH, and Gabriel
  J. Escobar, MD
• Obstetrics Gynecology 2005105633-638

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Target Weight Gain Study Results

• Among overweight women (prepregnancy BMI
  26.129.0), 24.1 reported a target weight gain
  above the Institute of Medicine (IOM) guidelines,
  compared with 4.3 of normal weight women (P lt
  .001). Among women with a low prepregnancy BMI (lt
  19.8), 51.2 reported a target weight gain below
  the guidelines, compared with 10.4 of normal
  weight women (P lt .001).
• 33 of the cohort reported receiving no provider
  advice about gestational weight gain.
• Latina ethnicity, lower maternal education, low
  prepregnancy BMI (lt 19.8), lack of provider
  advice about weight gain, and provider advice to
  gain below guidelines were all independently
  associated with a target weight gain below IOM
  guidelines.
• Prepregnancy BMI more than 26, multiparity, lower
  age, and provider advice to gain above guidelines
  were all associated with a target gain above IOM
  guidelines.

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Target Weight Gain study Conclusions

• Many women report incorrect target weight gains
  and incorrect or absent provider advice on weight
  gain
• High or low prepregnancy BMI (patients at most
  risk) is a predictor of incorrect target weight
  gain
• Both patients and providers need increased
  familiarity with the IOMs BMI-specific guidelines

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Goals for Future Research

• Studies in overweight/obese women
• Qualitative research patient and provider
  attitudes, beliefs
• RCTs of novel interventions both weight gain
  and other outcomes low glycemic load diet trial
  Janet King PI

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Acknowledgements

• Special thanks to Barbara Abrams, DrPH
• Aaron Caughey, MD, MPH, MPP
• Gabriel Escobar, MD