LGA. Despite a limited number of randomized controlled trials, biological plausibility from animal models is strong. Relative risks for GWG and SGA appear to be higher among women with lower prepregnancy BMI.

  1. The evidence for a relationship between GWG and preterm birth, or between GWG and gestational age at birth is weaker than evidence for an association between GWG and fetal growth, and biological plausibility is weak. Most studies show associations between lower GWG and preterm birth among underweight, and to a lesser extent, normal weight women. Higher GWG among all BMI categories may also be associated with preterm birth. Evidence is insufficient on associations with spontaneous vs. induced preterm birth.

  2. A small number of studies show that GWG is directly associated with fat mass in the newborn period. Insufficient evidence is available on associations between GWG and adiposity in infancy.

  3. A small number of relatively large and recent epidemiologic studies show that higher GWG is associated with childhood obesity as measured by BMI. Although biological plausibility is strong, evidence is insufficient to address effect modification by maternal BMI. Only one study has examined blood pressure as an outcome (finding associations in the same direction as BMI), and none has evaluated fat mass or other cardio-metabolic consequences of adiposity.

  4. Lower GWG may be associated with risk of childhood asthma, chiefly through complications of preterm birth, although evidence is limited.

  5. Higher GWG may be associated with ALL, breast cancer, and ADHD, but the evidence is largely indirect and limited in quantity.

  6. Concern exists that metabolic consequences of weight loss during pregnancy may be associated with poorer childhood neurodevelopmental outcomes. Data are limited but raise the possibility that ketonemia among diabetic women could lead to suboptimal neurologic development.

Recommendation for Research

Research Recommendation 6-1: The committee recommends that the National Institutes of Health and other relevant agencies should provide support to researchers to conduct observational and experimental studies to assess the impact of variation in GWG on a range of child outcomes, including duration of gestation and weight and body com-

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