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Weight Gain During Pregnancy: Reexaming the Guidelines
Mean GWG of normal weight women with twin births ranges from 15.5 to 21.8 kg.
GWG for triplets ranges from 20.5 to 23.0 kg at 32-34 weeks and for quadruplets from 20.8 to 31.0 kg at 31-32 weeks.
When stratified by the World Health Organization (WHO) prepregnancy BMI categories, sample sizes from data on twins are insufficient to designate a range for underweight women with pregravid BMI < 18.5 kg/m2.
The extent to which fat mass accretion is critical rather than incidental to pregnancy is not clear, but unrestrained weight gain leads to postpartum weight retention.
Placental size is strongly correlated with fetal growth, averaging approximately 500 g in singleton pregnancies.
Amniotic fluid weight may affect maternal gestational weight gain by as much as 1 kg at term.
Gestational gains in weight, total body water, total body potassium, protein, and FFM, but not FM, are positively correlated with birth weight across all BMI categories.
Poor plasma volume expansion is associated with a poorly growing fetus and poor reproductive performance.
Pregnancy is a condition of systemic inflammation that also influences maternal and fetal nutrient utilization.
During prolonged fasting, i.e., 16-18 hours, pregnant women are more likely to develop elevated measures of blood βHA and acetoacetate. In women with diabetes, plasma FFA and βHA are inversely associated with intellectual development of the offspring at 3-5 years of age. Therefore, caution is warranted regarding periods of prolonged fasting and weight loss during pregnancy and the development of ketonuria.
Research Recommendation 3-1: The committee recommends that the National Institutes of Health and other relevant agencies should provide support to researchers to conduct studies in all classes of obese women, stratified by the severity of obesity, on the determinants and impact of GWG, pattern of weight gain, and its composition on maternal and child outcomes.
Research Recommendation 3-2: The committee recommends that the National Institutes of Health and other relevant agencies should provide support to researchers to conduct studies on the eating behaviors, patterns of dietary intake and physical activity, and metabolic profiles of