Gestational weight gain represents a balance between nutrient intake and energy expenditure. Supplementation programs seem to be most effective in poorly nourished women; however, research should focus on what groups may most benefit from supplementation programs or a reduction in physical activity. The epidemiological evidence is very strong that fetal growth increases with increasing gestational weight gain.

Physical activity, particularly heavy work, appears to exacerbate the adverse effects of poor nutritional status on lactation. the subcommittee knows of no information on how various physiological adjustments to physical activity influence lactation performance. It is recommended that studies should be undertaken to examine the effects on lactation as measured by milk volume, composition, feeding frequencies, and infant growth.

Since there are so few data available addressing women's postpartum health and nutrition, the conclusions of the subcommittee are based almost exclusively on complications and immediate outcomes of pregnancy. The subcommittee recommends that future studies include outcome variables related to women together with those related to infants.

Additional studies should also be carried out to explore the possible association between malnutrition and physical activity during pregnancy with complications of delivery. These complications may include the outcome of Caesarean section, maternal mortality, and congenital anomalies.

Implementation of health care services geared toward women's health, including prepregnancy and pregnancy nutritional status and health care, would also be helpful. These services should be able to monitor women who have had complicated pregnancies and deliveries, particularly those who have previously given birth to low-birthweight infants. These services should also support breastfeeding, while considering both the infant's growth and the mother's nutritional status. Current evidence suggests that programs to reduce physical activity would also be most effective in this group; however, more research needs to be done in this area. Many other of the most obviously needed measures fall outside the realm of this report. Some of these are increased access to education (both formal and informal), support for child care (especially for women who are heads of households), improved opportunities for employment, access to technology that saves time and heavy physical activity, and more legislation to protect pregnant women from strenuous physical activity.

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