Maternal weight gain pattern and birth weight.

OBJECTIVES: To determine the relationship between maternal weight gain pattern and birth weight.
METHODS: All nonobese, white women delivered at the University of California, San Francisco, between 1980-1990 were eligible for this study. Our study group included 2994 uncomplicated pregnancies with complete data. All recorded prenatal weight gain measurements were used to estimate maternal trimester weight gain, pattern of gain (based on low versus not-low gain at each trimester), and total gain at delivery. Multiple linear regression analysis was used to assess the relationship between these weight gain measurements and fetal birth weight.
RESULTS: After adjustment for seven covariates, each kilogram of maternal gain in the first, second, and third trimesters was associated with statistically significant increases in fetal birth weight of 18.0, 32.8, and 17.0 g, respectively. When compared with the pattern of gain that was not low in any trimester, patterns with low gain in the first and second trimesters or in the second and third trimesters were associated with significant decreases in birth weights of 133.0 and 88.5 g, but no important change in birth weight was seen for the group whose gains were low in the first and third trimesters. These findings were not due to differences in total weight gain, which averaged approximately 11 kg in these three pattern groups.
CONCLUSION: The results suggest that specific patterns of maternal weight gain, particularly weight gain during the second trimester, are related to fetal birth weight.