Influence of Protein Intake on Maternal Weight Gain and Infant Birth Weight Across Pregnancy

Abstract

Protein and amino acid intake during pregnancy appears to influence gestational weight gain (GWG). Nutrient intake and GWG have been linked to birth weight, respectively, with little evidence of the temporal effects. The purpose of this study was to examine maternal protein and amino acid intake on gestational weight gain (GWG) and birth outcomes across pregnancy. Prospectively, we collected dietary intake data from nulliparous women (n=52) during each trimester. We correlated maternal protein and amino acid intake with the defined pregnancy outcomes. We analyzed group differences for total GWG (≤19 lbs. [n=17], ≥25 lbs. [n=18]), 1st to 2nd trimester GWG (≤7 lbs. [n=16], ≥12 lbs. [n=18]), 2nd to 3rd trimester GWG (≤10 lbs. [n=17], ≥16 lbs. [n=18]) and infant birth weight (≤3000g [n=15], ≥3500g [n=21]). Significance was determined at (p<0.05). Among the amino acids (18), there was a marginal correlation between second trimester cystine intake and infant birth weight (p=0.06), as well as group differences (p=0.06). There was no correlation between maternal dietary protein intake and GWG across pregnancy. There were no group differences in protein or amino acid intake for total weight gain, weight gain by trimester or infant birth weight. Maternal dietary protein intake exceeded the recommended 71 g/day for pregnancy limiting ability to determine impact on birth outcomes. Future studies examining variable cysteine intake in pregnancy may identify influence on infant birth weight during critical periods of development.