The effect of prenatal dietary protein intake on birth weight

From 1940 to 1980, protein deficiency was implicated in depressed fetal gro wth and impaired infant development, Consequently, increasing protein intak e in pregnancy was recommended. In 1980, a randomized controlled trial foun d high protein supplements to be associated with depressed birth weight in low-income pregnant women. The objective of this study was to assess the ro le of dietary protein during pregnancy in women consuming a self-selected d iet. The relation between dietary protein intake and pregnancy outcome was explored in an observational, longitudinal study of low income, mostly urba n women. Protein intake was estimated using the average of two 24-hour diet ary recalls, the first generally completed between months 4 to 6 and the se cond in month 8 of pregnancy. Hierarchical multiple regression analyses wer e conducted, adjusted for maternal, infant and sociodemographic characteris tics and for duration of gestation and maternal energy intake. This study f ound that mean protein intake greater than or equal to 85 g/day was associa ted with a 71 g decrement in birth weight (n = 2163, p = 0.009) compared to intermediate (50-84.9 g/day) average protein intake. About 36% of the wome n studied reported mean intakes of greater than or equal to 85 g protein da ily during pregnancy, whereas only 12% had low protein intakes (<50 g/day). Thus, the negative effect of high protein intake on birth weight may have considerable public health significance and should not be encouraged. (C) 2 001 Elsevier Science Inc. All rights reserved.