Association of maternal protein intake before conception and throughout pregnancy with birth weight

Background. The aim of this study is to analyze how the maternal intake of macronutrients before conception and in the 6th, 10th, 26th, and 38th weeks of pregnancy affects birth weight. Methods. A longitudinal study of food consumption to assess the nutritional status of 77 healthy female volunteers (age range: 24-36) who were planning immediate pregnancy was performed in Reus between 1992 and 1996. A seven-consecutive-day dietary record was used in order to evaluate the dietary intake. We fitted multiple linear regression models of macronutrients on birth weight adjusted for energy intake, maternal age, pre-conceptional body mass index, sex of the newborn, length of pregnancy, parity, physical activity in leisure time, and smoking. Results. In the 6th, 10th, and 26th weeks of pregnancy, 7.2-12.7% of the variability of the birth weight can be explained by the intake of macronutrients. In the protein and fat model, a 1 g increase in maternal protein intake during preconception and in the 10th, 26th, and 38th weeks of pregnancy leads to a significant increase of 7.8-11.4 g in birth weight. Conclusions. The diet of well-nourished women in the preconception period and throughout most of pregnancy has a significant effect on birth weight, and proteins are the macronutrient that has the greatest influence.