Objective: To investigate the association of infant birthweight with maternal diet and supplement intake.
Subjects/methods: Prospective cohort study of 504 European and Polynesian urban and rural pregnant volunteers recruited from northern New Zealand clinics. Subjects were visited in months 4 (mth4) and 7 (mth7) of pregnancy when height, weight and skinfolds were measured, questionnaires to determine personal details administered, and diet assessed by a 24-hour recall and 3-day food record.
Results: After adjusting for confounders nutrients accounted for up to 5.0% of the total variance in birthweight. Ethnicity was not a significant confounder. A quadratic relationship existed between birthweight and % total energy (%TE) from carbohydrate, fat and protein, most significantly with carbohydrate energy (P=0.002). Birthweight was greatest (approximately 3600 g) when carbohydrate %TE was 48%, fat 35% and protein 17%. Birthweight was reduced with high beta-carotene intakes (mth4, P=0.009) and with both high retinol and beta-carotene intakes in mth4 and 7 (average). Birthweight was positively associated with increasing pantothenic acid/biotin ratios (P=0.011), magnesium (P=0.000) and vitamin D (P=0.015) intakes in mth4; with biotin (P=0.040) and B(12) intakes above the RDI (P=0.006) in mth7; and with pantothenic acid intake in mth4&7 (P=0.002). Dietary supplement usage was associated with increased birthweight, most significantly iron supplementation (P=0.006).
Conclusion: Birthweight was associated with the %TE from carbohydrate, fat and protein, and with beta-carotene, retinol, vitamins D and B(12), pantothenic acid, biotin and magnesium intakes and iron supplementation. More research may be required on some dietary recommendations for pregnancy.