The association of maternal diet and dietary supplement intake in pregnant New Zealand women with infant birthweight

Abstract

To investigate the association of infant birthweight with maternal diet and supplement intake. 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. 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). 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.