Impact of maternal dietary carbohydrate intake and vitamin D-related genetic risk score on birth length: the Vitamin D Pregnant Mother (VDPM) cohort study

BACKGROUND: Our objectives were to investigate the relationship between maternal vitamin D status and IGF-1 levels in healthy Minangkabau pregnant mothers and their impact on newborn anthropometry outcomes and to examine whether this relationship was modified by dietary intake using a nutrigenetic approach. METHODS: Healthy singleton pregnant mother and infant pairs (n = 183) were recruited. We created three genetic risk scores (GRSs): a six-SNP GRS based on six vitamin D-related single nucleotide polymorphisms (SNPs) involved in the synthesis of vitamin D (vitamin D-GRS), a two-SNP GRS using SNPs in VDR genes (VDR-GRS) and a four-SNP GRS using SNPs from DHCR7, GC, CYP24A1 and CYP2R1 genes (non-VDR GRS). The effect of the GRSs on IGF-1, vitamin D and newborn anthropometry and the interaction between the GRSs and dietary factors were tested using linear regression analysis. RESULTS: The vitamin D- and non-VDR GRSs were significantly associated with lower 25(OH)D concentration (p = 0.005 and p = 0.001, respectively); however, there was no significant association with IGF-1, and newborn anthropometry outcomes. However, there was a significant interaction of VDR-GRS with carbohydrate intake on birth length outcome (P(interaction) = 0.032). Pregnant mothers who had higher carbohydrate intake (405.88 ± 57.16 g/day) and who carried ≥ 2 risk alleles of VDR-GRS gave birth to babies with significantly lower birth lengths compared to babies born to mothers with < 2 risk alleles (p = 0.008). CONCLUSION: This study identified a novel interaction between VDR-GRS and carbohydrate intake on birth length outcome. These findings suggest that reducing the intake of carbohydrates during pregnancy, particularly for those who have a higher genetic susceptibility, might be an effective approach for preventing foetal growth abnormalities. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12884-022-05020-3.