Maternal plasma n-3 and n-6 polyunsaturated fatty acids during pregnancy and features of fetal health: Fetal growth velocity, birth weight and duration of pregnancy.

BACKGROUND & AIMS: Maternal fatty acids are essential for fetal growth and development. Here, we examine associations between maternal mid-pregnancy plasma n-3 and n-6 polyunsaturated fatty acids (PUFAs) and fetal health determined by fetal growth velocity, birth weight and duration of pregnancy. METHODS: Participants were 6974 pregnant women and their infants from a population-based birth cohort, the Generation R Study. Maternal plasma n-3:n-6 PUFA ratio and n-3 and n-6 PUFA percentage in glycerophospholipids in mid-pregnancy were related to fetal growth velocity calculated from repeatedly measured weight, length and head circumference, birth weight, and duration of pregnancy. RESULTS: A higher maternal mid-pregnancy n-3:n-6 PUFA ratio was associated with a higher growth velocity of the fetal weight (ß = 0.082 SD-score/week, 95% CI 0.055; 0.108, P < 0.001), length (ß = 0.085 SD-score/week, 95% CI 0.052; 0.119, P < 0.001); and head (ß = 0.055 SD-score/week, 95% CI 0.019; 0.091, P = 0.003). We also observed positive associations between n-3:n-6 PUFA ratio and birth weight (ß = 0.76 SD-score, 95% CI 0.22; 1.29, P = 0.006), and duration of pregnancy (ß = 1.32 weeks, 95% CI 0.24; 2.40, P = 0.02). CONCLUSIONS: These results are consistent with the hypothesis that a higher n-3:n-6 PUFA ratio is important for fetal health.

Determinants of maternal pregnancy one-carbon metabolism and newborn human DNA methylation profiles.

Maternal one-carbon (1-C) metabolism provides methylgroups for fetal development and programing by DNA methylation as one of the underlying epigenetic mechanisms. We aimed to investigate maternal 1-C biomarkers, folic acid supplement use, and MTHFR C677T genotype as determinants of 1-C metabolism in early pregnancy in association with newborn DNA methylation levels of fetal growth and neurodevelopment candidate genes. The participants were 463 mother-child pairs of Dutch national origin from a large population-based birth cohort in Rotterdam, The Netherlands. In early pregnancy (median 13.0 weeks, 90% range 10.4-17.1), we assessed the maternal folate and homocysteine blood concentrations, folic acid supplement use, and the MTHFR C677T genotype in mothers and newborns. In newborns, DNA methylation was measured in umbilical cord blood white blood cells at 11 regions of the seven genes: NR3C1, DRD4, 5-HTT, IGF2DMR, H19, KCNQ1OT1, and MTHFR. The associations between the 1-C determinants and DNA methylation were examined using linear mixed models. An association was observed between maternal folate deficiency and lower newborn DNA methylation, which attenuated after adjustment for potential confounders. The maternal MTHFR TT genotype was significantly associated with lower DNA methylation. However, maternal homocysteine and folate concentrations, folic acid supplement use, and the MTHFR genotype in the newborn were not associated with newborn DNA methylation. The maternal MTHFR C677T genotype, as a determinant of folate status and 1-C metabolism, is associated with variations in the epigenome of a selection of genes in newborns. Research on the implications of these variations in methylation on gene expression and health is recommended.

Epigenetic profiles in children with a neural tube defect; a case-control study in two populations.

Folate deficiency is implicated in the causation of neural tube defects (NTDs). The preventive effect of periconceptional folic acid supplement use is partially explained by the treatment of a deranged folate-dependent one carbon metabolism, which provides methyl groups for DNA-methylation as an epigenetic mechanism. Here, we hypothesize that variations in DNA-methylation of genes implicated in the development of NTDs and embryonic growth are part of the underlying mechanism. In 48 children with a neural tube defect and 62 controls from a Dutch case-control study and 34 children with a neural tube defect and 78 controls from a Texan case-control study, we measured the DNA-methylation levels of imprinted candidate genes (IGF2-DMR, H19, KCNQ1OT1) and non-imprinted genes (the LEKR/CCNL gene region associated with birth weight, and MTHFR and VANGL1 associated with NTD). We used the MassARRAY EpiTYPER assay from Sequenom for the assessment of DNA-methylation. Linear mixed model analysis was used to estimate associations between DNA-methylation levels of the genes and a neural tube defect. In the Dutch study group, but not in the Texan study group we found a significant association between the risk of having an NTD and DNA methylation levels of MTHFR (absolute decrease in methylation of -0.33% in cases, P-value = 0.001), and LEKR/CCNL (absolute increase in methylation: 1.36% in cases, P-value = 0.048), and a borderline significant association for VANGL (absolute increase in methylation: 0.17% in cases, P-value = 0.063). Only the association between MTHFR and NTD-risk remained significant after multiple testing correction. The associations in the Dutch study were not replicated in the Texan study. We conclude that the associations between NTDs and the methylation of the MTHFR gene, and maybe VANGL and LEKKR/CNNL, are in line with previous studies showing polymorphisms in the same genes in association with NTDs and embryonic development, respectively.