Maternal plasma vitamin D levels across pregnancy are not associated with neonatal birthweight: findings from an Australian cohort study of low-risk pregnant women

Abstract

Background In utero environments can be highly influential in contributing to the development of offspring obesity. Specifically, vitamin D deficiency during pregnancy is associated with adverse maternal and child health outcomes, however its relationship with offspring obesity remains unclear. We assessed maternal vitamin D status across pregnancy, change in plasma vitamin D concentrations and associations with neonatal birthweight, macrosomia and large for gestational age. Methods Women (n = 221) aged 18–40 years with singleton (low-risk) pregnancies, attending antenatal clinics at a tertiary-level maternity hospital were recruited at 10–20 weeks gestation. Medical history, maternal weight and blood samples at three antenatal clinic visits were assessed; early (15 ± 3 weeks), mid (27 ± 2 weeks) and late (36 ± 1 weeks) gestation. Maternal 25(OH)D was analysed from stored plasma samples via liquid chromatography-tandem mass spectrometry (LC/MS/MS). Neonatal growth parameters were collected at birth. Unadjusted and adjusted linear and logistic regression assessed associations of maternal vitamin D with birthweight, macrosomia and large for gestational age. Results Mean plasma 25(OH)D increased from early (83.8 ± 22.6 nmol/L) to mid (96.5 ± 28.9 nmol/L) and late (100.8 ± 30.8 nmol/L) gestation. Overall 98% of women were taking vitamin D-containing supplements throughout their pregnancy. Prevalence of vitamin D deficiency (25(OH)D < 50 nmol/L) was 6.5%, 6.3% and 6.8% at early, mid and late pregnancy respectively. No statistically significant association was found between 25(OH)D or vitamin D deficiency at any timepoint with neonatal birthweight, macrosomia or large for gestational age. Conclusions Prevalence of vitamin D deficiency was low in this cohort of pregnant women and likely related to the high proportion of women taking vitamin D supplements during pregnancy. Maternal 25(OH)D did not impact offspring birth weight or birth size. Future studies in high-risk pregnant populations are needed to further assess maternal vitamin D status and factors in utero which promote early life obesity.

A Study of Vitamin D Status and Its Influencing Factors among Pregnant Women in Szeged, Hungary: A Secondary Outcome of a Case–Control Study

“…Together with other VD supplementation avenues (22.4%), 77.6% of included women took in VD with vitamin complexes. An Australian cohort study of low-risk pregnant women reported much higher supplementation practices: almost all of the included women (97.7%) took some form of VD-containing supplement during pregnancy, with 93.5% prenatal multivitamin usage and 62.6% taking VD together or without pregnancy multivitamins [36]. Low awareness about VD content was also found among Irish women, as 57.9% of those women who reported not taking any VD supplements had actually taken prenatal vitamins including VD [37].…”

Neonatal Vitamin D and Associations with Longitudinal Changes of Eczema up to 25 Years of Age

“…The protective association between neonatal vitamin D and early-onset persistent eczema suggests that vitamin D supplementation during pregnancy might reduce the risk of this outcome. Neonatal vitamin D level is a reflection of maternal vitamin D status, and supplementation during pregnancy increases neonatal vitamin D [18,19]. Current guidelines [24][25][26] do not recommend the routine use of vitamin D supplementation during pregnancy.…”

“…We observed consistent evidence that for every 10 nmol/L increase in neonatal vitamin D, the risk of eczema was reduced by approximately 11%. Maternal vitamin D level during pregnancy is a key driver of neonatal vitamin D [18], and vitamin D supplementation during pregnancy increases the neonatal vitamin D level [19]. Despite this, clinical trials of maternal vitamin D supplementation during pregnancy have not shown consistent protective effects [20][21][22][23], possibly due to lack of power, and/or contamination of the control group.…”