A Longitudinal Study of 25-Hydroxy Vitamin D and Parathyroid Hormone Status throughout Pregnancy and Exclusive Lactation in New Zealand Mothers and Their Infants at 45° S.

Barry Taylor,Lisa Houghton,Michel De Lange,Adel Mekhail,Shirley Jones,Benjamin Wheeler,Michelle Harper

doi:10.3390/nu10010086

Barry Taylor, Lisa Houghton + Show 5 more

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https://doi.org/10.3390/nu10010086

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Journal: Nutrients	Publication Date: Jan 13, 2018
Citations: 33	License type: CC BY 4.0

Affiliation: University of Otago, Southern District Health Board

Abstract

Vitamin D status and associated metabolism during pregnancy and lactation have been assessed in only a limited number of longitudinal studies, all from the northern hemisphere, with no infant data concurrently reported. Therefore, we aimed to describe longitudinal maternal and infant 25-hydroxy vitamin D (25OHD) and parathyroid hormone (PTH) status during pregnancy and up to 5 months postnatal age, in New Zealand women and their infants living at 45° S latitude. Between September 2011 and June 2013, 126 pregnant women intending to exclusively breastfeed for at least 20 weeks were recruited. Longitudinal data were collected at three time-points spanning pregnancy, and following birth and at 20 weeks postpartum. Vitamin D deficiency (25OHD < 50 nmol/L) was common, found at one or more time-points in 65% and 76% of mothers and their infants, respectively. Mean cord 25OHD was 41 nmol/L, and three infants exhibited secondary hyperparathyroidism by postnatal week 20. Maternal late pregnancy 25OHD (gestation 32–38 weeks) was closely correlated with infant cord 25OHD, r2 = 0.87 (95% CI (Confidence interval) 0.8–0.91), while no correlation was seen between early pregnancy (<20 weeks gestation) maternal and cord 25OHD, r2 = 0.06 (95% CI −0.16–0.28). Among other variables, pregnancy 25OHD status, and therefore infant status at birth, were influenced by season of conception. In conclusion, vitamin D deficiency in women and their infants is very common during pregnancy and lactation in New Zealand at 45° S. These data raise questions regarding the applicability of current pregnancy and lactation policy at this latitude, particularly recommendations relating to first trimester maternal vitamin D screening and targeted supplementation for those “at risk”.

Highlights

Pregnancy is a unique and demanding life stage in terms of vitamin D and calcium metabolism, due to the increased need for fetal development of mineralised structures, while maintaining optimal maternal status
These impacts of low maternal vitamin D status on foetal bone have been reported as early as weeks gestation using high resolution 3D ultrasound showing a poorer fetal fermoral development [16], as well as longer-term follow up studies demonstrating lower peak offspring bone mass at years of age [17]
Infant cord 25OHD status was most strongly correlated with maternal status towards the end of the third trimester, and importantly had no correlation with maternal status prior to 20 weeks gestation

Summary

Introduction

Pregnancy is a unique and demanding life stage in terms of vitamin D and calcium metabolism, due to the increased need for fetal development of mineralised structures, while maintaining optimal maternal status. Other aspects of foetal and child bone health may be impacted by maternal vitamin D status, including foetal growth [4], foetal bone accrual and subsequent bone size [12,13], and dental health including enamel hypoplasia [14] and dental caries [15] These impacts of low maternal vitamin D status on foetal bone have been reported as early as weeks gestation using high resolution 3D ultrasound showing a poorer fetal fermoral development [16], as well as longer-term follow up studies demonstrating lower peak offspring bone mass at years of age [17]

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