Maternal vitamin D status affects bone growth in early childhood--a prospective cohort study

Abstract

In this prospective study, 87 children were followed up from birth to 14 months with data on maternal vitamin D status during the pregnancy. Postnatal vitamin D supplementation improved vitamin D status but only partly eliminated the differences in bone variables induced by maternal vitamin D status during the fetal period.

Introduction: Intrauterine nutritional deficits may have permanent consequences despite improved nutritional status postnatally. We evaluated the role of prenatal and postnatal vitamin D status on bone parameters in early infancy.

Methods: Eighty-seven children were followed from birth to 14 months. Background data were collected with a questionnaire and a 3-day food record. At 14 months bone variables were measured with peripheral computed tomography (pQCT) from the left tibia. Serum 25-OHD and bone turnover markers were determined. Findings were compared with maternal vitamin D status during pregnancy.

Results: The children were divided into two groups based on vitamin D status during pregnancy. Despite discrepant S-25-OHD at baseline (median 36.3 vs. 52.5 nmol/l, p < 0.001), the values at 14 months were similar (63 vs. 66 nmol/l, p = 0.58) in Low D and High D. Serum 25-OHD increased more in Low D (p < 0.001) despite similar total intake of vitamin D (mean 12.3 μg/day). In Low D, tibial bone mineral content (BMC) was lower at birth but BMC gain was greater (multivariate analysis of variance [MANOVA]; p = 0.032) resulting in similar BMC at 14 months in the two groups. In High D, tibial total bone cross-sectional area was higher at baseline; the difference persisted at 14 months (MANOVA; p = 0.068). Bone mineral density (BMD) and ΔBMD were similar in the two groups.

Conclusions: Postnatal vitamin D supplementation improved vitamin D status but only partly eliminated the differences in bone variables induced by maternal vitamin D status during the fetal period. Further attention should be paid to improving vitamin D status during pregnancy.

Fig. 1

Total intake of vitamin D correlated positively with serum 25-OHD in High D (r = 0.505, p < 0.001), but not in Low D (r = 0.219, p = 0.168). Squares indicate High D and circles indicate Low D

Fig. 2

BMC, CSA and BMD in study groups from baseline to 14 months. Increase in BMC from baseline to 14 months differed between the groups (repeated-measures MANOVA; p = 0.023) (a) due to higher baseline BMC in High D. No difference was observed in BMC between the groups at the 14-month visit. TB CSA from baseline to 14 months was significantly higher in High D than in Low D (repeated-measures MANOVA; p = 0.004) (b) due to the higher baseline CSA in High D. At 14 months, CSA remained 14.6 (SEM = 7.8) mm² (MANOVA; p = 0.068) higher in High D. There was no difference between the groups in BMD during the 14 months (c) or in ΔBMD. Low D and High D groups are represented by circles and squares, respectively. Error bars represent SEMs

Fig. 3

Concentrations of BALP and TRACP in study groups from baseline to 14 months. Low D and High D are represented by circles and squares, respectively. Error bars represent SEM. BALP increased from baseline (repeated-measures MANOVA; p < 0.001) (a) while TRACP concentration remained at the same level during the 14 months (b). There were no differences between the study groups