Determinants of changes in vitamin D status postpartum in Swedish women

British Journal of Nutrition
Q1
Nov 2015
Citations:10
Influential Citations:3
Observational Studies (Human)
80
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Enhanced Details

Methods
Prospective cohort study of 78 healthy Swedish women assessed postpartum at 2 weeks, 4 months and 12 months; mean age 32.9 years (SD 3.4). Repeated measures collected lactation status, sun exposure, estrogen contraceptive use, physical activity, dietary vitamin D intake and anthropometrics; serum 25(OH)D measured by LC-MS/MS.
Intervention
Vitamin D supplementation; mean daily intake among users at three postpartum timepoints: 2 weeks postpartum 7.0 ± 8.7 µg/d; 4 months postpartum 5.1 ± 4.5 µg/d; 12 months postpartum 7.3 ± 12.4 µg/d.
Results
Mean serum 25(OH)D did not change between 2 weeks and 12 months postpartum (67 ± 23 vs 67 ± 19 nmol/L). A time effect was observed (P=0.048) with no association between lactation and 25(OH)D changes. Independent determinants of 12-month changes were use of vitamin D supplements (P=0.003), use of estrogen contraceptives (P=0.013), and season (P=0.005). In multivariable analysis, season, baseline 25(OH)D, vitamin D supplement use, and estrogen contraceptive use remained significant and explained about 37% of the variance in 25(OH)D changes. Practical takeaway: postpartum vitamin D status remains largely stable in this cohort, and variation is mainly driven by supplementation, estrogen contraceptive use, and season.
Limitations
Small sample size (n=78) and homogeneous Swedish population; observational design; limited number of estrogen contraceptive users; potential selection bias; results may not generalize to other populations.

Abstract

Abstract Low vitamin D status has been associated with unfavourable health outcomes. Postpartum, it is speculated that maternal vitamin D status decreases due to transfer of vitamin D from mother to child through breast milk. A few studies have inves...