Determinants of Postpartum Vitamin D Status in the Caucasian Mother-Offspring Pairs at a Latitude of 52°N: A Cross-Sectional Study

BACKGROUND

High prevalence of vitamin D deficiency in pregnancy is recorded.

AIM

To establish determinants of postpartum 25-hydroxyvitamin D (25(OH)D) levels on mothers and offspring.

METHODS

25(OH)D level was measured in cord blood and maternal blood collected ≤3 weeks postpartum. Maternal socioeconomic status, vitamin D intake, sun exposure during pregnancy and maternal and neonatal fat mass (FM; dual X-ray absorptiometry) were assessed within 3 weeks postpartum.

RESULTS

A total of 174 mother-offspring pairs were enrolled. Maternal 25(OH)D <20 ng/ml was seen in 32 (51%) of summer and 82 (74%) of winter deliveries. Women with 25(OH)D <20 ng/ml had a 2-fold lower percentage of vitamin D intake of ≥800 IU/day than women with 25(OH)D ≥20 ng/ml (p = 0.02). FM (%) was comparable between groups (p > 0.05). Multiple regression analysis revealed the delivery season, prenatal vitamin D intake ≥800 IU/day and duration of supplementation to be the determinants of maternal 25(OH)D level (R(2) = 0.26, p < 0.001). Maternal 25(OH)D level, season of birth and duration of maternal supplementation explained 83% of the variance in cord blood 25(OH)D level (R(2) = 0.83, p < 0.001).

CONCLUSIONS

The key determinants of higher maternal vitamin D status were the summer-autumn season of delivery and prenatal use of ≥800 IU/day of vitamin D. The cord blood 25(OH)D level was mainly determined by maternal 25(OH)D level and season of birth.

Impact of vitamin D supplementation during lactation on vitamin D status and body composition of mother-infant pairs: a MAVID randomized controlled trial

OBJECTIVE

The optimal vitamin D intake for nursing women is controversial. Deterioration, at least in bone mass, is reported during lactation. This study evaluated whether vitamin D supplementation during lactation enhances the maternal and infant's vitamin D status, bone mass and body composition.

DESIGN AND METHODS

After term delivery, 174 healthy mothers were randomized to receive 1200 IU/d (800 IU/d+400 IU/d from multivitamins) or 400 IU/d (placebo+400 IU/d from multivitamins) of cholecalciferol for 6 months while breastfeeding. All infants received 400 IU/d of cholecalciferol. Serum 25-hydroxyvitamin D [25(OH)D], iPTH, calcium, urinary calcium, and densitometry were performed in mother-offspring pairs after delivery, and at 3 and 6 months later.

RESULTS

A total of 137 (79%) (n = 70; 1200 IU/d, n = 67; 400 IU/d) completed the study. 25(OH)D was similar in both groups at baseline (13.7 ng/ml vs. 16.1 ng/ml; P = 0.09) and at 3 months (25.7 ng/ml vs. 24.5 ng/ml; P = 0.09), but appeared higher in the 1200 IU/d group at 6 months of supplementation (25.6 ng/ml vs. 23.1 ng/ml; P = 0.009). The prevalence of 25(OH)D <20 ng/ml was comparable between groups at baseline (71% vs. 64%, P = 0.36) but lower in the 1200 IU/d group after 3 months (9% vs. 25%, P = 0.009) and 6 months (14% vs. 30%, P = 0.03). Maternal and infants' iPTH, calciuria, bone mass and body composition as well as infants' 25(OH)D levels were not significantly different between groups during the study. Significant negative correlations were noted between maternal 25(OH)D and fat mass (R =  -0.49, P = 0.00001), android fat mass (R = -0.53, P = 0.00001), and gynoid fat mass (R = -0.43, P = 0.00001) after 6 months of supplementation.

CONCLUSIONS

Vitamin D supplementation at a dose of 400 IU/d was not sufficient to maintain 25(OH)D >20 ng/ml in nursing women, while 1200 IU/d appeared more effective, but had no effect on breastfed offspring vitamin D status, or changes in the bone mass and the body composition observed in both during breastfeeding.

TRIAL REGISTRATION

ClinicalTrials.gov NCT01506557.