Prenatal but not continued postpartum vitamin D supplementation reduces maternal bone resorption as measured by C-terminal telopeptide of type 1 collagen without effects on other biomarkers of bone metabolism

Vitamin D is a key regulator of bone mineral homeostasis and may modulate maternal bone health during pregnancy and postpartum. Using previously-collected data from the Maternal Vitamin D for Infant Growth (MDIG) trial in Dhaka, Bangladesh, we aimed to investigate the effects of prenatal and postpartum vitamin D3 supplementation on circulating biomarkers of bone formation and resorption at delivery and 6 months postpartum. MDIG trial participants were randomized to receive a prenatal;postpartum regimen of placebo or vitamin D3 (IU/week) as either 0;0 (Group A), 4200;0 (B), 16,800;0 (C), 28,000;0 (D) or 28,000;28,000 (E) from 17 to 24 weeks' gestation to 6 months postpartum. As this sub-study was not pre-planned, the study sample included MDIG participants who had data for at least 1 biomarker of interest at delivery or 6 months postpartum, with a corresponding baseline measurement (n = 690; 53 % of 1300 enrolled trial participants). Biomarkers related to bone turnover were measured in maternal venous blood samples collected at enrolment, delivery, and 6 months postpartum: osteoprotegerin (OPG), osteocalcin (OC), receptor activator nuclear factor kappa-B ligand (RANKL), fibroblast growth factor 23 (FGF23), procollagen type 1 N-terminal propeptide, (P1NP) and carboxy terminal telopeptide of type 1 collagen (CTx). Supplementation effects were expressed as percent differences between each vitamin D group and placebo with 95 % confidence intervals (95 % CI). Of 690 participants, 64 % had 25-hydroxyvitamin D concentrations (25OHD) <30 nmol/L and 94 % had 25OHD < 50 nmol/L at trial enrolment. At delivery, mean CTx concentrations were 27 % lower in group E versus placebo (95 % CI: -38, -13; P < 0.001), adjusting for enrolment concentrations. However, at 6 months postpartum, CTx concentrations were not statistically different in group E versus placebo (14 %; 95 % CI: -5.3, 37; P = 0.168), adjusting for delivery CTx concentrations. Effects on other biomarkers at delivery or postpartum were not statistically significant. In conclusion, prenatal high-dose vitamin D supplementation reduced bone resorption during pregnancy, albeit by only one biomarker, and without evidence of a sustained effect in the postpartum period. However, further evidence is needed to substantiate potential maternal bone health benefits of vitamin D in the postpartum period.

Associations between maternal and infant selenium status and child growth in a birth cohort from Dhaka, Bangladesh

Deficiency of essential trace element, Se, has been implicated in adverse birth outcomes and in child linear growth because of its important role in redox biology and associated antioxidant effects. We used data from a randomised controlled trial conducted among a cohort of pregnant and lactating women in Dhaka, Bangladesh to examine associations between Se biomarkers in whole blood (WBSe), serum and selenoprotein P (SEPP1) in maternal delivery and venous cord (VC) blood. Associations between Se biomarkers, birth weight and infant growth outcomes (age-adjusted length, weight, head circumference and weight-for-length z-scores) at birth, 1 and 2 years of age were examined using regression analyses. WB and serum Se were negatively associated with birth weight (adjusted β, 95 % CI, WBSe delivery: −26·6 (–44·3, −8·9); WBSe VC: −19·6 (–33·0, −6·1)); however, delivery SEPP1 levels (adjusted β: −37·5 (–73·0, −2·0)) and VC blood (adjusted β: 82·3 (30·0, 134·7)) showed inconsistent and opposite associations with birth weight. Positive associations for SEPP1 VC suggest preferential transfer from mother to fetus. We found small associations between infant growth and WBSe VC (length-for-age z-score β, 95 % CI, at birth: −0·05 (–0·1, −0·01)); 12 months (β: −0·05 (–0·08, −0·007)). Weight-for-age z-score also showed weak negative associations with delivery WBSe (at birth: −0·07 (–0·1, −0·02); 12 -months: −0·05 (–0·1, −0·005)) and in WBSe VC (at birth: −0·05 (–0·08, −0·02); 12 months: −0·05 (–0·09, −0·004)). Given the fine balance between essential nutritional and toxic properties of Se, it is possible that WB and serum Se may negatively impact growth outcomes, both in utero and postpartum.

The Association Between Maternal and Umbilical Cord Selenium Status and Fetal and Infant Growth in a Birth Cohort in Dhaka, Bangladesh

Objectives

To estimate the associations of maternal and fetal selenium status [whole blood selenium (WBSe), serum selenium (SerumSe) and selenoprotein P (SEPP1)] with infant growth at birth and 12 months.

Methods

This study included a sub-sample from the randomized, placebo-controlled, multi-arm Maternal Vitamin D for Infant Growth trial in Dhaka, Bangladesh (n = 986). Selenium markers were measured in maternal and cord blood at delivery and scaled to one standard deviation for analyses. WBSe and SerumSe were analyzed by inductively coupled plasma dynamic reaction cell mass spectrometry. SEPP1 was analysed by enzyme-linked immunoassay. Growth outcomes of interest were weight-for-gestational age z score (WAZ), low birthweight (LBW, &lt;1500 g) and small for gestational age (SGA) based on measurements within 48 hours of birth, and infant length-for-gestational-age (LAZ), weight-for-length (WFL) and head circumference-for-gestational age (HCAZ) z scores at birth and 12 months. Associations were estimated by multivariable linear and modified Poisson regression models, adjusting for vitamin D and other potential confounders.

Results

Maternal SerumSe and SEPP1 were not associated with any of the growth outcomes at birth or at 12 months. None of the markers were associated with growth outcomes at 12 months. In adjusted models, higher maternal WBSe (1 SD = 18.5 ug/L) was associated with lower WAZ (β = −0.09, 95% CI: −0.168, −0.007) and an increased risk of LBW (RR: 1.20, 95% CI: 1.03, 1.39). Higher cord WBSe (1 SD = 23.2 ug/L) was associated with lower LAZ at birth (β = −0.089, 95% CI: −0.176, −0.001), lower WAZ (β = −0.10, 95% CI: −0.176, −0.023) and a higher risk of SGA (RR: 1.18, 95% CI: 1.07, 1.31). Higher cord SEPP1 (1 SD = 533.6 ng/mL) was associated with higher LAZ at birth (β = 0.098, 95% CI: 0.018, 0.178), higher WAZ (β = 0.086, 95% CI: 0.019, 0.154) and a decreased risk of SGA (RR: 0.87, 95% CI: 0.79, 0.97).

Conclusions

Both maternal and cord WBSe were negatively associated with measures of fetal growth, yet cord SEPP1 had a positive association. There were no associations with infant size at 12 months. These results do not provide evidence of a beneficial effect of higher maternal or fetal selenium status on fetal or infant growth. Yet, observed discrepancies between cord WBSe and SEPP1 require further investigation.

Funding Sources

This study was funded by the Bill and Melinda Gates Foundation.

Effect of Prenatal and Postpartum Vitamin D Supplementation on Circulating Biomarkers of Maternal Bone Metabolism (P24-048-19)

Objectives

To estimate the dose-dependent effect of prenatal and postpartum vitamin D supplementation on circulating concentrations of biomarkers of maternal bone formation (osteoprotegerin [OPG], osteocalcin [OC], procollagen type 1 amino-terminal propeptide [P1NP], and OPG/RANKL ratio), bone resorption (receptor activator nuclear factor kappa-β ligand [RANKL], and carboxyterminal telopeptide of type 1 collagen [CTX]), and general markers of bone metabolism (fibroblast growth factor 23 [FGF23]), in a pregnancy cohort in Dhaka, Bangladesh.

Methods

This study is a sub-study of the Maternal Vitamin D for Infant Growth trial, a randomized controlled trial in which women were enrolled at 17–24 weeks gestation and randomized to one of five weekly oral vitamin D3 supplements or placebo regimens during pregnancy and up to 6 months postpartum: group A (placebo), group B (4200 IU/week), group C (16,800 IU/week), group D (28,000 IU/week), group E (28,000 IU/week during pregnancy and postpartum). Postpartum, all groups other than group E received placebo. Maternal venous blood samples were collected from MDIG participants at enrolment, delivery and 6 months postpartum. Concentrations of FGF23, CTX, and P1NP were determined using ELISAs and OPG, OC, and RANKL concentrations were determined using a Luminex/Millipore magnetic beads kit. For each biomarker (n range, 344 to 606), linear regression was used to compare each treatment group versus the placebo group adjusting for baseline concentrations. For delivery time point analyses, treatment groups D and E (same prenatal vitamin D dose) were combined, while in postpartum analyses the two groups were separated to estimate the postpartum effect.

Results

At delivery and 6 months postpartum, there were no significant differences in OPG, OC, OPG/RANKL, RANKL, and FGF23 concentrations between each treatment group versus the placebo group (Table 1 and Table 2).

Conclusions

Vitamin D supplementation during the 2ndhalf of pregnancy and up to 6 months postpartum had no effect on markers of bone formation or resorption. Analyses for CTX are underway and will also be presented.

Funding Sources

Bill and Melinda Gates Foundation.

Supporting Tables, Images and/or Graphs