Ethnic differences exist in the associations of 25-hydroxyvitamin D [25(OH)D], parathyroid hormone (PTH) and calcium with important perinatal outcomes, according to a recent study published in the journal, Scientific Reports. Findings suggest a higher average 25(OH)D increases the risk for gestational hypertension in Pakistani women. In White British women, higher calcium concentrations increased the risk for gestational hypertension but reduced the risk for preterm birth.
The Born in Bradford cohort study included 476 White British and 534 Pakistani origin mother-offspring pairs. Maternal pregnancy concentrations of serum 25(OH)D, plasma PTH and serum calcium were evaluated at median 26.3 weeks of gestation. Associations between vitamin D, PTH and calcium with gestational hypertension, pre-eclampsia, caesarean section, preterm birth and small for gestational age were assessed.
Pakistani vs White British women had lower 25(OH)D and higher PTH and similar calcium concentrations. Greater proportion of White British vs Pakistani women developed gestational hypertension, pre-eclampsia and had a caesarean or preterm birth. Delivery of a small for gestational age baby was more common in Pakistani women.
In Pakistani women, higher concentrations of 25(OH)D were associated with 60% increased odds of gestational hypertension (Pinteraction<.01 whereas higher pth levels were associated with relative reduction>interaction=.10). Strong statistical support for the ethnic difference was observed. In White British women, each 1 standard deviation increase in calcium concentration was associated with a 34% increase in developing gestational hypertension but a 33% reduction in the odds of preterm birth. However, there was no strong statistical support for any ethnic differences (Pinteraction≥1.0).
Authors conclude that magnitude or direction of associations between 25(OH)D, PTH and calcium with these outcomes differed between White British and Pakistani women. They call for future research examining these associations together with a range of perinatal outcomes for assessing the risk-benefit action of each.