High daily dose of Vitamin D in pregnancy may improve infant outcomes

A previous research has suggested a high prevalence of vitamin D deficiency in pregnant women and their newborn infants.Dr.Sidrah Nausheen from the Aga Khan University in Karachi, Pakistan and colleagues have conducted a Study and found that a high daily dose of vitamin D (4,000 IU/day) resulted in a reduction in vitamin D deficiency in pregnant women, coupled with a lower risk of preterm births and low birth weight in their newborns.The study has been presented at RCOG 2018 in Singapore.

“[Thus], assessment of dose of vitamin D is critical during pregnancy to provide the foetus and neonate with adequate vitamin D stores during development and growth. The current recommended daily intake of 400 IU/day is not sufficient to prevent complications and hypovitaminosis,” said Nausheen.

The researchers conducted a double-blind, hospital-based trial conducted at the Aga Khan University Hospital in Kharadar, Pakistan, researchers randomized 350 women aged 15–45 years (mean age 26.0 years) with singleton pregnancies at <16 weeks gestation to receive vitamin D in doses of 400, 2,000, or 4,000 IU/day (n=115, 115, and 120, respectively), with the 400 IU/day dose serving as the control group. The final number of women assessed was 272.Women with multiple pregnancies and those with pre-existing type I or type II diabetes or hypertension were excluded.

A blood sample was taken at a time of recruitment and assessed for vitamin D, calcium, phosphorus, and alkaline phosphatase levels, while another sample was taken at a time of delivery to assess for vitamin D status.

About 50 percent of the women were determined as acquiring adequate sunlight, with 96.3 percent of women wearing a veil or burqa when outdoors.

Higher doses of vitamin D significantly reduced the incidence of vitamin D deficiency (<20 ng/mL), decreasing from 97.5 percent of women at baseline to 40 percent following 4,000 IU/day, 94.8 percent at baseline to 82 percent following 2,000 IU/day, and 96.4 percent at baseline to 91.2 percent following 400 IU/day. [RCOG 2018, abstract 6914]

Women who received a 4,000 IU/day dose of vitamin D had a lower risk of preterm birth (≤37 weeks gestation) compared with women who received the 400 IU/day dose (5.6 percent vs 17.6 percent, odds ratio [OR] 0.61, 95 percent confidence interval [CI], 0.46–0.82; p=0.05).

Women on 4,000 IU/day also had a lower risk of delivering infants with low birth weight (≤2.5 kg) than those on 400 IU/day (5.6 percent vs 20.9 percent, OR, 0.57, 95 percent CI, 0.44–0.75; p=0.01).

Risk of pre-eclampsia or gestational diabetes did not significantly differ between women on different vitamin D doses (p=0.99 and 0.70, respectively). There was no incidence of stillbirth in this study population.

“Our study findings provide evidence that high dose of vitamin D [4,000 IU/day] has a significant impact on the reduction of vitamin D deficiency among mothers [with] no adverse event reported during the study,” said Nausheen.

“There [was] significant reduction in preterm births and low birth weight babies although no effect on pre-eclampsia [or diabetes] was seen,” she said, calling for larger randomized trials to confirm these findings.