Vitamin D, cholecalciferol, is a fat-soluble vitamin generally obtained from fortified milk, juices, fish oils and supplements. The most abundant source, however, is the sun – vitamin D is produced in the skin in response to sunlight exposure. Increasing evidence demonstrates highlights that early growth and related factors in utero and during early infancy can significantly influence long-term skeletal development and peak bone mass.

According to researchers, weak bones during infancy and childhood could predispose these individuals to osteoporosis at a later age.

Babies born in winters typically do not benefit from this natural form of vitamin D. Some studies have suggested that for these sun-deprived babies, maternal vitamin D supplementation could be potentially advantageous. As stated by the US Food and Nutrition Board at the Institute of Medicine of the National Academies, vitamin D intake in pregnancy should be 600 international units (IU) daily, or 15 micrograms (µg). Most prenatal vitamins provide 400 IU (10µg) of vitamin D per tablet.

Study: Assessing Role Of Supplementation On Bone Mineral Content

Vitamin D status of mothers has been seen to have an influence on the bone mass of offspring in various observational studies. However, an association between maternal vitamin D repletion during pregnancy and improved offspring bone mass has not been confirmed via randomized controlled trials.

A study published in The Lancet entitled ‘The Maternal Vitamin D Osteoporosis Study’ (MAVIDOS) assessed whether neonates born to mothers who were given vitamin D supplements during pregnancy had a greater whole-body mineral content (BMC) at birth as opposed to mothers who weren’t given any supplementation.

Methodology And Criteria

The study was a multicenter, double-blind, randomized, placebo-controlled trial. This implies that the participants, as well as the researchers did not know who was receiving the actual supplement and who was administered the placebo.

Participants were recruited between Oct 10, 2008 and Feb 11, 2014 from three study sites in the UK, namely Oxford, Sheffield and Southampton. The inclusion criteria was pregnant women older than 18 years, gestation of less than 17 weeks, with a singleton pregnancy and a serum 25-hydroxyvitamin D concentration of 25–100 nmol/L at 10 to 17 weeks’ gestation.

Women, in sets of 10, were randomly assigned to either cholecalciferol 1000 IU/day group (565 women), or a matched placebo group (569 women). Both were to be taken orally, from 14 weeks’ gestation (or as soon as possible before 17 weeks’ gestation) until their delivery.

The primary outcome observed was neonatal whole-body BMC. The latter was to be assessed with two week of the infant’s birth via dual-energy x-ray absorptiometry (DXA) for those infants who had a usable DXA scan. Safety outcomes were also analyzed in all the participants.

The trial was registered with the International Standard Randomized Controlled Trial registry, ISRCTN 82927713, and the European Clinical Trials Database, EudraCT 2007–001716–23.

Findings: Use Of Vitamin D During Pregnancy

Of the infants in the placebo group, 370 (65 percent) had a usable DXA scan and from the cholecalciferol group, 367 (65 percent) had a usable scan for analysis for the primary endpoint. The neonatal whole-body BMC of infants born to mothers given the supplement did not vary significantly from that of infants from the placebo group. Moreover, no significant differences were observed in safety outcomes, other than a greater percentage of women from the placebo group having severe post-partum hemorrhage as opposed to women in the cholecalciferol group. Lastly, no adverse outcomes were believed to be treatment-related.

Present And Future Prospects

The results of the study demonstrate that administering 1000 IU/day cholecalciferol to pregnant women does not increase the whole-body BMC of offspring. It is the first of its kind to test the early origins hypothesis in human participants, hence having the potential to be the basis of public health policies regarding vitamin D supplementation during pregnancy.

However, the findings do show that this amount of supplementation is sufficient to ensure vitamin D repletion among most women, and is a safe dosage. They also support present regimes with regard to vitamin D supplementation during pregnancy. Moreover, the study presents valuable information for pursuing studies investigating the impact of maternal vitamin D status on different childhood outcomes, such as blood pressure, glucose tolerance, cardiovascular function, immunology and cognitive capabilities (IQ).

Follow-up intervention studies are now underway to assess whether behavioral interventions and nutrition education about healthy dietary practices during pregnancy affect the outcome of babies.