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Extra vitamin D during pregnancy may increase chance of a 'natural' birth

Women who take extra vitamin D during their pregnancy are more likely to have a 'natural' delivery, according to new research.

'Natural' childbirth, or spontaneous vaginal birth, can be safer for the baby and lead to faster recoveries for the mum. Benefits also include a lower risk of medical interventions.

Southampton researchers led a national study that trialled vitamin supplements in pregnancy. Their analysis found that more of the women given extra vitamin D had a natural delivery.

The research has been published in the Journal of Public Health.

Boosting vitamin D

Researchers from the University of Southampton and University Hospital Southampton NHS Foundation Trust (UHSFT) led the study, called MAVIDOS.

965 women from Southampton, Oxford and Sheffield took part. During their pregnancy, they were randomly allocated to two groups.

One group took an extra 1,000 International Units (IU) per day of vitamin D. The other group took a placebo (dummy) tablet each day. The pregnant women, doctors and midwives did not know which group they were in.

The researchers followed up the women during their pregnancy and delivery, and then compared the two groups.

More of the women in the extra vitamin D group had a natural delivery. This means that they delivered their baby through the birth canal without medical help.

The researchers observed that the number of women in each group needing a caesarean operation to deliver their baby was similar.

Fewer women from the vitamin D group had an assisted delivery, in which a suction cup or forceps are used to help deliver the baby through the birth canal.

Informing public health policy

The Southampton research team are based in the MRC Lifecourse Epidemiology Centre (MRC LEC) and the NIHR Southampton Biomedical Research Centre (BRC). The NIHR Southampton BRC is part of the National Institute for Health and Care Research (NIHR) and hosted by UHSFT in partnership with the University of Southampton.

Dr Rebecca Moon, a Clinical Lecturer and paediatrician in Southampton, led the analysis.

She said: “Most women want to have a natural delivery of their baby. Our work suggests that taking extra vitamin D during their pregnancy might help them to achieve this.

“The women taking the extra vitamin D also had less blood loss after delivery, highlighting why this is so important. Further evidence is now needed to more thoroughly inform public health policy and clinical practice.”

Added benefits of vitamin D

These findings are part of a large project looking at the benefits of vitamin D supplementation in pregnancy.

Professor Nicholas Harvey is an MRC LEC Deputy Director, Professor of Rheumatology and Clinical Epidemiology and project lead.

He said: “Vitamin D deficiency is very common in the UK. We have also shown that extra vitamin D in pregnancy can improve the mother’s vitamin D level and has benefits to their child’s skeleton. Importantly, National Institute for Health and Care Excellence guidance recommends that all pregnant women take 400 IU vitamin D per day.”

Professor Cyrus Cooper, MRC LEC Director, Professor of Rheumatology, and Chief Investigator of the MAVIDOS Trial, added: “These findings add further to the knowledge generated through the MAVIDOS trial. This is informing the role of vitamin D in pregnancy for offspring bone development and underlying genetic and nongenetic mechanisms.

“This successful programme has clearly demonstrated the immense added value through a nationally, collaborative approach to discovery science.”


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