November 15, 2017

Adequate Vitamin D Leads to Higher Live Birth Rate After ART in Women

Among women undergoing assisted reproduction treatment (ART), those with adequate vitamin D levels were a third more likely to deliver a live baby, compared with women whose levels were deficient or insufficient, a recent systematic review and meta-analysis suggests. The researchers are now calling for a randomized clinical trial to study the potential effect of vitamin D supplementation on live birth rates with ART.

Justin Chu, MBChB, MRCOG, PG Cert HP, from Tommy's National Centre for Miscarriage Research, Institute of Metabolism and Systems Research, University of Birmingham, and Birmingham Women's and Children's NHS Foundation Trust, both in the United Kingdom, and colleagues report their findings online recently on 15 November in Human Reproduction.

"Although an association has been identified, the beneficial effect of correction of vitamin D deficiency or insufficiency needs to be tested by performing a clinical trial. In the meantime, women who want to achieve a successful pregnancy should not rush off to their local pharmacy to buy vitamin D supplements until we know more about its effects. It is possible to overdose on vitamin D and this can lead to too much calcium building up in the body, which can weaken bones and damage the heart and kidneys," Dr Chu cautioned in a news release.

The meta-analysis included 11 published studies with 2700 women receiving ART (in vitro fertilization, intracytoplasmic sperm injection, and/or frozen embryo transfer) who had undergone blood testing for vitamin D levels. All studies reported clinical pregnancy as an outcome. The researchers considered vitamin D concentrations of more than 75 nanomoles per litre of blood (nmol/L) to be sufficient, concentrations of less than 75 nmol/L to be insufficient, and less than 50 nmol/L to be deficient.

"One startling finding was the high prevalence of vitamin D deficiency among these women. We found that only 26% of women in the studies had sufficient concentrations of vitamin D; 35% had deficient concentrations and 45% had insufficient concentrations," coauthor, Ioannis Gallos, DMS, MD, MRCOG, academic clinical lecturer and subspecialist trainee in reproductive medicine and surgery, also from Tommy's National Centre for Miscarriage Research, Institute of Metabolism and Systems Research, University of Birmingham, and Birmingham Women's and Children's NHS Foundation Trust, in the United Kingdom, said in the news release.

Seven studies including 2026 patients reported live birth as an outcome. Women with adequate vitamin D levels were more likely to deliver a live infant than those who had deficient or insufficient vitamin D (odds ratio [OR], 1.33; 95% confidence interval [CI], 1.08 - 1.65).

Five studies including 1700 patients determined that women with adequate vitamin D levels had better chances of having a positive pregnancy test (biochemical pregnancy) compared with women whose vitamin D levels were deficient or insufficient (OR, 1.34; 95% CI, 1.04 - 1.73).

Similarly, women with adequate vitamin D levels were more likely to achieve clinical pregnancy (the presence of fetal heart approximately 5 weeks after embryo transfer; OR, 1.46; 95% CI, 1.05 - 2.02).

However, vitamin D did not appear to be related to miscarriage in the six studies including 1635 patients that examined the endpoint (OR, 1.12; 95% CI, 0.81 - 1.54).

The researchers say the improved ART success in women replete in vitamin D "could be via the actions of vitamin D on the endometrium promoting embryo implantation or as a surrogate marker for general well-being."

As vitamin D testing and treatment of deficiency are relatively inexpensive, "it may be beneficial to diagnose and treat vitamin D deficiency in women planning ART to optimize their pregnancy outcomes," the researchers write. "Correction of vitamin D deficiency in these patients would also be of benefit during pregnancy, as replete vitamin D concentrations have been found to reduce the risk of obstetric complications such as gestational diabetes, pre-eclampsia, and fetal growth restriction."
The authors have disclosed no relevant financial relationships.

1). Justin C, Ioannis G, Aurelio T, et al. Vitamin D and assisted reproductive treatment outcome: a systematic review and meta-analysis. Human Reproduction. Published online November 15, 2017. Full text here:

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