FRIDAY, May 5 (HealthDay News) -- High levels of folate are associated with an increased likelihood of a twin birth after in vitro fertilization (IVF) with multiple embryo transfer, suggesting that fortifying foods with folic acid could lead to an increase in twin births after fertility treatment, according to a report in the May 6 issue of The Lancet.
Paul Haggarty, Ph.D., from Aberdeen University in the United Kingdom, and colleagues studied 602 women undergoing fertility treatment and assessed their intake of folate and vitamin B12 through a questionnaire and a blood test. The researchers also examined variations in five B-vitamin-related genes in the infertile women and in 932 women who conceived naturally.
The researchers found that although levels of folate and vitamin B12 did not affect the likelihood of a successful pregnancy, women with higher levels of plasma and red-cell folate were significantly more likely to have twins after IVF (odds ratio 1.52 and 1.28, respectively). Women homozygous for the 1298 CC variant rather than the AA variant of the methylenetetrahydrofolate reductase gene were less likely to have a live birth following IVF (OR 0.24) or to have had a previous pregnancy (OR 0.42).
"In women likely to have a successful IVF pregnancy, high folate status increases the likelihood of twin birth after multiple embryo transfer," Haggarty and colleagues conclude. "Proposals to fortify the U.K. diet with folic acid could lead to an increase in the number of twins born after IVF."
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