A new study finds a link between the use of fertility treatments and a substantial increase in the rate of multiple births in the United States, but a decline in the number of triplets and other high-order births when using in vitro fertilization or IVF.
"The good news is that we made progress in those that are triplets and above from IVF and the bad news is we haven't done as well with twins," said Dr. Tommaso Falcone, who did not take part in the study but treats IVF patients at Cleveland Clinic.
Researchers at the Centers for Disease Control observed the rates of twin births and of triplet and high-order births from 1971 through 2011. They found twin birth rates significantly increased during that time and tied the increase to the use of non-IVF practices, or the use of fertility drugs, which have more unpredictable outcomes.
Researchers say an increased awareness of multiple births resulting from non-IVF fertility treatments may lead to improved practices and a decrease in the twin birth rate.
Falcone expects the number of triplets, and high-order-multiple births conceived through ivf to continue to drop. He credits advances in the field, particularly the more common practice of transfering only one embryo at a time. But he says non-IVF treatments will remain hard to predict.
"For non-IVF fertility it's unclear because non-IVF fertility is again, not creating an embryo, so therefore it's created inside the woman and that may have less control of the number of eggs released and so-on," said Falcone.
Complete findings for this study are in the New England Journal of Medicine.