In vitro fertilization (IVF) is a type of assisted reproductive technology that has gained popularity in the U.S. over the last 20 years. But a new study questions the current recommendations for women who want to try the procedure.
IVF consists of combining a sperm and an egg in a lab dish and then inserting the resulting embryo into the uterus. In order to increase the odds of successful implantation, usually more than one embryo is transferred at a time. According to the 2009 guidelines set by the American Society for Reproductive Medicine, the limit for women between the ages of 35 and 37 is two transfer embryos; for those 38 to 40 years old it is three; and for women 40 to 42, five embryos are the recommended maximum.
However, after analyzing data from more than 124,000 IVF cycles that resulted in over 35,000 births, British researchers found that using more than two embryos doesn t increase the odds of a successful birth; moreover, it may actually raise the risk of complications (especially for women under 40), such as multiple births and low birth weights.
Furthermore, the study found that birth rates for women under the age of 40 were actually lower when three embryos were used instead of two. And in women over 40, there was no significant difference in birth rates whether two or three embryos were used.
IVF involving three or more embryos occurs about 40 percent of the time in the U.S., but based on the new findings, these statistics may change, ACSH s Dr. Gilbert Ross observes. Contrary to conventional wisdom that using more embryos per cycle would increase birth rates the data show that less may actually be more when it comes to the odds of a successful pregnancy and a reduction in complications, says Dr. Ross.