How do multiple births occur using fertility treatments?

The purpose of fertility treatments is to help patients conceive one baby at a time, says Karine Chung, M.D., founder and director of USC’s Fertility Preservation Program. “Fertility treatments stimulate a woman’s ovaries to produce eggs. We try to optimize the dosing of the medications, but there’s no way to control it 100 percent,” says Chung, who is also assistant professor of obstetrics and gynecology at the Keck School of Medicine of USC. “That’s the type that results in multiples—most frequently twins and triplets, and occasionally quadruplets.” She says that with the current guidelines, there’s about a 20 to 30 percent chance of twins and about a 5 percent chance of triplets.

“With in vitro fertilization (IVF), the same medications are used to stimulate women’s ovaries but instead of intrauterine insemination, we extract the eggs and fertilize them in the lab, then decide how many embryos to put back into the uterus,” explains Chung. “Typically, it’s two embryos. With three embryos, serious counseling needs to take place first.” She points out that triplets is a bad outcome; it’s not healthy for the mom or the baby.

“In IVF, you have complete control over the number of embryos that you put back into a woman’s uterus— the American Society for Reproductive Medicine has guidelines about this,” she says. In the recent case of octuplets, Chung says that if was IVF was used and the doctor replaced eight embryos, then the doctor was practicing out of the professional bounds of care.