Over-stimulated ovaries occurred in 154 out of every 10,000 pregnancy attempts; rates of other complications were less than 10 per 10,000 attempts. There were 58 deaths reported during the 2000-11 study. The study lacks information on their causes, and with more than 1 million pregnancy attempts involved, the results are reassuring, said Dr. Jennifer Kawwass, an Emory University assistant professor and the lead author.
The study is the first large-scale effort to quantify risks for U.S. patients undergoing these treatments, Kawwass said. Results were published in Tuesday's Journal of the American Medical Association.
The researchers examined federally mandated reports from U.S. fertility clinics.
The fancy term for treatments involved is assisted reproductive technology, the shorthand is IVF. It refers to in vitro fertilization — mixing eggs and sperm in a lab dish. Any resulting embryo or embryos are then transferred to the uterus. A type of IVF involving injecting a single sperm into an egg was included in the study.
Fertility drugs are used with IVF to stimulate ovaries to produce eggs. High doses can cause swollen ovaries and mild abdominal bloating. Severe cases may involve persistent pain, substantial weight gain, vomiting and dangerous blood clots.
The data includes women using their own eggs and those donating eggs.
MORE ON COMPLICATIONS
Deaths included 18 within 12 weeks of starting fertility drugs — suggesting the drugs might have played a role. The other 40 deaths occurred later, suggesting pregnancy-related complications might have been involved; 18 of these women were carrying twins, triplets or more. The reports don't list exact causes of death.
Rates for over-stimulated ovaries didn't change during the study but rates for other medicine side-effects and hospitalizations declined. Stable rates were seen for other problems, including infections, bleeding and anesthesia complications.
Complications were most rare in donors, who typically are healthy young women, and none died.
WHAT EXPERTS SAY
Dr. Richard Paulson, vice-president of the American Society for Reproductive Medicine, said many complications and deaths could have been from underlying conditions causing infertility, rather than the treatments.
Doctors in recent years have limited the number of embryos transferred, to reduce chances for unsafe multiple births. Paulson, director of the University of Southern California's fertility program, said the move could lead to a decline in some complications including those related to over-stimulated ovaries.
Dr. Jamie Grifo, director of New York University's fertility centre, noted that about 2 per cent of U.S. babies are born from IVF, and said the study confirms that risks facing women undergoing the procedure are small.
AP Medical Writer Lindsey Tanner can be reached at http://www.twitter.com/LindseyTannerSuggest a correction