Metformin cuts the risk of overstimulating the ovaries of women who have polycystic ovary syndrome (PCOS) and are receiving gonadotropin for in vitro fertilization, Italian researchers report in a paper online October 10 in Fertility and Sterility.
Ovarian hyperstimulation syndrome, or OHSS, is a rare iatrogenic condition in which the ovaries grow and, in advanced cases, become cystic, often causing pain and nausea.
The incidence of severe OHSS varies according to different authors, but has been reported to be up to 2% among women treated with in vitro fertilization (IVF).
In the new paper, Dr. Stefano Palomba of University “Magna Graecia” in Catanzaro and colleagues note that women with PCOS are at increased risk of OHSS.
The team studied 120 PCOS women undergoing gonadotropin ovarian stimulation for IVF. The participants were randomized to receive oral metformin 500 mg three times a day or placebo.
Stimulation length was significantly increased in the metformin group (13 versus 12 days). This was also true of the total amount of gonadotropin used.
However, there was a significant reduction in the total OHSS incidence (relative risk, 0.28; 95% CI 0.11-0.67). There were five cases of OHSS per started cycle in the metformin group and 18 cases per cycle in the placebo group.
There were no significant differences between the two groups in the rates of fertilization, implantation, multiple pregnancies and live births.
“On the basis of the current data, we can advise clinicians about metformin use in infertile patients with PCOS who are scheduled for gonadotropin in IVF cycles when they are at high-risk for OHSS,” Dr. Palomba told Reuters Health by email.
Although the mechanism by which metformin acts is still unclear, the beneficial effects found in the new study are in line with previous observations, the researchers write.
Fertil Steril 2011.
— David Douglas0