NEW YORK (Reuters Health) – Some assisted reproduction protocols call for oral contraceptive (OC) pretreatment before ovarian stimulation, but this approach significantly reduces ongoing pregnancy rates, according to an updated meta-analysis.

“OC pretreatment is used for scheduling the date of oocyte retrieval for in-vitro fertilization,” lead author Dr. Georg Griesinger, from the University Clinic of Schleswig-Holstein in Luebeck, Germany explained. “The woman takes the OC for a time determined by her gynecologist (for example 2.5 weeks). Once the woman stops taking the pill, menstruation will occur, and ovarian stimulation treatment can be initiated.”

Without OC pretreatment, oocyte retrieval and embryo transfer cannot be predicted, he added in his e-mail to Reuters Health.

In 2008, Dr. Griesinger and colleagues published a meta-analysis of four randomized controlled trials on OC pretreatment in long gonadotropin-releasing hormone agonist protocols, published since 2006. For their updated analysis, reported online May 26th in Fertility and Sterility, they added another two trials. Using the six trials altogether, they were able to analyze pooled data on 1343 women, 670 randomized to OC pretreatment and 673 to no OC pretreatment.

All trials used combined OC pills with 30 mcg of ethinyl E2 and 150 mcg of gestogen (either desogestrel or levonorgestrel) for 14 to 28 days. The pill-free interval before stimulation ranged from 2 to 5 days. The researchers used recombinant follicle-stimulating hormone for ovarian stimulation, and either in vitro fertilization or intracytoplasmic sperm injection. Embryo transfers were performed 2 to 5 days after oocyte retrieval.

The procedures produced 141 ongoing pregnancies in the OC arm and 177 in the no OC arm (risk ratio 0.80). The number needed to harm was 20.

“I believe that the contents of the OC cause an effect on the endometrium that is still present when the embryo transfer is performed, which results in less chance of implantation after embryo transfer,” Dr. Griesinger said.

The duration of stimulation was significantly longer and the gonadotropin consumption was greater after OC pretreatment, which Dr. Griesinger attributes to suppression of endogenous gonadotropins by OC. He doesn’t believe that these factors affect pregnancy rates, however. There was no significant difference in the number of cumulus-oocyte complexes.

“Personally, I would not recommend OC pretreatment to my patients,” Dr. Griesinger said. “However, in some patients some type of pretreatment is necessary for menstruation to occur at all.”

Reference:

Fertil Steril 2010.