Methotrexate May Cut Oocyte Yield After Ectopic Pregnancy


INDIAN WELLS, CALIF. — Methotrexate is a safe and effective alternative to surgery for ectopic pregnancy; however, it may temporarily interfere with the success of fertility treatment, Dr. Janet McLaren reported at the annual meeting of the Pacific Coast Reproductive Society.

Significantly fewer oocytes were retrieved in cycles within 180 days of methotrexate-treated ectopic pregnancy, compared with cycles attempted beyond 180 days, in a study of 35 patients.

With patients serving as their own controls, the mean number of oocytes obtained in cycles in the first 6 months following methotrexate treatment of ectopic pregnancy was 7.8, compared to 10 during cycles performed before they received methotrexate.

Beyond 6 months, there was no reduction in the number of oocytes retrieved per cycle.

A slight decrease in endometrial thickness was also noted in the first 180 days following exposure to methotrexate, which targets rapidly dividing cells.

A total of 48 patients underwent fertility treatment following exposure to methotrexate in the chart review performed by Dr. McLaren and associates at Brigham and Women's Hospital and Harvard Medical School, both in Boston, and Stanford (Calif.) University Medical Center.

(Not all women underwent similar infertility procedures before and after methotrexate administration, and some lacked comparable pre- and postmethotrexate data, so not all subjects were included in the oocyte and endometrial thickness comparisons.)

Among the entire cohort of 48 patients, 18 (37.5%) achieved an intrauterine pregnancy within a year, and 5 more women became pregnant with assisted reproductive technologies more than a year following methotrexate exposure, for a total overall pregnancy rate of 48%. Four of 48 women (8.3%) experienced a recurrent ectopic pregnancy. The mean time to conceive after methotrexate administration was 246 days.

Dr. McLaren concluded that her small study suggests there is a “time-limited effect on oocyte yield.”

“If this is confirmed in larger series, it may be advisable to defer fertility treatment for 6 months after methotrexate administration,” Dr. McLaren commented.

Of course, delaying reinitiation of fertility treatment would be less appealing to women who have an ectopic pregnancy at 39 than to women who have one at age 32, she noted.

Asked by an audience member whether fertility patients should undergo surgical treatment of ectopic pregnancy to avoid methotrexate exposure, Dr. McLaren replied, “The decision to do surgery versus methotrexate is so individual for each patient: what her operative risk is, and how anxious they are to get it over with. I have to say it's a case-by-case basis.”

She noted that only five fertility patients underwent surgery rather than medical treatment of ectopic pregnancy in the Brigham and Women's Hospital program over a 6-year period.

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