June 18, 2004 -- After age 35, a woman's success with fertility treatments starts fading, a new study shows. Problems that make natural conception difficult will also affect in vitro fertilization attempts.
In vitro fertilization "cannot make up for ... natural decline of fertility after age 35," writes researcher Henri Leridon, PhD, an epidemiologist with the French Institute of Health and Medical Research.
Leridon's report appears in the current issue of Human Reproduction. In it, he outlines a woman's odds of giving birth -- both naturally and if she turns to in vitro fertilization later.
His complicated computer program factors in a variety of details -- how long she waits to try conceiving naturally, how many in vitro attempts she has had, her age at each attempt, her risk of miscarriage at each age, and her probability of becoming permanently sterile.
Of women trying natural conception:
- At age 30, 75% will get pregnant within one year.
- At age 35, 66% will get pregnant.
- At age 40, 44% will get pregnant.
Within four years after trying to conceive naturally:
- 91% of 30-year-olds will be successful.
- 84% of 35-year-olds will.
- 64% of 40-year-olds will.
Of women who try in vitro fertilization:
- 30% will give birth at age 30.
- 24% will at age 35.
- 17% will at age 40.
After age 35, women should "be impatient," Leridon writes. "The chances of rapid spontaneous conception are still significant, but in case of failure, [in vitro fertilization] will not fully compensate for the years lost."
"Women must have realistic expectations," says George Attia, MD, director of the In Vitro Fertilization program at the University of Miami School of Medicine. He agreed to comment on Leridon's findings. "Even though women are taking good care of themselves, that won't affect their fertility," says Attia. "They're healthy, in good shape, feel wonderful. But there's a different time clock with reproduction.
"I think it's very important for women to understand their priorities," Attia tells WebMD. "If having a child is something you're looking forward to, you shouldn't delay it. Once you cross the age of 35 and you have been trying for six months to a year, you have to be more aggressive in dealing with the issue instead of putting it on the back burner. Seek help; don't let it go another three or four years."
But don't give up hope, advises Tarum Jain, MD, reproductive endocrinology and Harvard Medical School. "In the U.S., in vitro fertilization success rates are quite a bit higher than European success rates," he tells WebMD. "That's a very important aspect of this. Success rates are dramatically different in different parts of the world."