Women who delay having a child until their late 30s can’t necessarily rely on artificial techniques to help them become pregnant, a new study shows. The author says that assisted reproductive technologies like in vitro fertilization cannot compensate fully for the loss of fertility that occurs with age.

Based on computer calculations, Dr. Henri Leridon found that if women postpone trying to conceive for the first time from age 30 to age 35, assisted reproductive technologies (ARTs) will make up for only half of the fertility they lose over the course of those 5 years.

And for women who decide to postpone conception from 35 to 40 years, ART will make up for less than 30 percent of her lost fertility, the investigator notes in the journal Human Reproduction.

The computer model shows that, among 100 women who decide to conceive at age 35, more than 80 will naturally become pregnant. Another 4 will likely conceive after 2 rounds of in vitro fertilization (IVF), and the rest will likely remain childless, Leridon told Reuters Health.

“The message to women is: up to about 35 years, if you want a child, be patient. Even if you do not succeed in one year, your chances of success are still substantial,” Leridon said.

“Beyond that age, be impatient,” he advised.

Leridon, who is based at the French National Institute of Health and Medical Research (INSERM) in Paris, explained that some of the decline in fertility can be compensated for using ART. “But ART cannot remove all effects of age and give to a woman aged 40 years the fertility of a 20-year-old,” he noted.

To determine how well ART helps couples recover some of the fertility they lose with age, Leridon used a computer model that charted women’s chances of conceiving naturally, which gradually declined as they aged.

Based on the model, Leridon found that three-quarters of women who try to conceive naturally for the first time at age 30 will become pregnant within one year. For women who wait until 35, 66 percent will conceive within one year, and for those who start at age 40 the success rate is only 44 percent.

If women failed to conceive after 2 years, the model predicted that their chances of conception using ART would also decline with age.

“Do not wait too long before consulting for infertility,” Leridon warned, “because the effectiveness of medical techniques is also decreasing as you grow older.”

SOURCE: Human Reproduction, July 2004.