In women, fertility declines more quickly with age. This decline becomes rapid after the age of 35.

Most women hit their fertile peak between the ages of 23 and 31

After 35 years, the proportion of women who experience infertility, miscarriage or a problem with their baby increases. By the age of 40 only two in five of those who wish to have a baby will be able to do so. This is not so for many men who can still father children past their 70s.

A new clinical trial recommends that middle-aged couples who want to have a baby but are having trouble conceiving should go straight to in vitro fertilization (IVF), skipping other types of fertility treatment.

(RELATED: What is IVF and how is it performed?)

Researchers found that women aged 38 and older were more than twice as likely to become pregnant through IVF within their first two cycles of treatment than if they used oral or injectable fertility drugs. They also were twice as likely to have a successful birth from that pregnancy.

“In this age group, time really is of the essence,” said lead researcher Marlene Goldman, a professor of obstetrics and gynecology at Dartmouth’s Geisel School of Medicine.

“Moving to a more effective treatment quicker is the way to go.”

By the end of the trial, more than four out of five babies successfully birthed had been conceived using IVF.

The normal progression of fertility treatment calls for artificial insemination combined with the oral fertility drug clomiphene first, followed by insemination accompanied by injectable medications called gonadotropins or follicle-stimulating hormones (FSH).

If those two methods fail, doctors then proceed to IVF. The mother’s egg and the father’s sperm are joined in a laboratory dish, and the resulting embryo is then implanted into the mother’s womb.

By going directly to IVF, doctors can help women in mid-life conceive despite the fact that fewer eggs are produced by the ovaries and eggs that are genetically abnormal due to their age.

Dr. Avner Hershlag, chief of the Center for Human Reproduction at North Shore University Hospital in New York says that,

“We fertility doctors should not allow our patients to age under our watch,” Hershlag said.

The study, which was funded by the U.S. National Institutes of Health, was published online April 29 in Fertility and Sterility.

The participating couples had to have been trying to conceive for at least six months, without previously using any of the treatments in the study. The female partner had to be between 38 and 42, and both partners had to be in relatively good reproductive health.