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, a new clinical trial recommends, the WebMD reported.

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, in N.H.

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.

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.

In the study, 154 middle-aged couples with unexplained infertility at two Boston fertility centers were randomly split into three groups. One group received oral fertility treatment, the second received injectable medication and the third went straight to IVF.

The female partner had to be between 38 and 42, and both partners had to be in relatively good reproductive health.

Within two cycles:

49 percent of those who received IVF became pregnant and 31 percent gave birth.

22 percent of those with oral medication became pregnant and 16 percent gave birth.

17 percent of those given injectable medication became pregnant and 14 percent gave birth.

All couples that had not been successful in their first two cycles of any treatment used IVF in their subsequent treatment cycles.

By the end of the treatment, 71 percent of all couples in the study had conceived a clinical pregnancy and 46 percent delivered at least one live-born baby. About 84 percent of all live births in the study came about as a result of IVF.