My husband and I have been trying to get pregnant for over a year and have begun infertility testing. I have read that some doctors are now treating women with antibiotics before trying more expensive and difficult therapies, when there aren't obvious reasons for infertility. We tested positive for ureaplasma and are on antibiotics. Is there a chance that this will help us conceive?

J.S.

I agree that a course of antibiotics may be advisable. However, it's important to note that there is no credible reproducible evidence to suggest that infection with ureaplasma or some as-yet undefined organism is the major cause of unexplained infertility.

Unexplained infertility is just that -- unexplained. That means many of these couples are not infertile. Rather, they are subfertile, meaning that each month they may have a 3-10 percent chance of conceiving without any treatment or intervention at all. Since studies suggest that chronic undetected infection is a rare cause of infertility, many of these successes that are reported in couples who have undergone antibiotic therapy are probably coincidental. Moreover, existing studies do not support the use of antibiotics as a SINGLE treatment for unexplained infertility. Well designed placebo- controlled trials would be needed to support this approach.

Ureaplasma urealyticum (UU) is a type of organism that is, both in size and character, somewhere between a bacteria and a virus. UU is a fairly common organism that may be found in up to 30 percent of those tested in certain populations. It can be passed sexually, but its presence should not initiate a call to a divorce lawyer, because you can get it in other ways as well. Testing for UU is expensive, and cultures often demonstrate a falsely negative result even if you are infected.

The prevalence of UU in people suffering fertility problems is no greater than in those who have no fertility problems, and treatment does not seem to improve fertility rates. The one case in which treatment may be beneficial is for couples with recurrent pregnancy loss. Here, due to expense and the poor reliability of UU testing, I prefer to routinely treat these couples with a 10-day course of antibiotics. The data are inconclusive, however, and more recent well designed studies have not shown benefit.

On the other hand, frequently our patients have a positive blood antibody response to chlamydia infections, even when a DNA test done from a cervical swab indicates no present infection. The positive blood antibody test means that an infection was present at one time. Most of these women are not aware they ever harbored this infection, which can damage the fallopian tubes. Because chlamydia can be present in the fallopian tubes and not show in the cervical swab tests, I believe that antibiotic treatment may be beneficial to address the possibility of an infection in the tubes. However, the benefits of testing and treatment for infections other than gonorrhea and chlamydia is small or non-existent.