Ten months ago I had my second child. Two weeks ago I went in for a regular physical, and my Pap smear came back abnormal for low-grade squamous intraepithelial lesions. I am 38 years old, married and monogamous. My husband was my first sexual partner. I have never been diagnosed with a sexually transmitted disease. My kids are fine. What could have caused this to happen in these 10 months?

--Naomi

Well, first of all, you need to have a colposcopy and biopsy of your cervix to confirm that there really is an abnormality. A Pap is merely a screening test, and abnormalities on the Pap must be confirmed by tissue diagnosis (biopsy).

If biopsy does indeed agree that there is a mild dysplasia (another, easier name for "low grade squamous intraepithelial lesion"), then your doctor will discuss treatment options with you. Mild dysplasia does not necessarily demand treatment; studies have shown that left untreated, 30 percent of cases of mild dysplasia will remain the same indefinitely, 30 percent will regress to normal, and the remainder will progress. If you really have dysplasia and elect not to have treatment -- usually cryotherapy (freezing) or laser vaporization of the abnormal areas -- then you will be followed closely with Pap smears every four to six months and periodic colposcopy.

As to why this occurred, the possibilities are many. One common sexually transmitted cause of an abnormal Pap is the human papilloma virus (HPV). HPV sometimes causes genital warts, but it often lies dormant in the body for years until manifesting itself as an abnormal Pap. HPV-related changes may be noted on the Pap or on a biopsy. If you were not your husband's first sexual partner and you turn out to have evidence of HPV, he may have been exposed to it long before he met you and passed the virus on to you years ago.

But although many abnormal Paps are caused by sexually transmitted factors, this is by no means universal. Other reasons for an abnormal Pap include trauma to the cervix, such as delivery, with something going awry in the repair process; sex and therefore trauma to the cervix at a young age, while the cervical cells are immature and more prone to insult and injury; and smoking, which causes cellular damage body-wide.

Your first step is to have a colposcopy and confirm the diagnosis. The second is to have treatment, if appropriate. The third is to have regular Paps as recommended by your gynecologist thereafter.