A technique that teaches women to track their vaginal secretions cues them when they are most likely to get pregnant, and offers a “valuable addition ” to family planning, according to researchers.

As part of the “TwoDay Method,” women learn they are most likely fertile if they notice any vaginal secretions - besides blood or semen - either that day or the day before. Consequently, avoiding intercourse on those days, or using condoms or other types of birth control, should prevent a pregnancy.

Among a diverse group of women in Guatemala, Peru and the Philippines who wanted to avoid getting pregnant, those who used the TwoDay method consistently were less likely to get pregnant.

Specifically, more than half of the pregnancies that occurred during the study were conceived during cycles when women said they had had unprotected intercourse on a fertile day. One-quarter of the pregnancies occurred when women said they had avoided intercourse during fertile days.

“The main conclusion of the paper is: this thing works,” said study author Dr. Marcos Arevalo of Institute for Reproductive Health at Georgetown University in Washington, DC, which developed the method.

One advantage of the TwoDay technique is that it is natural, and women don’t have to “do anything with their bodies,” he said. Moreover, it can be used by women with irregular cycles, Arevalo told Reuters Health.

However, the method will only work if women check for genital secretions every day, and it does not protect against sexually transmitted diseases, he noted.

To investigate the effectiveness of the method, Arevalo and his colleagues followed 450 women between the ages of 18 and 39 who wanted to avoid getting pregnant for up to 13 menstrual cycles.

The researchers first explained to participants how the method worked, then asked them to keep a diary of the days they had secretions, and whether or not they had protected or unprotected intercourse on those days.

More than 96 percent of women said they had no problems detecting secretions after only one menstrual cycle, the authors report in the journal Fertility and Sterility.

According to Arevalo, after 1 year, only 3.5 out of 100 women who used the TwoDay method correctly became pregnant. This is slightly higher than the failure rate for condoms - if used correctly each time - and lower than the pregnancy rate associated with spermicides, he said.

In an interview, Arevalo explained that sperm need secretions to reach the egg and fertilize it. Without secretions, a woman is not fertile, he said. The women included in the study experienced an average of 12 “wet” days per menstrual cycle, he said.

He added that he would recommend the TwoDay method to “anybody who’s willing to check for secretions everyday, and is able to avoid sexual intercourse for a week and a half every month.”

SOURCE: Fertility and Sterility, October 2004.