Cervical mucus features predict fertile time

NEW YORK (Reuters Health) - A woman trying to conceive a child can shorten the time to pregnancy by timing intercourse to her most fertile days based on characteristics of the cervical mucus, experts say.

Cervical mucus, which is relatively easy for women to check, is shed into the vagina, and it tends to change in amount and consistency around the time of ovulation.

When a woman is at her most fertile, the mucus is very slippery and she can sense this wetness and slipperiness, Dr. Bruno Scarpa from University of Padua, Italy, and colleagues explain in the journal Fertility and Sterility. Most women will notice a very stretchy, slippery, clear, egg-white type of mucus at this time. After ovulation, the cervix closes and the woman will notice a dry sensation, and know that she is no longer fertile.

In a study conducted at four centers in Italy that provide fertility awareness services, women kept daily records of menstrual bleeding, intercourse, and mucus characteristics. Scarpa and colleagues used these data to find "rules that maximize the probability of conception while limiting the number of intercourse days required."

The women were trained on how to identify different types of cervical mucus and sensations during their monthly cycle. Women typically have about a 6-day window every month in which they can become pregnant.

The investigators report that there were 161 pregnancies out of 2,536 menstrual cycles from a total of 191 women.

Based on the analyzed data, the researchers conclude the use of the traditional mid-cycle calendar method of determining fertile days, coupled with identification of wet, slippery, stretchy, or clear mucus, which characterizes the most-fertile type, "is very useful" for couples wanting to shorten their time to pregnancy, achieving conception without having to have sex frequently, which is impractical for some couples.

However, for couples who have intercourse on average every other day during the fertile window and occasionally during the rest of the cycle, calendar rules are sufficient, and mucus identification does not yield any added benefit.

The results apply to women with monthly cycles that run an average of 28 to 29 days, the investigators note.

SOURCE: Fertility and Sterility, October 2007.