Cross sectional study of differences in coronary artery calcification by socioeconomic status.

Advice to couples Figure 1 may be useful for couples who wish to time their intercourse to occur during the woman’s fertile window. This approach can be improved by taking into account the regularity and usual length of the woman’s cycle (figs 2 and 3). Because we excluded couples with known infertility problems, our data do not necessarily apply to couples having trouble conceiving. Any couple wishing to have a baby can easily avoid the uncertainty of predicting fertile days by engaging in intercourse two or three times a week. Abstinence on specific days of the menstrual cycle remains a method of family planning for many couples worldwide. Women should be aware that no calendar method is completely effective. Our data suggest there are few days in the menstrual cycle during which some women are not potentially capable of becoming pregnant—including even the cycle day on which they may expect their next menses to begin.