Pregnancy and the Timing of Intercourse

This article has no abstract; the first 100 words appear below.

To the Editor: Wilcox et al. (Dec. 7 issue)¹ reported that among 221 women who were attempting to become pregnant, conception occurred only during a six-day period that ended on the day of ovulation. This study provides excellent information for women who are trying to conceive. However, these data are probably not applicable to the large number of women who are trying to avoid pregnancy or having unprotected intercourse but who do not want to become pregnant. These women are much more likely to have intercourse outside the six-day fertile period and thus are more likely to conceive outside that . . .