This is a very commonly asked question by couples trying to time intercourse so as to maximize the chance of conceiving. The answer is yes, but there is more to it. Wilcox et al. addressed this very issue in an elegant study published in the prestigious New England Journal of Medicine (N Engl J Med 1995;333:1517-21).
They studied 221 healthy women who were planning to become pregnant. At the same time the women stopped using birth-control methods, they began collecting daily urine specimens and keeping daily records of whether they had sexual intercourse. Ovulation was detected based on the hormone levels in the urine samples. Conception occurred only when intercourse took place during a six-day period that ended on the estimated day of ovulation (fertile window). (You can identify your fertile window with this easy-to-use fertility calendar.)
They further analyzed data from 129 menstrual cycles in which intercourse occurred on only a single day during the six-day period. As shown in the figure above, the maximum chance of pregnancy was when intercourse occurred on the two days prior to day of ovulation (day 0) and on the day of ovulation.
They also found that timing of sexual intercourse in relation to ovulation had no influence on the sex of the baby.
The best time to get pregnant is if you have sex within a day or so of ovulation (releasing an egg from the ovary). This period is usually when a color change is seen with many ovulation predictor kits.
