The best time to get pregnant and have sex intercourse is the so-called "fertile fertility window." The fertile fertility window extends for 6 days starting at 5 days before ovulation until the day of ovulation. Your most fertile days are the 1-2 days before and the day of ovulation. Calculate the Fertility Window HERE
Many studies have been published over the years in the attempt to understand the factors that influence fertility and the process of conception.
The fertile window which is the best time to get pregnant has been defined as the days of the menstrual cycle during which intercourse is most likely to result in pregnancy. This fertile window extends for 6 days starting at 5 days before ovulation until the day of ovulation. Your fertile days are the 4-5 days before and the day of ovulation, but the most fertile days are just the 2 days before and the day of ovulation.
Sexual intercourse the day after established ovulation is unlikely to improve your chances getting pregnant. and chances getting pregnant if you make love after ovulation is nearly zero.
Increasing amounts of estrogen in the cervical mucus and reproductive tract of a women approaching ovulation generally allows the sperm to live for up to 6 days.
Studies have shown that even in women with regular cycles, ovulation can possibly happen any time, so "timing" of intercourse and trying to answer the question when is the best time to get pregnant has never been shown to significantly improve your pregnancy chances. You are probably not improving your chances of getting pregnant if you wait with intercourse until the temperature goes up or the OPK has become positive. You may already have ovulated by that time, and sex after ovulation is unlikely to get you pregnant.
Couples who tried to get pregnant were previously told to have sex once every other day during their fertile days. Recent studies have shown that for the average couple who is trying to conceive the best time to get pregnant is that they should make love regularly 2-3 times a week, every week because you don't know exactly when ovulation happens.
In addition, you may improve your chances if you have sex once a day (as long as his sperm are OK) during the fertile 4-5 days prior to, and the day of, ovulation. In those rare circumstances when the man does not have enough sperm (oligospermia), the old rule of once every other day still holds true.
Sex during fertile days: % Pregnancy
From: "Timing of Sexual Intercourse in Relation to Ovulation -- Effects on the Probability of Conception, Survival of the Pregnancy, and Sex of the Baby" was published in The New England Journal of Medicine (December 7, 1995 -- Vol. 333, No. 23). Allen J. Wilcox, Clarice R. Weinberg, Donna D. Bair