https://www.miragesearch.com/health/treatment/infertility/in-vitro-fertilization
Fertility advice
You do not need to have sex all the time in order to get pregnant. If you like it that way, then no problem - it doesn't reduce a couple's fertility potential either. The best fertility advice in terms of frequency of intercourse is - every day or every other day "around ovulation".
1. Ovulation is usually on day 14 - if the menstrual cycle length (from day 1 to day 1) is 28 days, or on day 16 if periods are 30 days apart.
2. In other words, ovulation usually occurs 14 days before the next period comes.
The egg only lives about 12-24 hours, while the sperm (if normal) will live in the female's reproductive tract for up to 2-5 days - while maintaining the ability to fertilize an egg.
1. Therefore, the best fertility advice would be to have sex on the day of ovulation, or the day before ovulation (or both).
2. Having sex more than about 24 hours after ovulation should be fun and all that, but it isn't likely to increase the planetary population.
