Awww poor jaffers. No one’s giving him a right answer.
Ok, so There are certain times during the ovulation cycle of a woman where she is the most fertile. These are the days that are right before and right after the release of the egg from the ovary (try to remember sex-ed class now). The best time to get pregnant is during these times. Similarly, there are times during the cycle when she is not that likely to get pregnant. So, if a couple is likely to do it during the non-fertile days, then of course they won’t have babies..or well not that likely.
Similarly, not all uteruses are alike. Well, most of them are…in some cases, in order to have better chances you have to emply different positions so the sperm can have a better chance of travelling up the fallopian tubes to fertilize the egg.
There…I hope you learned something. Questions? Comments?