Hi, so I've talked to some people that are more knowledgeable of the game design and have ended up with this result:
- NPC has their own fertility cycle, so the chance of you hitting her up at peak fertility in a given month is at an odds that is against you.
- Even if you do manage conception, most NPC will take the morning after pill without your knowledge, to ensure no pregnancy. There is no way around this at this time, but there *are* plans to talk about birth control in a future update to go around this.
I've played around as a female character and had pregnancy fail during peak fertility during one cycle and managed to get it in the next. So for now, the best opportunity you have to experience pregnancy is through female characters.