Thanks for the suggestions everyone!
I play with aging off so my sim won’t have problems with trying to age when pregnant. I’m on my phone right now so I can’t search on the page, but I looked at retuner settings in the link and I guess I have to figure out the number of hours for different stages of the pregnancy. In the sims 4 I made pregnancy last 63 days, and I want it to be a similar length for this game. I’ll try to do some math when I’m more awake.
@igazor could I save right before my sim gives birth, and then go back and replay the day until I get the number/gender of babies I want?