Question, does impregnate work automatically, or do you have to keep doing it after one time?
1. When you cum in a girl there is a chance for her to be impregnated.
2. the first week of pregnancy is stealthy. you will be unable to see it in game.
3. while a girl is pregnant it blocks progression on her quests.
4. while a girl is pregnant it blocks related girls from getting pregnant as well. So for example in your shelter, only one girl can be pregnant at a time. While the greenhouse girl is pregnant the mechanic can not get pregnant, etc
5. I am not 100% sure but I think a girl can only be pregnant once. after she has her first child (or twins) then she won't get pregnant again.
6. first week - girl is pregnant, looks normal, blocks related girls from becoming pregnant.
second week - girl is visible pregnant. announces pregnancy. can do nothing
third & fourth week - girl will have pregnant sex with you. get those scenes before you lose the opportunity
Do the rounds and creampie all of them repeatedly until they are pregnant. skip time until they will have sex with you, unlock the preg sex scenes, skip time until they give birth. Then do it again with another batch of girls