Depends on whether you have the old or new pregnancy system selected.
This is from the Love & Sex Wiki:
Giving Birth
When a girl becomes pregnant, sometime in the next week she will have a special conversation with MC where she breaks the news. Some girls do not want children and will want an abortion. Some girls will want to keep it. If, at the end of the conversation, she decides or is coerced into keeping the child, after 9 full days her art will update to the pregnancy version. Not all girls currently support pregnancy.
As of version 22.2.0, the game now gives the player the option to choose between the old system where girls stay pregnant forever or the new system where they give birth.
- The girls give birth 60 days after they become pregnant
- If you don't marry the girl before she gives birth she will lose 25
- You'll have to pay 100 in child support every week for every baby