What do you mean by a lot of babies? Are we talking 7+ or 3, because if it's 3-4 then that's pretty standard for a single female sim if you're using the default settings in MCCC. At least, it was for me before I changed the MCCC settings.
In MCCC there's an option to set the pregnancy percentage. For instance, you can set the chance that a YA will get pregnant to 10% and change the chances of an adult getting pregnant by 5%. Just go to MCCC > MC Pregnancy > Pregnant Sim Selection > Pregnancy Percentage. Set it for 0% for all ages if you don't want random pregnancies, because the default is 20%.
MCCC also chooses who impregnates who at random if you have certain settings. Make sure your friend has set the option to bypass active romances, meaning sims in a relationship won't just get pregnant by whoever, and disallow homeless sims as eligible when a sim randomly chooses who to have a baby with.
Also, it might be helpful to turn on the notifications for all sims to alert your friend of a pregnancy. That way, if one happens, she can immediately find that pregnant sim and stop it.
