He probably didn't get them pregnant on purpose.😆 With Nandini, he was probably trying to avoid getting her pregnant, but there wasn't too much he could do short of a vasectomy (other than leave one of the women). But Nandini succeeded in getting pregnant, though she only found out after his death.
With Meera, well they probably were careless. Or their birth control failed.
Ani was probably allergic to protection 😆