So, this astronaut comes back home from a mission on which he's unknowingly picked up some alien, you know, basic stuff.
Except he then has sex with two women, sisters, possibly twins... I think it then goes something like: they both get impregnated and the aliens erupt from their stomachs and kill him or they turn into aliens, something of that sort. I remember it being really graphic, although, I was not more than 7-10 years old.
The movie (well, the first 10 minutes of it!) obviously left me with some huge trauma since I still remember that scene, so please, be sure to reply if you know anything about it.