Debate about the alien at the end of the movie.

"..had Shaw been already say 3 months pregnant then got infected ." THis is a pivotal plot point and one that I don't think has been mentioned. Assuming that Shaw Holloway have had relations prior to the start of this journey she could have been already with child so to speak. It is hard to believe she somehow became pregnant during the trip , in statis, and when the infected Holloway had his way with Shaw(Did anybody else think thyat Holloway sort of forced himself on a very emotional vulnerable Shaw at this point of the story) . Of course she did have 'morning sickness' when David wakes her up.