As of v0.30 Sasha´s body is supposed to change on it´s own ...

7. Sasha body will change by itself now, body mod is an alternative way to speed up the process. (For example, if Sasha breed too much with her boobs, she will unlock an extra size as added in Ver0.2+)

After two hours in game ... and tons of violation to Sasha ... I haven´t noticed any  changes on her ...

Does she have to volunteer to Womb Modification to initialize the process ?

v0.31 - about 90 minutes in game -

Whilst retrieving the Prison Keycard on Planet 2013 ... Womb Pregnancy enabled itself ... it works ...

v0.30 no changes even on reaching Galaxy 3 ... then I updated to v0.31 ...

I would like to know more about the situation.
Are you starting a new game with Ver0.3+ or importing old saves?
Did you enabled any body mod before?

For both versions I started a fresh game ... otherwise the bodymods would have been active already ... I could have turned them off ...  but then I wouldn´t know, if the corruption works as intended ...

I didn´t count the attacks ... but Anal Pregnancy, Breast Pregnancy and Throat Pregnancy are active too by now ... guess it works like planned ...