You are the one affecting the cells; you are making a conscious action. This isn't how a pregnancy works. The parent's development is an automatic process they have very little, if any, control over. The fetus itself is actually what demands - in biological, not conscious terms - nutrients and so on from the parent body. It's involuntary. Your example is voluntary; you can stop at any time (regardless of whether or not you should). Outside of intervention (e.g. the thread topic), the pregnancy continues as far as it can, ideally to full term. You're the one who walked in here with a gotcha and didn't bother attempting to engage anyone's arguments. But you can substitute "ignorant" for "discounting relevant facts" if it helps at all.