Goblins, being the randy little shits they are, tend to have quite a lot of kids at any one time. In tribes, this is/was little issue, as the whole tribe worked together to raise any kids that happened to be a part of the whole troop. Goblins who've integrated into 'civilized' society, however, quickly start to wonder if those 'Prophylactic' things the humans go on about might be worth it after all.

Also, fun fact: Goblins, although mostly sexually monomorphic, do infact grow breasts when pregnant to feed their young. It's also been noted that young goblins have very few teeth, and the first 'baby' set are all rounded. It is no coincidence than young goblins tend to be moved to solid food around the same age they adult teeth start growing in.