Op, it depends on what the couples want. Do they actually want to be having children from the first year of their marriage, it's okay the lady gets pregnant first. But if they want children coming maybe after 2 or more years of marriage, there's no need getting the lady pregnant first. You see that it is purely subjective.
I totally agree with you, the question is really a subject one and whether one chooses to get pregnant before or after marriage is entirely up to them. Theirs absolutely no crime in that. In some part of the world, the males will want their partner to get pregnant first before marriage so his assured that she's fertile enough to bear him children and some males also don't want pregnancy or children before marriage. All these things all boils down to different individuals.