I would imagine that once you start to look outward, see outside of yourself in seeking meaning, what it all means, what life means to you, that you would start to see what path(s) are right for you in feeling any particular fulfillment. Given that we all have this biological time bomb built within us and a feeling or "need" to reproduce, how else can a species survive without such coded need, I would assume that the two (this biological need to reproduce and the personal path towards self fullfillment) would naturally cross paths at one point or another. Whether this direction is accurate, meaning, whether having children aligns with one's path of self fulfillment is indeed true and not muddied or confused, with what is true, is something that has to be realized on an individual basis. I take it, that if by the time that ticking time bomb occurs before the individual realizes their path or understands themself to a point of knowing what will give them the utmost satisfaction in life, then the void will be filled with child bearing as a sort of "convenience", mixed in with potential external, social pressure.
Who knows really, just thinking off the cuff here.