Even without the actual birth, the pregnancy becomes relevant because of how it affects people around it: the mom, the dad, their roles in the holding, their call on the holding's resources, anybody who's got a stake in the outcome. Currently, we have a newly-revealed-as-pregnant NPC in The Windmills. I figure she's about 2, maybe 3 months along. One missed period is just a thing that happens occasionally, but two is noteworthy, and three you've got a reason. So really, I've got 6 months to deal with in the fiction. If I squint just a bit, I could say each of the next 6 sessions happen a month apart, barring any that evolve into two-parters. So now I'm only looking at 10 or so sessions till the birth. Which seems fine, and plenty of time for stuff to go wrong, or to eclipse more time.
it does mean I need a calendar, as well as more maps.