I relate pregnancy to population growth (ergo in the cities where civilians are and such worries matter) but as Scoutdog had to relate it to the army...
I doubt very much there will be any impact of gender/sex in the game. Surely it will be just men or if women are posssible, it'll be just a cosmetic thing. Still, considering that citizens are resources too, in theory I could draft the whole population of a town and discover that all were men!!! 
Also, if to use women in the army would have some negative impact in the population growth while adding no benefits to the army (becuase they are made equal), it would have no sense to make them join the army. In an enviroment where numbers matters* and they cannot have an edge (or forced situation) that justifies adding them to an army, they are better at their homes for the safety of that precious resource that is being able to give birth. But if women were more adept at magic, for example, it would make sense to use them whenever you want to make a unit/squad that uses magic.
* as in kingdoms were considered more powerfull the more citizens they had as, between other things, it allowed for a bigger army.