Biological male draft has always made sense from a population maintenance standpoint. If you did a biological female draft only you'd see an even more massive population drop from any hot war that you see with a male-only draft.
So X people dead in war led to 2X people not reproducing. If the draft had been 50/50, then X dead would have only led to X not reproducing.
Quoting https://www.reddit.com/r/AskHistorians/comments/dv3u8t/what_...
"The shortage of men also meant a very important shift, in which the Soviets worked to try and both destigmatize single-motherhood by increasing state benefits they could receive and featuring mothers of ambiguous marital status in propaganda, while also tacitly encourage even married men to sleep around by preventing the single mothers from suing the father for child support, and making it harder for their irate wives to divorce them. The result being that many men would have numerous affairs, and even unmarried men would often bounce from relationship to relationship."
The interbellum period in France and Germany also saw an increase in sexual freedom leading to more single mothers, without going to polygamy.
Most societies are polygamous when you look in terms of sex and reproduction, even if they aren’t when it comes to socially recognized family bonding.
> In monogamous societies like the UK the deaths of many men in the world wars led to "marriage gaps" where a roughly equivalent number of women were unable to marry and have children.
Unable to marry, maybe, unable to have children, less so, hence the spike in unmarried share of births around the end of WWII (probably even moreso in WWI, too, but the information I have starts in the 1920s.)
Not so much a greater immediate drop as a much slower bounce back.