Additional side question...with higher mortality rates and shorter life expectancy it made sense for most couple to get started in the child bearing process sooner rather than later.
For royals who were desperate for (male) heirs, yes, but not for most people, who rather wanted to limit the numbers of mouths to feed and the number of heirs sharing an inheritance / farm / livelihood. One of the traits that made Western Europe stand out from the rest of the world and spearhead modernity (and romantic love?) was exactly this pattern of late marriage (mid to late 20s) and a significant minority remaining lifelong singles and thus fewer children, who were better provided for. See https://en.wikipedia.org/wiki/Western_European_marriage_pattern
. Russia and European royalty were in this respect "east of the Hajnal line", while you can observe the pattern very well in Norwegian peasants before industrialisation, with mothers as young as Alexandra Pavlovna being very uncommon and mostly tragic cases of out-of-wedlock births, arranged marriages for very rich heiresses (early marriage as some kind of status symbol or pawn in alliance building) or other odd circumstances.
Most peasant girls and boys worked for a few years in their teens and early 20s as maids and farmhands (and engaged in nattefrieri
, night courting, i.e. all kinds of romantic sleepovers, heavy petting and probably oral sex etc. without full intercourse), saved money and didn't marry (someone more or less of their own choosing) untill they could support a family, which could be the stereotypical 10-15-20 children where half of them died in infancy, but just as likely 5-6-7, where most survived. Upper-class women who did not breastfeed their babies themselves were probably fertile more often than peasant women, whose fertility was not only limited by their later marriage, but also by breastfeeding.
That said was their thought given at the time to a young woman's age and how that could be a benefit or detriment in having a healthy pregnancy?
I'm sure there was, but as with Semmelweis's case I'm sure there were very conflicting opinions.