Well maybe we need to change how.men and society treat women. They are are the sex that carries children for 9 months gives birth to them and are generally the ones primarily responsible for keeping children alive in their infancy ( and beyond). This makes them very vulnerable physically and economically. All of this while being treated appalling with little support or even respect for the role, from the government, other members of society or even in many cases from the fathers.
Yes of course having children is rewarding for many many women, but it is clear that in the context of a human society across the world that treats vulnerable members appalling that reward is obviously not enough for most women to offset the vulnerability, when they have a choice. You just have to look at the birth rates in countries across the globe when birth control becomes widely available
I don't know the answer but I strongly fear that women are in for a tough time as countries face steeply falling birth rates at a time whwn more and more authoritarian governments are coming to power. To be fair this has pretty much always been the case for women in the countries that never donned the veneer of equal rights for women
Equal rights for women only works in a pragmatic sense if we accept that making a choice to be a mother is more than an individual choice, it has broader consequences. It should therefore confer real societal advantage interms of real respect for the importance of the work along with economic support.
That means accepting that individual women who are more fertile may end up having economically better liveon and having more respect on aversge than if they are not . I know many will dislike that idea but I see no difference beteen being advantaged for being female and fertile or being white, male and born into money. Both are accidents of birth.
The alternative is trying to directly control women's fertility by force and coercion, which many govwenmwnts will prefer to try as simpler.
Writing to women to remind them of thier fertility window will be the the least of it,I am afraid