The wage (and income) gap exists entirely within households. Young single women currently earn more than young single men. Never married women have always earned as much as never married men.

So you're in a marriage and your partner comes home to say "Honey, I just got a big raise!"

Do you reply: "Turn that down! It exacerbates our household wage gap!"? 

Or, do you say "Great! Let's finally buy a new car!" Or, "Great! Maybe I can go down to four days a week and spend more time with the kids!"

There are increasing numbers of men staying home with children because their partners can earn more money than them. In these households there is a wage gap the other way. Who cares? It's household income. Everyone in the household contributes in the way that makes the most sense.

Infertile couples will make incredible sacrifices to have children. It's not a "burden" to be able to stay home with them. It's an expensive privilege, mostly enjoyed by women.