According to this article from CNBC, men are paid more in every country with women making about 80 cents compared to the man's dollar. Why is that? Supposedly, there are many factors that play into this (aside from how long someone has been with the company, what kind of experience they have, etc...). One of those factors, according to the article, is the "motherhood penalty." This phrase is described as women's earnings being negatively impacted due to raising a child while the same doesn't apply for the male. A census by the National Women's Law Center found that mothers make 71 cents for every dollar a father does.
The article suggests that maybe this is due to the fact that women are assumed to take on most of the work raising a child, searching for perks and amenities like flexible hours, in-house daycare and maybe the option to work from home. That last part is key, apparently. Most men still have jobs that require them to be in an office constantly (or on-call to come in); whereas, women may work the same amount of hours, but they're looking to work from home or have flexible scheduling, so they can be "on-call" at home. So, that's where the couples have to decide what's worthwhile. According to MarketWatch, Americans spend about $9,000 on childcare a year, which is often a large factor when searching for a "flexible" job.
Overall, there are many reasons that affect the pay gap between women and men, mothers and fathers. This was all just to lead into the question: do you take a less lucrative job to avoid daycare costs or do you do the opposite so you can pay for daycare?