To put that into further perspective, it costs us about $20000/year for day care for our baby. This is near Boston.
If one parent in a situation like this is making around the median individual income of ~$40k a year, it probably makes more sense financially to not work until the kid is school age.
Obviously it's not that simple because of potential lost future earnings resulting from delayed career advancement, but I wonder if people really bother doing the math.