Where I live (~DC), daycare costs 2.2k per month. With two kids and a 35% marginal tax rate (including state taxes and Medicaid/etc) you would need to make $81k per year just to break even.

Add up extra food costs (vs cooking at home) and extra cleaning costs ($140 every two weeks so about $4k and the value prop of having one SAH parent doesn't look as bad (which is what several college-educated friends have done, sp the ones with 2+ kids)