My answer, originally published on Quora.
Q: From a purely financial standpoint is it more expensive to have twins? Or two single pregnancies 1-2 years apart?
Keeping in mind maternity leave, nursery costs, furniture / equipment to buy and economies of scale? (I'm having twins so just curious about this.)
In the long-term, twins are probably cheaper in the USA, at least if you plan to use any amount of childcare or have your kids enrolled in lessons/activities or private schools.
The costs of strollers and clothes are inconsequential compared to the long-term cost of childcare and schooling. Most childcare situations (summer camps, daycare, afterschool care, lessons, nannies, babysitters, etc) and schools (all the way from preschool through private highschool) give you a substantial discount when you enroll two kids instead of just one.
And if the twins go to college at the same time (even to different universities), you will receive more financial aid than if their college years only overlapped by a year or two.