Quora: Is it more expensive to have twins or two single pregnancies?

My answer, originally published on Quora [http://www.quora.com/From-a-purely-financial-standpoint-is-it-more-expensive-to-have-twins-Or-two-single-pregnancies-1-2-years-apart/answer/Sue-Raisty] . 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,…