Background: I have six... gaps are 17 months, 25 months, 39 months, 6 years, 40 months... so average around 3 years. The second and sixth are girls; there are about 3 years between each of the boys except the two on either side of the six-year gap. That said, there are advantages and disadvantages to each of the gaps. The smaller gaps at the beginning meant having multiples in diapers at the same time, but as they got older, they could do just about anything the other could do... the six-year gap had the advantage of the older one being pretty independent before the next baby, but it kind of felt like starting over - most of the baby stuff had been passed on by then. I think the 3-year gap is pretty ideal, really. I didn't choose the spacing, by the way, for most of them. Nursing the babies took care of that for me, except in the case of the six-year gap.