Thursday, April 20, 2006

Space Your Babies Close Enough to Mess Each Other's Roles

A new study in the Journal of the American Medical Association says that the ideal spacing for babies is at least 18 months, but fewer than five years. Too close together and your risks of low birth weight go up, at the rate of 1.9% per month. Too far apart, though, and you start to run the risk of birth defects or sheer difficulties in having children, though co-author Dr. Agustin Conde-Agudelo acknowledges that these reasons are more speculative.

This five-year gap reminded me of another aspect of family life: birth order effects. Frank Sulloway, in Born to Rebel, says that birth order effects are strongest for siblings who are fewer than five years apart. If there is more than a five-year gap between one sibling and the next it is as if you started over, and the next kid is more like another first born.

Putting these two things together, the Expert Advice of the moment would lead to this conclusion: Have your kids far enough apart that they can occupy distinct niches (unlike "Irish twins" born nine months apart). On the other hand, don't have them so far apart that they don't shape and influence one another.

I am happy to report that the Gruntled kids just about fall within the parameters: 17 months between the first two, then four years to the next. No birth weight of birth defect problems. And they definitely influence one another's roles, in the family and in the world.


Meg said...

The biological reasons for spacing your children are compelling. I am one of three children. My sister is twenty months younger than me, and my brother is two years younger than she is. None of us were born with a low birth weight.
In addition to being born healthier, I also think that spacing your children close together is important in terms of creating a more "cohesive" family. Because we are close in age, we have a shared childhood. We always had a playmate. My mother is twelve years older than her sister, and they didn't have all the shared experiences and memories that you have with siblings close in age.

Gruntled said...

I agree. I am in the middle of a 15 year spread, and my big sister was out of the house before I was out of third grade.

sq said...

Yeah, I guess that having the five year spread between my next oldest sibling and me made at least my teen years feel like I was an only child.

Having twins, though -- neither of their birthweights was particularly low but they seem to have distinctive niches. They have a different point of view about siblings: siblings are necessarily and critical to happiness. Boy and girl siblings are preferable. (If they see an only girl child, they will ask "where's her boy?")