Since I am pregnant with my second child – a boy! – there is only one detail that has been bothering me: the age difference. My firstborn will be six Years older than my newborn, which feels light years ahead developmentally. Will they still fight over toys? Fight for their parents’ attention? Maintain a close bond? These are just some of the Care for Questions are buzzing through my head.
That’s when I came across a new and surprising study: According to a 2020 study that analyzed fertility rates in modern times, larger age gaps between siblings are becoming more common. This, in turn, could change family dynamics (and birth order)—and not in a bad way.
First, a quick look at the data: Between 1967 and 2017, the gap between births of siblings widened only minimally—about three-quarters of a year. By comparison, today 22 percent of mothers have their children six or more years apart, according to the study. Research shows that siblings are still about four years apart on average, but today’s fertility resources (not to mention a changing definition of the American family since the 1960s) are causing that gap to widen more quickly.
For example, couples who want children now have access to contraception (which means they have more control over planning their pregnancies), and there are services such as IVF that can help extend the childbearing window and ease the difficult road to fertility. Added to this are changing family dynamics. Life experiences such as divorce and remarriage (also known as multi-partner fertility) are other factors that can also lead to a larger age gap between siblings.
In addition, the birth rate is declining for a number of reasons: women are waiting longer to have children and are also choosing to have fewer children. (I’ll briefly touch on the lack of support for working parents here.) Whatever the reason, if you’re not planning on having five babies, that’s another factor that reduces the rush to have them one at a time.
But now to the bigger question, which goes back to my original concern: If age differences Are What impact will this have on sibling relationships and children’s personalities in the future?
To find out, I consulted Dr. Laurie Kramer, a licensed clinical psychologist and professor of applied psychology at Northeastern University, where she directs the Siblings Research Group. (She is also founding director of the Family Resiliency Center at the University of Illinois.)
