Many couples like to space their children out so that the gap isn’t too large or too small. Usually this is because it’s easier to raise their children when they’re a similar age, but there are medical reasons for this as well. A study involving more than 11 million women was published the April 2006 Journal of the American Medical Association and it showed that women who become pregnant quickly after giving birth and women who wait for a long time to get pregnant again increase their chances of giving birth to premature babies or babies with low birth weight.

Researchers found that babies born to women who conceived less than six months after giving birth were 40% more likely to be born prematurely and they had a 61% increased chance of being born with low birth weight. This is compared with infants born to mothers who waited at least 18 months to two years between pregnancies. Also, infants whose mothers had their previous child at least five years earlier had a 20% to 43% greater chance of being born prematurely or being born with a low birth weight.

From the research conducted in the study, it looks like women who want multiple children should wait until they’re ready to have them only a few years apart. Of course this isn’t always feasible or realistic, but if you have the means to plan your pregnancies, studies show that you’re most likely to have the healthiest births when you have children that are 18 months to two years apart in age. Besides being the optimum time to have children, it will also be healthy for your kids to grow up with siblings close to their age. Siblings that have more than four years between them will probably get along better, but they won’t develop certain sibling habits that can help children learn valuable social skills.

The gap in between children also allows the mother to adjust to having a baby. For new moms this is an especially important time because having children can put a lot of stress on your body.  If you experience postpartum depression or anxiety, having another child can also make your symptoms worse. If you’re planning to have another child or if you’re already pregnant and it’s been more than five years since having your last child, make sure to talk about it with your doctor at you next appointment. You child can be perfectly healthy even with the gap, but it’s best to discuss it with your doctor just in case.


  • Zhu, B., Rolfs, R. T., Nangle, B. E., & Horan, J. M. (1999). Effect of the interval between pregnancies on perinatal outcomes. The New England Journal of Medicine, 340(8), 589-594.
  • Boyles, S. (2006, May 18). Pregnancy spacing affects outcome. WebMD.