Family planning is essential to the health and general well-being of both mother and child (and father). An integral part of family planning is pregnancy spacing, or the amount of time between each pregnancy.

Knowing how long to wait before becoming pregnant again could have a significant impact on your next child. A study conducted by the Centers for Disease Control and Prevention (CDC) has shown that too many women are not waiting the recommended 18 months before getting pregnant with another child.

Researchers from the CDC combed through 2011 birth certificates from 36 state and the District of Columbia, which represented around 83 percent of 2011 U.S. births. This data was compared to the National Survey of Family Growth (NSFG), a national representative sample of women from 2006 to 2010. The number of months between the birth occurring in 2011 and the previous birth was calculated using the “date of last live birth” item on the birth certificate.

Findings revealed that around 30 percent of mothers became pregnant within 18 months of their previous pregnancy. Approximately 20 percent of mothers waited more than five years until their next pregnancy, while about half waited between 18 months and five years. The average time between pregnancies was two years and five months. After accounting for related factors, such as age at delivery, marital status, education, and number of previous births, the research team found that older women tend to wait the longest between pregnancies.

According to the Mayo Clinic, recent studies have tied a pregnancy within 12 months of giving birth to certain health complications, including peeling away of the placenta from the inner wall of the uterus, the placenta attaching to the lower part of uterine wall and covering the cervix, and an increased risk for autism in second-born children. Pregnancy within 18 months of giving birth is also associated with low birth weight, small size for gestational age, and preterm birth.

Source: Kirmeyer S, Thoma M, Copen C. Interpregnancy Intervals in the United States: Data From the Birth Certificate and the National Survey of Family Growth. National Vital Statistics Reports. 2015.