A new study found that for mothers who wait less than 18 months to become pregnant again, the ensuing pregnancy is shorter.
Published in BJOG: An International Journal of Obstetrics and Gynaecology, the study examined interpregnancy intervals (IPIs) from 454,716 live births of mothers who experienced two or more pregnancies over a period of six years.
Subjects were divided into three categories according to their IPIs. The shortest IPI category consisted of those under 12 months, next came 12 to 18 months, and finally an IPI of over 18 months, considered by the researchers to be optimal.
Results concluded that mothers with the shortest IPIs were likely to give birth before their 39th week, which could lead to problems even though the CDC considers pre-term birth as occuring before 37 weeks.
According to the CDC, women seeking to schedule their births should elect to do so after the 39th week to avoid the problems associated with pre-term birth such as sensory and feeding problems as well as cerebral palsy.
"Short interpregnancy interval is a known risk factor for preterm birth, however, this new research shows that inadequate birth spacing is associated with shorter overall pregnancy duration," said Emily DeFranco, Assistant Professor of Maternal-Fetal Medicine at the University of Cincinnati College of Medicine in Ohio and the Center for Prevention of Preterm Birth at Cincinnati Children's Hospital Medical Center, and co-author of the study.
Mothers in the shortest IPI category of under 12 months delivered before 39 weeks at a rate of 53.3 percent. Women in this category were twice as likely to deliver before 37 weeks.
For women in the second and third categories, the rate dipped to 37.5 percent.
"This study has potential clinical impact on reducing the overall rate of preterm birth across the world through counselling women on the importance of adequate birth spacing, especially focusing on women know to be at inherently high risk for preterm birth," said DeFranco.