Dr. Mary Schooling, a professor at the CUNY School of Public Health, along with colleagues from China examined the effect of interpregnancy interval on adverse perinatal outcomes in China. The work was published in the journal Paediatric and Perinatal Epidemiology.
[Photo: Dr. Mary Schooling]
In January 2016, China introduced a universal two-child policy. The research team investigated the effect of interpregnancy interval after live birth on the risks of preterm delivery, and small, and large for gestational age births in China.
The research team conducted a cohort study among 227, 352 Chinese women with their first and second delivery during 2000 to 2015. They calculated Interpregnancy interval as months from first live delivery to conception of the second pregnancy. Poisson regression models with robust variance were fit to evaluate associations of interpregnancy interval with risk of adverse perinatal outcomes, adjusted for potential confounders.
Compared to interpregnancy interval of 24- <30 months, interpregnancy interval <18 months was associated with higher risks of preterm birth and small for gestational age. For interpregnancy interval <6 months, the adjusted relative risks for preterm birth and small for gestational age were 2.04 and 1.43, respectively. Women with interpregnancy interval ≥60 months had higher risks of preterm birth and large for gestational age. For interpregnancy interval ≥120 months, the adjusted relative risks for preterm birth was 1.67 and for large for gestational age was 1.10.
The authors concluded that women with interpregnancy interval <18 months after live birth had higher risk of preterm birth and small for gestational age, and if the interpregnancy interval were ≥60 months there was an association with higher risk of preterm birth and large for gestational age. These findings may provide information to Chinese couples about the appropriate interpregnancy interval for a second pregnancy.