Does less time between pregnancies lead to more preterm births?

June 19, 2014

Women with interpregnancy intervals (IPIs) of less than 18 months may be at increased risk of preterm delivery, according to a new study in BJOG.

 

Women with interpregnancy intervals (IPIs) of less than 18 months may be at increased risk of preterm delivery, according to a new study in BJOG.

Researchers from the University of Cincinnati College of Medicine and Cincinnati Children’s Hospital Medical Center used Ohio Department of Health records to identify singleton, non-anomalous live births ≥20 week to multiparous mothers that had occurred from 2006 to 2011. The recorded 454,716 births were grouped into IPIs of <6 months, 6 to 12 months, 12 to 18 months, and ≥18 months for comparison.

The vast majority (87%) of the deliveries followed a normal IPI ≥18 months; 10.7% had an IPI of 12 to 18 months; and 2.2% had an IPI of <12 months. A short IPI (<12 months) had a higher risk of delivery <39 weeks (adjusted odds ratio [adjOR] 2.78, 95% confidence interval [CI] 2.64, 2.93). Of the women with an IPI of <12 weeks, 53.3% delivered before their pregnancy entered 39 weeks; 37.5% of women with a normal IPI delivered before the 39th week, P<0.001. The rate of delivery at ≥40 weeks following an IPI of <12 months was smaller in comparison to a normal IPI (23.2% adjOR 0.67, 95% CI, 0.64, 0.71). The result was a  shift to the left in the frequency distribution curve of delivery  for pregnancies when the IPI was <12 months or 12 to 18 months, compared with an IPI of ≥18 months.

The investigators concluded that the data show a short IPI is associated with decreased gestational age for all births. According to their research, women with short IPIs have a higher frequency of birth in all weeks prior to 39 and fewer births at or after 40 weeks.


 

 

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