Shorter interpregnancy intervals raise odds of uterine rupture with labor after cesarean
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Key takeaways:
- Interpregnancy intervals shorter than 21 months were linked to greater odds of uterine rupture with labor after prior cesarean delivery.
- Pregnancy intervals longer than 21 months did not prevent uterine rupture.
Shorter interpregnancy intervals were strongly associated with an increase in uterine rupture in trials of labor after cesarean, according to a presenter at The Pregnancy Meeting.
“The findings will help women decide if they want a trial of labor after one previous cesarean section based on the risk of complications, especially uterine rupture, which depends on the time period from the cesarean section to the beginning of the next pregnancy,” Bradley De Vries, PhD, associate professor of obstetrics and gynecology at the Central Clinical School at the University of Sydney and head of the department of obstetrics at RPA Women and Babies, told Healio. “It also helps doctors advise women how long to wait after a cesarean section before falling pregnant again.”
De Vries and colleagues conducted a retrospective cohort study evaluating data from 499,495 births using U.S. CDC data including birth and fetal death data files from 2011 to 2021 and Period/Cohort Linked Birth-Infant Death Data Files from 2014 to 2019. All participants had one previous live birth via cesarean delivery, no previous vaginal births and an immediate trial of labor after cesarean.
Researchers evaluated the length of time from cesarean section to the beginning of next pregnancy and uterine rupture.
Rate of uterine rupture was 0.33% in the cohort. Uterine rupture rates were 0.2% with naturally occurring labor and 0.54% when labor was induced or if oxytocin was used in labor, according to de Vries. Thirty-six percent of trials of labor after cesarean delivery resulted in another cesarean delivery despite trying for a vaginal birth.
The following factors were significantly associated with uterine rupture:
- short interpregnancy interval between 0 to 21 months (each 3-month interval, adjusted OR = 0.91; 95% CI, 0.89-0.94);
- labor induction or augmentation (aOR = 2.52; 95% CI, 2.27-2.79);
- shorter maternal height per 5 cm (aOR = 0.89; 95% CI, 0.86-0.92);
- larger birth weight per 500 g (aOR = 1.17; 95% CI, 1.11-1.24);
- older maternal age per 5 years (aOR = 1.13; 95% CI, 1.07-1.18);
- higher gestational age per week from 35 to 42 weeks (aOR = 1.13; 95% CI, 1.09-1.18); and
- lower BMI per 5 kg/m2 (aOR = 0.94; 95% CI, 0.9-0.98).
Researchers observed no benefit in waiting longer than 21 months between pregnancies to prevent uterine rupture. Unplanned hysterectomy (4%), stillbirth or neonatal death (3.8%), 5-minute Apgar score more than 4 (10.1%) and neonatal seizures (2.6%) were some of the complications with higher odds of occurring following uterine rupture.
According to De Vries, moving forward, development of a clinical prediction model that could give tailored risks for individual pregnancies is needed.
For more information:
Bradley de Vries, PhD, can be reached at bradley.devries@health.nsw.gov.au.