Characterizing vaginal misoprostol induction in individuals with and without severe obesity.
Individuals with severe obesity may experience longer labor durations and a lower likelihood of vaginal delivery compared to those with lower BMI.
Where it sits
this study against the rest of the oxytocin corpusSummary and findings
This study compared labor induction characteristics and delivery outcomes in individuals with BMI < 40 kg/m² versus ≥ 40 kg/m² undergoing induction at term. Vaginal misoprostol was administered in 25 µg doses every three hours for up to five doses. The study found that individuals with severe obesity had longer labor durations and lower odds of vaginal delivery.
Abstract
<h4>Objective</h4>To compare labor induction characteristics and delivery outcomes among individuals with body mass index < 40 versus ≥ 40 kg/m<sup>2</sup> undergoing induction at term.<h4>Study design</h4>This secondary analysis utilized data from the vaginal misoprostol arm of a cluster randomized controlled trial comparing vaginal to oral misoprostol for induction. Individuals at ≥ 37 weeks gestation with cervical dilation ≤ 2 cm undergoing induction using a standardized protocol were included. Vaginal misoprostol was given in 25 µg doses every three hours for up to five doses, followed by a standardized oxytocin protocol. We compared labor progression among individuals with BMI < 40 and ≥ 40 kg/m<sup>2</sup> at delivery, including labor duration, misoprostol use, and obstetric and neonatal outcomes. Generalized estimating equations were used to account for clustering and comorbid conditions. Effect sizes were presented as odds ratios and adjusted mean differences with 95% confidence intervals.<h4>Results</h4>From May 2021 to September 2022, 1,322 patients received vaginal misoprostol for labor induction at term. Among these, 1,058 (80.0%) had a BMI < 40 kg/m<sup>2</sup> and 264 (20.0%) had a BMI ≥ 40 kg/m<sup>2</sup>. Individuals with severe obesity were more likely to start induction with a closed cervix. After adjustment for clustering, initial cervical dilation, hypertension, and diabetes, inductions in the group with severe obesity had longer total durations (adjusted mean difference 3.5h, 95% CI 1.9-4.8), first stage of labor (adjusted mean difference 2.2h, 95% CI 0.6-3.8), and duration of oxytocin use (adjusted mean difference 2.5, 95% CI 1.1-3.8). Individuals with BMI ≥ 40 kg/m<sup>2</sup> also had lower odds of vaginal delivery (aOR 0.6, 95% CI 0.4-0.8) and required more doses of misoprostol for induction.<h4>Conclusion</h4>Severe obesity, defined as BMI ≥ 40 kg/m<sup>2</sup>, is associated with longer time to delivery, increased misoprostol requirement, longer duration of oxytocin use, and lower odds of vaginal delivery compared to individuals with lower BMI. Consideration of alternative labor induction protocols must be balanced with increased comorbidities and overall obstetric morbidity in this group.
Background
The paper addresses the impact of severe obesity on labor induction outcomes, a critical area given the rising prevalence of obesity and its implications for maternal and neonatal health. Previous studies have indicated that obesity can complicate labor and delivery, but specific comparisons between different BMI categories have been limited. This study is significant as it utilizes a large sample size to explore these differences in a controlled setting.
Methods
This secondary analysis utilized data from a cluster randomized controlled trial comparing vaginal to oral misoprostol for induction. The population included individuals at ≥ 37 weeks gestation with cervical dilation ≤ 2 cm, receiving vaginal misoprostol in 25 µg doses every three hours for up to five doses, followed by a standardized oxytocin protocol. Generalized estimating equations were used to account for clustering and comorbid conditions.
Results
The primary endpoint indicated that individuals with BMI ≥ 40 kg/m² had an adjusted mean difference of 3.5 hours longer total duration of induction (95% CI 1.9-4.8) compared to those with BMI < 40 kg/m². Additionally, they experienced longer first stage of labor and increased oxytocin use, with lower odds of vaginal delivery (aOR 0.6, 95% CI 0.4-0.8).
Interpretation
These findings suggest that severe obesity is associated with longer labor durations and increased intervention requirements, aligning with previous literature that indicates obesity complicates labor. However, the effect sizes, while statistically significant, may not be clinically meaningful in all contexts. Limitations include potential confounding factors due to the observational nature of the study and reliance on a single trial's data.
Key findings
- 1,322 patients received vaginal misoprostol for labor induction at term.
- Individuals with BMI ≥ 40 kg/m² had an adjusted mean difference of 3.5 hours longer total duration of induction (95% CI 1.9-4.8).
- Individuals with BMI ≥ 40 kg/m² had an adjusted mean difference of 2.2 hours longer first stage of labor (95% CI 0.6-3.8).
- Individuals with BMI ≥ 40 kg/m² had an adjusted mean difference of 2.5 more hours of oxytocin use (95% CI 1.1-3.8).
- Individuals with BMI ≥ 40 kg/m² had lower odds of vaginal delivery (aOR 0.6, 95% CI 0.4-0.8).
Limitations
- Observational analysis may introduce confounding factors.
- Data derived from a single trial.
- Potential impact of comorbidities not fully explored.