By Jeanine Mikek, MSN, RN, RNC-NIC, CEN
Nursing Professional Development, IU Arnett Hospital, Lafayette, IN
SYNOPSIS: In this retrospective cohort study between May 2007 and April 2016, women undergoing a trial of labor after cesarean (TOLAC) were analyzed to determine if pre-pregnancy or delivery obesity status made an impact on TOLAC success. Overall, maternal body mass index did not have a significant effect on TOLAC success rates.
SOURCE: Mei JY, Havard AL, Mularz AJ, et al. Impact of obesity class on trial of labor after cesarean success: Does pre-pregnancy or at-delivery obesity status matter? J Perinatol 2019;39:1042-1049.
Cesarean births have become more prevalent in recent years and now account for nearly one-third of deliveries in the United States.1 Although not all women meet the criteria for an optimal trial of labor, choosing a vaginal birth after cesarean (VBAC) has gained attention and can lead to fewer complications. Maternal obesity as a whole can lead to several complications for both vaginal and cesarean deliveries. Although most studies in the past focus on pre-pregnancy weight, this study analyzed maternal weight at the time of delivery as well.
The authors analyzed delivery data from UCLA Medical Center between May 2007 and April 2016 to find 657 women who attempted trial of labor after cesarean (TOLAC) and had less than two prior cesarean deliveries. Six hundred fourteen women met the inclusion criteria and were categorized into four groups based on their body mass index (BMI) pre-pregnancy and at the time of delivery. In this study, 22.8% of the studied women were considered obese pre-pregnancy and 50.7% were obese at the time of delivery. Chi-squared analyses and Fisher’s tests were used to calculate statistically significant P values set at < 0.05. The overall TOLAC success rate was 72.3% and the average BMI at the time of delivery was 30.7 (class I obesity).
A higher obesity class, both pre-pregnancy and at the time of delivery, was found to be correlated with elevated blood pressure by the time of delivery (P < 0.001). Despite this complication, VBAC success rates were not affected greatly by maternal BMI, either pre-pregnancy or at delivery (rates of 71.4% to 81.8% prior to pregnancy with P = 0.91; rates of 65.9% to 74.4% at time of delivery with P = 0.75). Maternal morbidity markers and perinatal outcomes, including indications for repeat cesarean deliveries; appearance, pulse, grimace, activity, and respiration (APGAR) scores; uterine rupture; and postpartum hemorrhage also were assessed. None of these measures were greatly affected by maternal BMI at any point, since P values ranged from 0.151-0.970.
COMMENTARY
Although this study encompassed nine years of data, it was only performed at a single center, which negatively affects the ability to generalize the results because of demographic and socioeconomic variances throughout the country. Despite the fact that more than one-quarter of the women who were not obese pre-pregnancy met obesity classification at the time of delivery, there still was low representation of women who attempted a TOLAC in class II and class III (13.7% and 5.5%, respectively). There are individual variances in every labor and delivery that may not be controlled, but TOLAC success rates may be more accurate if closer to an equal amount of women were categorized in each of the four BMI classes at the time of delivery.
Obesity should not be a deciding factor when discussing the potential of a TOLAC vs. a repeat cesarean, since it has no significant difference in TOLAC success rates. TOLAC still is a safer alternative to cesarean delivery for obese women, especially when considering the additional risks of surgical complications, wound infections, and venous thromboembolisms. Women should be offered the same delivery options regardless of their BMI. However, providers should emphasize individualized care and the potential complications for the mother and fetus in the antenatal period as well as at the time of delivery. For example, gestational weight gain above recommendations made by the Institute of Medicine can lead to higher rates of cesarean birth, gestational hypertension, infant macrosomia, and a risk of shoulder dystocia.2 Measures to reduce BMI or to achieve healthy lifestyle habits should be discussed at appointments prior to confirmation of a pregnancy if possible. This recommendation may be complicated by individual barriers that would limit annual provider visits, including but not limited to finances, transportation, and scheduling. However, preventive care has more patient and financial benefits compared to reactive care for an acute or chronic issue.
REFERENCES
- Centers for Disease Control and Prevention. Births - Method of Delivery. Last reviewed April 20, 2020. https://www.cdc.gov/nchs/fastats/delivery.htm
- Simko M, Totka A, Vondrova D, et al. Maternal body mass index and gestational weight gain and their association with pregnancy complications and perinatal conditions. Int J Environ Res Public Health 2019;16:1751.
