Background
Obesity in pregnancy has an impact on both the mother and the fetus. To date, no universal protocol has been established to guide the management of pregnancy in obese woman. In April 2011, the Geisinger Maternal-Fetal Medicine Department implemented an obesity protocol in which women meeting the following criteria were delivered by their estimated due dates: (1) class III obese or (2) class II obese with additional diagnoses of a large-for-gestational-age fetus or pregnancy complicated by gestational diabetes or (3) class I obese with large-for-gestational-age and gestational diabetes.
Objective
We sought to assess the impact of this protocol on the rate of cesarean deliveries in obese women.
Study Design
We performed a retrospective cohort study of 5000 randomly selected women who delivered at Geisinger between January 2009 and September 2013, excluding those who delivered in 2011. The data were stratified into obese and nonobese and divided into before protocol and after protocol. Comparison across all groups was accomplished using Wilcoxon rank sum and Pearson’s χ 2 tests. Potential confounders were controlled for using logistic regression.
Results
The cesarean delivery rate in the obese/after protocol group was 10.8% lower than in the obese/before protocol group (42.4% vs 31.6%, respectively; P < .0001). In addition, when controlling for age, race, smoking status, preeclampsia, gestational diabetes, and intrauterine growth restriction, obese women were 37% less likely to have a cesarean delivery after the protocol than they were before (odds ratio, 0.63; 95% confidence interval, 0.52, 0.76, P < .0001).
Conclusion
Implementation of a maternal-fetal medicine obesity protocol did not increase the rate of cesarean deliveries in obese women. On the contrary, obese women were less likely to have a cesarean delivery after implementation of the protocol.
Obesity, defined as a body mass index of ≥30 kg/m 2 , is an epidemic in the United States. According to the National Health and Nutrition Examination Survey 2009-2010, the age-adjusted prevalence of overweight, obesity, and extreme obesity among US women aged 20–74 years was 27.5%, 36.1% and 8.5% respectively.
In an attempt to address the ever more prominent issue of obesity in pregnancy, the Institute of Medicine and American College of Obstetricians and Gynecologists have published various papers and committee opinions discussing the risks associated with obesity in pregnancy as well as detailing recommendations for care (eg, weight gain restrictions, prepregnancy weight loss).
In addition to the increased risk of hypertension, diabetes, congenital anomalies, and stillbirth, obese gravida are at an increased risk of cesarean delivery, especially following a failed labor attempt. One study showed a significantly increased rate of cesarean delivery in moderately obese women, defined as a prepregnancy weight 90–120 kg (odds ratio, 1.60, 95% confidence interval, 1.53–1.67) and severely obese women, defined as pre-pregnancy weight >120 kg (odds ratio, 2.46 95% confidence interval, 2.15–2.81) as compared with nonobese women, defined as a prepregnancy weight of 55–75 kg.
It is evident that interventions are necessary to decrease complications associated with obesity in pregnancy. Although the Institute of Medicine and American College of Obstetricians and Gynecologists have addressed the issue of obesity in pregnancy, they have not developed specific protocols proposing the management of pregnant obese women. The Geisinger Division of Maternal-Fetal Medicine developed an obesity protocol that incorporated the recommendations outlined by Institute of Medicine, American College of Obstetricians and Gynecologists, and other literature.
The primary objective of this study was to evaluate the impact of this protocol on the rate of cesarean delivery in obese women. The secondary aims evaluated included the rate of neonatal morbidity using the following composite outcomes as surrogate markers: (1) neonatal intensive care unit admission rates, (2) the 5 minute Apgar score <5, and (3) the neonatal length of stay.
Materials and Methods
We performed a retrospective cohort study of 5000 women who delivered at the 2 major hospitals within the Geisinger Health System (Danville, PA) between January 2009 and September 2013. Deliveries in 2011 were excluded to allow for a washout period as the maternal-fetal medicine obesity protocol was instituted in April 2011.
Patients were grouped based on prepregnancy body mass index (obese vs nonobese) and delivery in relation to protocol initiation (before maternal-fetal medicine obesity protocol or after maternal-fetal medicine obesity protocol), resulting in 4 groups: (1) obese before maternal-fetal medicine obesity protocol (nonexposed group), (2) obese after maternal-fetal medicine obesity protocol (exposed group), (3) nonobese before maternal-fetal medicine obesity protocol (control), and (4) nonobese after maternal-fetal medicine obesity protocol (control). One hundred eighty-one patients were needed to detect a 10% difference in cesarean delivery rates, assuming a rate of a 33.8%, α = 0.05 and power of 80%.
The obesity protocol that was introduced in 2011 included recommendations for early gestational diabetes mellitus screening and an overall pregnancy weight gain of 11–20 pounds in all classes of obesity. A baseline 24 hour urine protein collection was recommended for class II and class III obese patients based on their increased risk of developing gestational diabetes mellitus and preeclampsia in addition to serial growth scans and nonstress tests also being utilized.
Delivery by the estimated due date was recommended for each class of obesity meeting the following criteria: (1) class III obese (prepregnancy body mass index of 40 kg/m 2 or greater) alone, (2) class II obese (prepregnancy body mass index of 35–39.9 kg/m 2 ) and a diagnosis of gestational diabetes mellitus or large for gestational age, or (3) class I obese (prepregnancy body mass index of 30–34.9 kg/m 2 ) plus a diagnosis of gestational diabetes mellitus and large for gestational age fetus. large for gestational age/macrosomia was defined as an estimated fetal weight of greater than the 95th percentile.
Five thousand women who delivered within the Geisinger Health System between January 2009 and September 2013 and who did not meet any of the exclusion criteria were included in the study. The exclusion criteria included the following: delivery in 2011, preexisting medical conditions (renal failure, chronic hypertension, pregestational diabetes); a pregnancy conceived using artificial reproductive therapy; multiple gestation pregnancy; pregnancy complicated by placental abnormalities such as placenta previa, accreta, percreta, increta, and vasa previa; prior classical cesarean delivery or prior uterine surgery; and a history of more than 2 prior cesarean deliveries.
Categorical variables were compared using the χ 2 test. Continuous variables, if normally distributed, were summarized by mean and SD and, if skewed, by median and interquartile range. Comparison across all groups was accomplished using the Wilcoxon rank sum and Pearson’s χ 2 tests. We controlled for potential confounders with logistic regression.
The rates of cesarean deliveries before and after the institution of maternal-fetal medicine obesity protocol were analyzed in both the obese and nonobese populations. We fit 2 logistic regression models to the obese patients, treating cesarean delivery as the dependent variable.
The first regression analysis included the obesity protocol as the independent variable to estimate the unadjusted effect of its implementation. The second regression analysis included the obesity protocol and patient characteristics found to be significantly related to obese/nonobese or before maternal-fetal medicine obesity protocol/after maternal-fetal medicine obesity protocol patient groups such as age, race, marital status, smoking status, gestational diabetes mellitus, preeclampsia and fetal growth restriction to control for the potential confounding factors.
The effect of protocol compliance on our findings was evaluated. Compliance was estimated by randomly selecting 97 obese (class I, II, and III) patient charts and performing a chart review. A patient was defined as compliant if specific stipulations of the protocol were followed by the provider, such as early glucola screening for all classes, nonstress tests for class II with gestational diabetes mellitus or large for gestational age and all class III obese patients, serial growth scans for class II and class III, and induction of labor prior to estimated due date for class II with gestational diabetes mellitus or large for gestational age and all class III obese patients.
We evaluated overall compliance with the protocol as well as compliance with the recommendation for induction of labor as a single stipulation. The surrogate markers for neonatal morbidity such as neonatal intensive care unit admission, Apgar scores at 5 minutes, and neonatal intensive care unit length of stay were analyzed based on before or after protocol ( Table 4 ).
| Characteristics | Before (n = 1682) | After (n = 2475) | P value |
|---|---|---|---|
| Age | |||
| Mean | 27.14 (5.5) | 27.21 (5.6) | .6987 |
| Race | |||
| Other | 80 (4.8%) | 167 (6.8%) | .0077 a |
| White | 1602 (95.2%) | 2308 (93.3%) | |
| Marital status | |||
| Married | 971 (57.7%) | 1212 (49.0%) | < .0001 a |
| Single | 711 (42.3%) | 1263 (51.0%) | |
| Tobacco use | |||
| Nonsmokers | 812 (48.3%) | 1246 (50.3%) | .0365 a |
| Smokers | 835 (49.6%) | 1200 (48.50) | |
| Drug use | |||
| Yes | 75 (4.5%) | 101 (4.0%) | .5334 |
| Delivery type | |||
| Cesarean delivery | 603 (35.9%) | 664 (26.8%) | < .0001 a |
| Vaginal delivery | 1079 (64.2%) | 1811 (73.2%) | |
| Gestational diabetes | |||
| Yes | 437 (26.0%) | 578 (23.4%) | .0529 |
| Fetal growth restriction | |||
| Yes | 99 (5.9%) | 165 (6.7%) | .311 |
| Macrosomia | |||
| Yes | 111 (6.6%) | 88 (3.6%) | < .0001 a |
| Preeclampsia | |||
| Yes | 91 (5.4%) | 103 (4.2%) | .061 |
| Arrest of dilation | |||
| Yes | 30 (1.8%) | 23 (0.9%) | .016 a |
| Failed induction of labor | |||
| Yes | 4 (0.2%) | 4 (0.2%) | .5822 |
| Length of NICU stay | |||
| Mean | 3.23 (7.7) | 3.43 (8.7) | .4518 |
| Apgar at 5 min | |||
| Mean | 8.77 (0.9) | 8.69 (1.2) | .0501 |
| NICU admission | |||
| Yes | 119 (7.0%) | 261 (10.6%) | < .0001 a |
| Variable | Obesity protocol | Before | After | P value |
|---|---|---|---|---|
| Obese pregnant women | ||||
| n | 2073 | 846 | 1227 | |
| Delivery type | Cesarean delivery | 354 (41.8%) | 387 (31.5%) | < .0001 |
| Vaginal delivery | 492 (58.2%) | 840 (68.5%) | ||
| Nonobese pregnant women | ||||
| n | 2084 | 836 | 1248 | |
| Delivery type | Cesarean delivery | 249 (29.8%) | 277 (22.2%) | < .0001 |
| Vaginal delivery | 587 (70.2%) | 971 (77.8%) | ||
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