Objective
The objective was to determine the rate of neonatal brachial plexus palsy (NBPP) among women with vaginal birth after cesarean delivery (VBAC) and to compare the peripartum characteristics with control subjects.
Study Design
The Maternal-Fetal Medicine Unit cesarean registry data were used to identify nonanomalous singleton pregnancies with VBAC and NBPP at gestational age of ≥37 weeks (term) and 4 control subjects (matched for gestational age and diabetes mellitus status but without brachial injury). Odds ratio (OR) and 95% confidence intervals (CIs) were calculated.
Results
Among 11,313 VBACs at term, there were 23 women with NBPP (rate of 2.0/1000 women). Newborn infants with NBPP, compared with control infants, were significantly more likely to weigh ≥4000 g (48% vs 10%, respectively; OR, 8.45; 95% CI, 2.58–28.44) and to require admission to the neonatal intensive care unit (30% vs 13%; OR, 12.98; 95% CI, 2.61–72.18).
Conclusion
Women who desire VBAC should be informed about the low rate of NBPP and, if eligible, encouraged to have a trial of labor after cesarean delivery.
Uncommon, unpredictable, and unpreventable, neonatal brachial plexus palsy (NBPP) is defined as flaccid paresis of an upper extremity because of injury of the brachial plexus, with passive range of motion greater than active. Although most cases of NBPP are resolved, 1 in 10 persist for >1 year and may require microsurgical reconstruction. They have financial and quality of life implications and, consequently, may cause litigation.
The factors that are associated with NBPP are pregestational or gestational diabetes mellitus, precipitous second stage of labor, operative vaginal delivery, macrosomia, shoulder dystocia, or a history of shoulder dystocia. NBPP occurs in approximately 0.3 of 1000 cesarean deliveries, in approximately 1 of 1000 vaginal births; in approximately 4 of 1000 operative vaginal births, in approximately 5 of 1000 diabetic vaginal deliveries, and in approximately 19 of 1000 births if there is history of shoulder dystocia. NBPP occurs in approximately 22 of 1000 deliveries of newborn infants with a birthweight of at least 4500 g and in approximately 79 of 1000 newborn infants if the neonatal weight is ≥5000 g.
There is, however, a paucity of information regarding NBPP among women who attempt trial of labor after cesarean delivery (TOLAC) and have a successful vaginal birth after a cesarean delivery (VBAC). The Maternal-Fetal Medicine Unit (MFMU), on the basis of prospectively collected data on cesarean deliveries, TOLAC, and VBAC, have reported on brachial plexus injury but have combined it with other fetal injuries such as skin laceration, cephalohematoma, clavicular or skull fracture, or facial nerve palsy or have focused on specific clinical scenarios, such as morbidly obese women (body mass index, ≥40 kg/m 2 ) who attempt TOLAC. The American College of Obstetricians and Gynecologists practice bulletin on VBAC provides the rate of several morbidities (transient tachypnea, respiratory morbidity, hyperbilirubinemia, and hypoxic ischemic encephalopathy) with TOLAC, but not NBPP. We sought to use the MFMU cesarean delivery registry data to determine the rate of NBPP with VBAC and the factors that increase the likelihood of brachial plexus injury.
The purpose of this secondary analysis was to use the publically available data from the MFMU cesarean delivery registry data to ascertain the rate of NBPP with VBAC and to compare them with control subjects to assess whether the peripartum characteristics differ among those women with and without injury to the brachial plexus.
Materials and Methods
We obtained an approval from our Institutional Review Board (12-05-NH-0128-EVMS) to analyze the MFMU Network Cesarean Registry data that are collected by the Eunice Kennedy Shriver National Institute of Child Health and Human Development. As previously described, this observational prospective study included data on all women with a history of cesarean delivery, pregnancy at ≥20 weeks’ gestation, or whose infant’s birthweight was at least 500 g. The study was conducted in 19 clinical centers throughout the United States and was approved by the institutional review board of each participating center. Study personnel at the participating medical centers abstracted data from patient charts under a waiver of informed consent.
The labor and delivery logbook or database at each participating center was screened daily to identify all cases. Medical records for each woman and infant were reviewed by trained study nurses who were aware of the mode of delivery. Demographic data, details of obstetric history, and information about intrapartum and postpartum events were recorded. Neonatal data were collected up to 120 days after delivery or at the time of hospital discharge. Additional detailed data regarding the clinical course of all infants who were admitted to a neonatal intensive care unit were also collected.
For our secondary analysis, the cases were all singleton pregnancies that attempted TOLAC, had VBAC, were at least 37 weeks’ gestation, were cephalic, were live born, and had no congenital anomalies. For control subjects, we identified the next 4 VBAC neonates without injury and matched for gestational age (same week) and presence or absence of diabetes mellitus. Aside from the gestational age, status of diabetes mellitus, and absence of NBPP, we were unaware of the peripartum characteristics during the selection of control subjects.
Women who had pregestational or gestational diabetes mellitus were grouped together as diabetic. Term gestation was defined as newborn infants who were at least 37 weeks’ gestation at delivery, and postterm gestation was defined as those who were delivered at ≥41 weeks. Newborn infants with a birthweight of at least 4000 g were considered macrosomic. The diagnosis of NBPP was based on documentation in the chart that stated injury to the nerves of the brachial plexus with partial or complete paralysis that affected the upper extremities. The registry does not have information on whether the delivery was complicated by shoulder dystocia and how long the NBPP persisted after discharge from the hospital.
The Kolmogorov-Smirnov test was used to determine whether the data followed Gaussian distribution. The Student t test, Mann-Whitney test, and χ 2 test for independence were used where applicable. Odds ratio (OR) and 95% confidence interval (CI) were calculated. A probability value of < .05 or a 95% CI that did not cross the integer 1 was considered significant.
Results
During the study period, there were 18,054 TOLACs; among them, the rate of successful VBAC was 73% (13,259 deliveries). Of these 13,259 VBACs, 2154(16%) were excluded for the following reasons: delivery at <37 weeks’ gestation, 1985 (92%); congenital anomalies, 128 (6%); and multiple gestation, 41 (2%). Thus, 11,105 cohorts met our inclusion criteria and are the focus of the study.
The rate of NBPP was 2.0 of 1000 VBACs at term (23/11,313 cases). For other clinical scenarios, the rates with 95% CIs are presented in Table 1 .
| Variable | n | Neonatal brachial plexus palsy a | 95% CI |
|---|---|---|---|
| Vaginal birth after cesarean delivery b | 11,313 | 23 | 2 (1–3) |
| Gestational age, ≥41 wk | 1410 | 4 | 3 (1–7) |
| Diabetes mellitus c | 549 | 5 | 9 (4–21) |
| Birthweight ≥4000 g | 976 | 11 | 11 (6–20) |
| Diabetes mellitus and birthweight ≥4000 g | 67 | 4 | 60 (23–144) |
a Per 1000 vaginal birth after cesarean delivery;
b Inclusion criteria were singletons, previous cesarean delivery, gestational age of ≥37 weeks, cephalic presentation, nonanomalous, and live birth;
c Includes pregestational and gestational diabetes mellitus.
A comparison between the cases and control subjects is presented in Table 2 . The 2 groups were similar in maternal age, ethnicity, body mass index (kilograms per square meter) at delivery, and the number of previous VBACs. They also had similar cervical dilation at admission, induced or augmented vs not, and whether they did or did not have epidural anesthesia. The durations of the first and second stages of labor were also similar in the 2 groups ( Table 2 ).
| Variable | Vaginal birth after cesarean delivery + neonatal brachial plexus palsy (n = 23) | Vaginal birth after cesarean delivery + no neonatal brachial plexus palsy (n = 92) | P value | Odds ratio (95% CI) |
|---|---|---|---|---|
| Maternal age, y a | 29 (21–44) | 29 (19–44) | .801 | — |
| Ethnicity, n (%) | .429 | — | ||
| African American | 6 (26) | 36 (39) | ||
| White | 8 (35) | 30 (33) | ||
| Hispanic | 8 (35) | 22 (24) | ||
| Asian | 1 (4) | 1 (1) | — | |
| Gestational age, n (%) | ||||
| ≤40 wk a | 39 (37–42) | 39 (37–42) | — | Matched |
| ≥41 wk | 4 (17) | 16 (17) | — | Matched |
| Smoker, n (%) | 2 (9) | 17 (18) | .26 | 0.42 (0.06–2.13) |
| Alcohol, n (%) | 1 (4) | 4 (4) | 1 | 1.00 (0.04–10.39) |
| Drugs, n (%) b | 1 (4) | 7 (8) | .58 | 0.55 (0.02–4.92) |
| Body mass index at delivery, kg/m 2a | 29.86 (22.68–45.67) | 30.83 (20.7–56.48) | .572 | — |
| Maternal diabetes mellitus, n (%) | 5 (22) | 20 (22) | — | Matched |
| Previous successful vaginal birth after cesarean delivery, n (%) | 7 (30) | 34 (39) | .561 | 0.79 (0.26–2.35) |
| Cervical dilation on admission, n a | 3 (1–10) | 3 (0–9) | .185 | — |
| Type of labor, n (%) | .201 | — | ||
| Induction | 5 (22) | 36 (40) | ||
| Augmented | 11 (48) | 28 (30) | ||
| Spontaneous | 7 (30) | 28 (30) | ||
| Epidural, n (%) | 15 (65) | 67 (87) | .663 | 0.88 (0.26–2.47) |
| Duration of labor, min a | ||||
| Stage I | 445 (145–2190) | 547 (26–1712) | .639 | — |
| Stage II | 32 (0–730) | 25 (0–1335) | .090 | — |
| Operative vaginal delivery, n (%) c | 7 (30) | 0 | — | — |
| Birthweight, g a | 3975 (2850–4693) | 3322 (2770–4066) | < .001 | — |
| ≥4000 g, n (%) | 11 (48) | 9 (10) | — | 8.45 (2.58–28.44) |
| ≥4500 g, n (%) | 1 (1) | 0 | — | — |
| Apgar score <7 at 5 min, n (%) | 2 (8) | 0 | .004 | — |
| Umbilical arterial pH, n (%) | ||||
| <7.20 | 4 (17) | 2 (8) | .003 | 9.47 (1.34–81.39) |
| <7.00 | 1 (4) | 0 | — | — |
| Admission to the neonatal intensive care unit, n (%) | 7 (30) | 3 (13) | < .001 | 12.98 (2.61–72.18) |
| Other injuries, n (%) d | 4 (17) | 0 | — | — |
| Neonatal brachial plexus palsy persisted, n/N (%) e | 6/16 (37) | NA | NA | NA |
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