Abstract
BACKGROUND:
Hypertensive disorders of pregnancy are the leading cause of indicated preterm birth; however, the optimal delivery approach for pregnancies complicated by preterm hypertensive disorders of pregnancy remains uncertain.
OBJECTIVE:
This study aimed to compare maternal and neonatal morbidity in patients with hypertensive disorders of pregnancy who either went induction of labor or prelabor cesarean delivery at <33 weeks’ gestation. In addition, we aimed to quantify the length of induction of labor and rate of vaginal delivery in those who underwent induction of labor.
STUDY DESIGN:
This is a secondary analysis of an observational study which included 115,502 patients in 25 hospitals in the United States from 2008 to 2011. Patients were included in the secondary analysis if they were delivered for pregnancy associated hypertension (gestational hypertension or preeclampsia) between 230 and <330 weeks’ gestation; and were excluded for known fetal anomalies, multiple gestation, fetal malpresentation or demise, or a contraindication to labor. Maternal and neonatal adverse composite outcomes were evaluated by intended mode of delivery. Secondary outcomes were duration of labor induction and rate of cesarean delivery in those who underwent labor induction.
RESULTS:
A total of 471 patients met inclusion criteria, of whom 271 (58%) underwent induction of labor and 200 (42%) underwent prelabor cesarean delivery. Composite maternal morbidity was 10.2% in the induction group and 21.1% in the cesarean delivery group (unadjusted odds ratio, 0.42 [0.25–0.72]; adjusted odds ratio, 0.44 [0.26–0.76]). Neonatal morbidity in the induction group vs the cesarean delivery was 51.9% and 63.8 %, respectively (unadjusted odds ratio, 0.61 [0.42–0.89]; adjusted odds ratio, 0.71 [0.48–1.06]). The frequency of vaginal delivery in the induction group was 53% (95% confidence interval, 46.8–58.7) and the median duration of labor was 13.9 hours (interquartile range, 8.7–22.2). The frequency of vaginal birth was higher in patients at or beyond 29 weeks (39.9% at 240–286 weeks, 56.3% at 290–<330 weeks; P=.01).
CONCLUSION:
Among patients delivered for hypertensive disorders of pregnancy <330 weeks, labor induction compared with prelabor cesarean delivery is associated with significantly lower odds of maternal but not neonatal morbidity. More than half of patients induced delivered vaginally, with a median duration of labor induction of 13.9 hours.
Keywords: cesarean delivery, induction, preeclampsia, prematurity
Introduction
Hypertensive disorders of pregnancy are the leading cause of indicated preterm birth and accounts for 25% to 43% of all preterm births.1–3 The optimal delivery approach for pregnancies complicated by preterm hypertensive disorders of pregnancy remains uncertain, with studies citing a vaginal delivery success rate of 1.8% to 80% following induction of labor (IOL) at <28 weeks for preeclampsia.4–6 Most patients requiring preterm delivery do not have favorable cervical exams and as a result, some providers advocate for prelabor cesarean delivery owing to concern for worsening hypertension during labor induction and the potential for increased maternal and perinatal morbidity, particularly in the setting of severe hypertensive disease.5,7–9 Previous studies have suggested that in the setting of preeclampsia with severe features labor induction is associated with better neonatal morbidity, whereas other studies have shown no difference.4,5,10 No differences in maternal morbidity have been attributed to the mode of delivery in the setting of preeclampsia, although the numbers are small.4
Our objective was to compare maternal and neonatal morbidity in patients with hypertensive disorders of pregnancy (gestational hypertension and preeclampsia) at <33 weeks who underwent an IOL compared with those who underwent prelabor cesarean delivery, and to quantify the duration of labor induction and rate of vaginal delivery. Subanalyses were done to evaluate the characteristics associated with the duration of labor induction and the rate of vaginal delivery. We hypothesized that compared with prelabor cesarean delivery, IOL was associated with a lower neonatal and maternal morbidity.
Materials and Methods
This is a secondary analysis of the Assessment of Perinatal EXcellence [APEX] study involving 25 hospitals in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. Data on demographics, intrapartum events, and pregnancy outcomes were collected by trained certified nurses from 115,502 patients with a live fetus >23 weeks’ gestation who delivered during the 24-hour period of randomly selected days between 2008 and 2011. Institutional review board approval for the study and a waiver of informed consent was obtained at all centers. Full details of the primary study have been described previously in the original study publication.11
Patients were included in our secondary analysis if they had a singleton vertex pregnancy and with the indication for delivery being hypertensive disorders of pregnancy between 240 and <330 weeks’ gestation. Hypertensive disorders of pregnancy were defined as gestational hypertension, preeclampsia, eclampsia, or HELLP (hemolysis, elevated liver enzymes, low platelet count) syndrome because we wanted to evaluate any patients with hypertensive disorders of pregnancy severe enough to require delivery. Definitions of hypertensive disorders of pregnancy were not standardized within the data set but were based on institutional interpretation of the American College of Obstetricians and Gynecologists definitions and recommendations at the time of enrollment.12 Exclusion criteria included fetal anomalies, spontaneous labor, ≥2 previous cesarean deliveries, or other contraindications to labor such as nonreassuring fetal status, placenta previa, placenta accreta, maternal health concern, or previous cesarean delivery with a vertical uterine incision into the contractile portion of the uterus.
The study groups were composed of patients who underwent an IOL or those who underwent a prelabor cesarean delivery. Analysis was done with the intention to treat rather than mode of delivery. The primary outcome was a maternal morbidity composite of maternal death, hysterectomy, sepsis, venous thromboembolism, intensive care unit (ICU) admission, surgical procedures other than cesarean delivery or postpartum tubal, cerebral vascular event, pulmonary edema, disseminated intravascular coagulation, blood transfusion, blood loss >1500 cc, endometritis, wound infection requiring antibiotics, and wound requiring reoperation.
A neonatal adverse composite outcome was also constructed consisting of neonatal death or intrapartum stillbirth, subgaleal hemorrhage, intraventricular hemorrhage grade 3 or 4, hypoxic ischemic encephalopathy, neonatal enterocolitis, bronchopulmonary dysplasia, confirmed sepsis, hypotension requiring treatment within 30 minutes of birth, intubation or cardiac intervention within the first 30 minutes, respiratory distress syndrome, mechanical ventilation for >7 days, and a 5-minute Apgar score <4.
For covariable adjustment of maternal and neonatal composite outcomes, logistic regression was used to calculate quintile–based propensity scores. This method was used to reduce selection bias, which might occur in patients who underwent prelabor cesarean delivery because their provider felt they were less likely to have a successful vaginal delivery than those who had labor induction recommended. The propensity score was used to construct groups with similar risk profiles. The backward elimination procedure (with 0.05 significance level for variable removal) was used to build a parsimonious model for calculating propensity scores. The covariates that were included initially were gestational age (240–286 vs 290–<330 weeks), maternal age, maternal race and ethnicity, parity, insurance status, maternal body mass index (BMI) at delivery, smoking during pregnancy, diabetes mellitus, fetal sex (for neonatal outcomes), steroid administration (for neonatal outcomes), small for gestational age (SGA) defined as weight of <10th percentile per methods of Alexander et al,13 and oligohydramnios defined as an amniotic fluid index of <5 cm or a greatest vertical pocket of <2 cm. After the backward elimination, gestational age, maternal age, insurance status, SGA, and oligohydramnios remained in the model. Further analyses were conducted stratified by gestational age 240–286 and 290–<330 weeks’ gestation, because this has been shown in previous literature to modify the rate of vaginal delivery. The propensity score approach was also used, however the gestational age was not included because it was used for stratification.
Secondary outcomes included a descriptive analysis of the duration of labor induction, which was defined as the duration from the start of cervical ripening or pitocin augmentation to vaginal or cesarean delivery. In patients who underwent IOL, the frequency of successful vaginal delivery was also assessed. Median and interquartile ranges (IQRs) were calculated for the duration of IOL. The proportion of vaginal deliveries after induction and the length of IOL until cesarean or vaginal delivery were analyzed by logistic regression and Cox proportional hazard regression, respectively. For both regression analyses, the covariates that were analyzed were gestational age (29–<33 vs 24–28 weeks), maternal age, maternal race and ethnicity, parity, insurance status, maternal BMI at delivery, smoking during pregnancy, diabetes mellitus, fetal sex, steroid administration, SGA, and oligohydramnios. SAS 9.4 (SAS Institute Inc, Cary, NC) was used for the analyses. All tests were 2-tailed, and P<.05 was used to define statistical significance. No imputation for missing data was performed.
Results
Of the 115,502 patients in the parent study, 471 met inclusion criteria for this analysis, of whom 200 (42%) underwent prelabor cesarean delivery and 271 (58%) underwent IOL (Figure). Patients who underwent IOL were less likely to have private insurance, prior cesarean, an SGA fetus, or oligohydramnios, but were younger and more likely to smoke (Table 1). Induction methods included oxytocin and Foley balloon (with or without additional cervical ripening), 69.1%; pharmacologic ripening and oxytocin, 18.1%; Foley balloon alone, 3.9%; and pharmacologic cervical ripening alone 8.8%. All analyses were done with intention to treat rather than delivery outcome to account for morbidity with failed IOL.
FIGURE. CONSORT flow: Patients delivered at <33 weeks’ for hypertensive disorders of pregnancy.
CONSORT, Consolidated Standards of Reporting Trials.
Bushman. Outcomes of induction vs prelabor cesarean delivery at <33 weeks for hypertensive disorders of pregnancy. Am J Obstet Gynecol MFM 2023.
TABLE 1.
Demographics of patients who underwent induction of labor vs prelabor cesarean delivery for treatment of hypertensive disorders of pregnancy at <330 weeks’ gestation
| Characteristics | IOL (N=271) | Prelabor cesarean delivery (N=200) | P value |
|---|---|---|---|
| Maternal age | 26.0±6.2 | 27.9±6.2 | <.01 |
| Maternal race | |||
| Non-Hispanic White | 112 (41.3) | 80 (40.0) | |
| Non-Hispanic Black | 103 (38.0) | 72 (36.0) | |
| Hispanic | 39 (14.4) | 29 (14.5) | |
| Other | 17 (6.3) | 19 (9.5) | .63 |
| Nulliparous | 165 (60.9) | 113 (56.5) | .34 |
| Private insurance | 88 (33.1) | 102 (51.0) | <.01 |
| Maternal BMI at delivery (kg/m2) | 33.5±8.1 | 32.7±7.8 | .15 |
| Smoking | 50 (18.5) | 22 (11.0) | .03 |
| Diabetes mellitus | 35 (12.9) | 22 (11.0) | .53 |
| Previous cesarean delivery | 5 (1.9) | 53 (26.5) | <.01 |
| Female infant | 140 (51.7) | 96 (48.0) | .43 |
| Steroid administration | 243 (89.7) | 183 (91.5) | .50 |
| Small for gestational age | 51 (18.8) | 53 (26.5) | .04 |
| Oligohydramnios | 12 (4.4) | 19 (9.5) | .03 |
| Type of PIH | .01 | ||
| gHTN | 5 (1.9) | 5 (2.5) | |
| Pre-E without severe features | 11 (4.1) | 6 (3.0) | |
| Uncategorized Pre-E | 15 (5.5) | 4 (2.0) | |
| Pre-E with severe features | 211 (77.9) | 142 (71.0) | |
| HELLP | 26 (9.6) | 36 (18.0) | |
| Eclampsia | 3 (1.1) | 7 (3.5) | |
| GA at diagnosis of PIH | 29.6±2.5 | 29.0±2.3 | <.01 |
Data are presented as number (percentage) or mean±standard deviation unless otherwise specified.
BMI, body mass index; GA, gestational age; gHTN, gestational hypertension, HELLP, hemolysis, elevated liver enzymes, low platelet count disorders; IOL, induction of labor; PIH, pregnancy-induced hypertension; Pre-E, preeclampsia.
The maternal composite outcome occurred in 10.2% of the IOL group vs 21.1% of the prelabor cesarean delivery group. This significantly lower frequency of the maternal composite outcome (unadjusted OR, 0.42; 95% confidence interval [CI], 0.25–0.72) remained significant after the propensity score adjustment (adjusted OR [aOR], 0.44; 95% CI, 0.26–0.76). The most frequent outcomes in the maternal composite were blood transfusions and ICU admissions (Table 2). After using the propensity score, the IOL group had significantly lower odds for ICU admission (3.3% vs 8.5%; aOR, 0.34 (0.15–0.82)). When running this same analysis in only patients who met the criteria for preeclampsia with severe features who underwent IOL vs prelabor cesarean delivery, no significant changes in maternal composite outcomes were found.
TABLE 2.
Composite components for maternal and neonatal morbidity in patients who underwent delivery for hypertensive disorders of pregnancy at <330 weeks by induction of labor vs prelabor cesarean delivery
| Components | IOL | Cesarean delivery | aOR (95% CI) |
|---|---|---|---|
| Maternal composite components | 10.2% | 21.1% | 0.44 (0.26–0.76) |
| Maternal death | 0 | 0 | NA |
| Hysterectomy | 0 | 0 | NA |
| Sepsis | 0 | 0 | NA |
| VTE | 0 | 0 | NA |
| ICU admission | 9 (3.3) | 17 (8.5) | 0.34 (0.15–0.82) |
| Surgery | 5 (1.9) | 4 (2.0) | NA |
| Stroke | 0 | 2 (1.0) | NA |
| Pulmonary edema | 10 (3.7) | 6 (3.0) | 1.38 (0.48–3.98) |
| DIC | 2 (0.7) | 1 (0.5) | NA |
| Blood transfusion | 12 (4.4) | 19 (9.5) | 0.47 (0.21–1.01) |
| Blood loss >1500 cc | 0 | 5 (2.5) | NA |
| Endometritis | 3 (1.1) | 3 (1.5) | NA |
| Wound infection | 2 (0.7) | 1 (0.5) | NA |
| Wound reopening | 3 (1.1) | 2 (1.0) | NA |
| Neonatal composite components | 51.9% | 63.8% | 0.71 (0.48–1.06) |
| Neonatal death | 3 (1.3) | 3 (1.7) | NA |
| Intrapartum stillbirth | 2 (0.7) | 0 | NA |
| Subgaleal hemorrhage | 0 | 0 | NA |
| Intraventricular hemorrhage grade 3 or 4 | 8 (3.0) | 10 (5.0) | 0.45 (0.16–1.26) |
| Hypoxic ischemic encephalopathy | 28 (11.1) | 17 (8.7) | 1.52 (0.79–2.94) |
| Neonatal enterocolitis | 12 (4.4) | 14 (7.0) | 0.86 (0.38–1.95) |
| BPD | 21 (7.8) | 24 (12.0) | 0.95 (0.50–1.81) |
| Confirmed sepsis | 26 (9.6) | 26 (13.0) | 0.87 (0.48–1.59) |
| Hypotension requiring treatment within 30 min | 6 (2.2) | 7 (3.5) | 0.87 (0.28–2.74) |
| Intubation or cardiac intervention within 30 min | 47 (17.3) | 65 (32.5) | 0.55 (0.35–0.87) |
| Respiratory distress syndrome | 79 (29.2) | 82 (41.0) | 0.67 (0.45–1.00) |
| Mechanical ventilation for >7 d | 20 (7.4) | 30 (15.0) | 0.66 (0.36–1.23) |
| 5-min Apgar <4 | 12 (4.4) | 6 (3.0) | 2.38 (0.85–6.66) |
Data are presented as number (percentage) or mean±standard deviation, unless otherwise specified for adjustments.
aOR, adjusted odds ratio, BPD, bronchopulmonary dysplasia; CI, confidence interval; ICU, intensive care unit; IOL, induction of labor; NA, not applicable owing to small numbers (n<6).
Neonatal composite morbidity rates were significantly lower in unadjusted analysis in patients undergoing IOL (51.9% vs 63.8%, unadjusted OR, 0.61; 95% CI, 0.42–0.89). (Table 3). However, after adjustment with the propensity score, the association was no longer significant (aOR, 0.71; 95% CI, 0.48–1.06) (Table 3). When running this analysis in only patients being delivered for preeclampsia with severe features, there was no significant change in neonatal composite outcomes. The most common outcomes in the neonatal composite were respiratory distress syndrome and intubation or cardiac intervention within 30 minutes. After multivariable adjustment, neonates in the IOL group had significantly fewer intubations or cardiac interventions within 30 minutes (17.3% vs 32.5%, aOR, 0.55; 95% CI, 0.35–0.87). There were 2 intrapartum stillbirths in the IOL group, and none in the prelabor cesarean delivery group (Table 2).
TABLE 3.
Maternal and neonatal morbidity composite score by 240–286 and 290–<330 weeks in hypertensive disorders of pregnancy by induction of labor vs prelabor cesarean delivery
| Weeks GA | Maternal composite | |||
|---|---|---|---|---|
| IOL | Cesarean delivery | OR (95% CI) | aOR (95% CI) | |
| 240–<330 | 10.2% | 21.1% | 0.42 (0.25–0.72) | 0.44 (0.26–0.76) |
| 240–<286 | 17.9% | 22.2% | 0.76 (0.31–1.88) | 0.79 (0.31–1.97) |
| 290–<330 | 8.1% | 20.6% | 0.34 (0.18–0.65) | 0.33 (0.17–0.65) |
| Neonatal composite | ||||
| GA (wk) | IOL | Cesarean delivery | OR (95% CI) | aOR (95% CI) |
| 240–<330 | 51.9% | 63.8% | 0.61 (0.42–0.89) | 0.71 (0.48–1.06) |
| 240–<286 | 85.7% | 87.5% | 0.86 (0.30–2.46) | 0.90 (0.31–2.61) |
| 290–<330 | 42.8% | 52.6% | 0.67 (0.44–1.04) | 0.67 (0.42–1.06) |
aOR, adjusted odds ratio; CI, confidence interval; GA, gestational age; IOL, induction of labor; OR, odds ratio.
Of the 271 patients who underwent IOL, 143 (52.8%) delivered vaginally (Table 4). The primary indications for cesarean delivery following IOL were nonreassuring fetal status (61.7%), dystocia or failed induction (24.2%), and “other” (14.1%). Vaginal delivery rates after labor induction were 39.3% at 240–286 weeks gestational age and 56.3% at 290–<33 weeks’ gestation. Patients who were parous were more likely to have an IOL resulting in vaginal delivery. Patients who were obese, of advanced maternal age, had private insurance, or had an SGA fetus were less likely to achieve a vaginal delivery (Table 5).
TABLE 4.
Delivery outcomes in patients who underwent induction of labor <330 weeks for hypertensive disorders of pregnancy
| GA | Vaginal delivery % (95% CI) | Length of IOL (h)a |
|---|---|---|
| 240–<330 wk | 52.8 (46.8–58.7) | 13.9 (8.7–22.2) |
| 240–286 wk | 39.3 (26.5–52.1) | 15.2 (8.7–23.4) |
| 290–<330 wk | 56.3 (49.7–62.9) | 13.3 (8.6–22.0) |
CI, confidence interval; GA, gestational age; IOL, induction of labor.
Median (interquartile range).
TABLE 5.
Characteristics associated with vaginal delivery and duration of labor follow induction of labor for hypertensive disorders of pregnancy at <330 weeks gestation
| Characteristics associated with vaginal delivery | |
|---|---|
| aOR (95% CI) | |
| Parous | 4.88 (2.46–9.71) |
| Small for gestational age | 0.33 (0.16–0.69) |
| Maternal BMI at delivery | 0.96 (0.93–0.997) |
| 24–28 wk | 0.36 (0.18–0.70) |
| Private insurance | 0.46 (0.23–0.92) |
| Maternal age | 0.94 (0.89–0.99) |
| Characteristics associated with duration of labor | |
| aOR (95% CI) | |
| African American | 1.43 (1.07–1.92) |
| Maternal BMI at delivery | 0.98 (0.96–0.99) |
aOR, adjusted odds ratio; BMI, body mass index; CI, confidence interval.
The median duration of IOL before a vaginal or cesarean delivery was 13.9 (IQR, 8.7–22.2) hours (Table 4). In patients who were 240–286 and 290–<330 weeks’ gestation, the median durations of labor were 15.2 and 13.3 hours, respectively. Maternal BMI at delivery was associated with a longer IOL, whereas patients who were African American had shorter labors (Table 5).
Discussion
Principal findings
As seen in previous studies, maternal morbidity composite scores were lower in patients with hypertensive disorders of pregnancy who required delivery at <33 weeks and underwent IOL as opposed to those who underwent prelabor cesarean delivery.9,14 IOL however was not associated with lower neonatal morbidity. Over half of patients who underwent an IOL achieved a vaginal delivery, with a median duration of labor of 13.9 hours. The likelihood of successful vaginal delivery increased with increasing gestational ages, although 39% of patients still delivered vaginally between 240 and 286 weeks gestation. We also identified factors associated with the success and duration of induction, which included both maternal (previous vaginal delivery, age, insurance status, obesity, and race) and neonatal (SGA) characteristics.
Results
Previous studies have shown a 45% to 67% vaginal delivery rate after IOL in patients with severe preeclampsia, which is consistent with our findings.5,10,15,16 Our finding of a 39% vaginal delivery rate in early preterm patients at 240–286 weeks’ gestation is also consistent with previous findings.5,6 Three studies and 1 systematic review that evaluated neonatal outcomes found them to be similar regardless of delivery approach.4,5,15 The majority of studies that assessed maternal outcomes according to delivery approach in patients with preeclampsia included patients at all gestational ages, whereas our study focused on patients <33 weeks. There is 1 systematic review and 1 retrospective analysis that showed no difference in maternal outcomes associated with mode of delivery.4 Previous studies also included patients with nonreassuring fetal heart rate tracings before the decision to deliver, even though such patients are not candidates for labor induction.10,17 Many previous studies have compared mode of delivery, cesarean delivery vs vaginal delivery; instead of the approach to delivery, IOL vs prelabor cesarean delivery. However, there is 1 large retrospective cohort which compared intended mode of delivery in patients <33 weeks’ gestation being delivery for preeclampsia which show similar outcomes.9
Clinical implications
There is a paucity of data addressing length of labor following induction given the wide variation of labor induction methods and practices. However, we do not feel our IOL time, of 13.9 hours with a range of 8.7 to 22.2 hours, was possibly significantly prolonged despite prematurity, given that in studies by Zhang et al18 term laboring patients who present at 4 cm have labor times ranging from 4.1 to 17.8 hours. Although IOL in the setting of prematurity is somewhat prolonged, providers should be reassured that the majority (52.8%) will have a successful vaginal delivery following IOL; and patients should be allowed more time in labor, in the setting of hypertensive disorders of pregnancy and IOL, and given maternal benefit without an apparent increase in neonatal complications.
It is unclear why more patients with private insurance underwent prelabor cesarean delivery. This finding could be a result of confounding because more patients with private insurance also had a history of previous cesarean delivery. The increased rate of prelabor cesarean delivery is likely secondary to a history of previous cesarean delivery rather than socioeconomic factors leading patients without private insurance to choose IOL. Further studies need to be conducted evaluating delivery preferences based on insurance status to evaluate this finding more definitively.
Research implications
The majority of patients requiring early preterm delivery for hypertensive disorders of pregnancy who undergo IOL will have a vaginal delivery as well as a significantly lower rate of maternal morbidity regardless of delivery outcome. No difference in neonatal morbidity was seen by intended mode of delivery. These findings should provide useful information in terms of counseling and decision making in patients requiring early preterm delivery for treatment of hypertensive disorders of pregnancy. Given that this is a retrospective study, additional research would be beneficial to more definitively define outcomes.
Strengths and limitations
Our study has several strengths, including the fact that the data used were obtained prospectively by trained chart abstractors, we analyzed a large population of patients with hypertensive disorders of pregnancy requiring early preterm delivery, and we compared maternal and neonatal outcomes–based intention-to-treat (actual clinical management). We used propensity scores to reduce confounding.6
Although propensity scoring did reduce the risk of confounding, after propensity score matching our population was diminished, making evaluation of specific, rare maternal and neonatal outcomes not possible, and limiting the ability of this study to assess these important morbidities. We do acknowledge the potential for selection bias and confounding by unknown factors owing to lack of randomization of the interventions and limitation of propensity matching. We acknowledge that women who underwent prelabor cesarean delivery in theory are more likely to have pregnancies complicated by fetal growth restriction, nonreassuring fetal heart tones or other contraindications to IOL. However, we feel that these limitations do not dilute the findings that in pregnancies affected by hypertensive disorders of pregnancy requiring delivery at <33 weeks’, without relative contraindications to IOL, the majority of these women undergo successful IOL and therefore the diagnosis of hypertensive disorders of pregnancy at <33 weeks alone should not be a contraindication to IOL. Therefore, these findings should be interpreted as supportive rather than conclusive prompting further studies. Nevertheless, a randomized trial addressing this question does not currently exist and would greatly add to the literature. One confounding factor may be our inability to adjust for severity of disease, however we did try to mitigate this factor by addressing only deliveries at <330 weeks’ gestation because delivery at this gestational age should only be for severe disease. Considering that the data set used in this secondary analysis are now dated, we are unable to account for advancement in neonatal ICU management and changes in clinical definitions or care; however, given that our comparison groups are from the same era, our findings are felt to hold continued significance. Further studies to evaluate neonatal and maternal outcomes based on Bishop score would be of interest.
Conclusions
Among patients delivered for hypertensive disorders of pregnancy at <330 weeks, labor induction compared with prelabor cesarean delivery, is associated with significantly lower odds of maternal but not neonatal morbidity. More than half of patients who were induced, delivered vaginally with a median duration of labor induction of 13.9 hours. ■
AJOG MFM at a Glance.
Why was this study conducted?
This study was conducted to identify potential effects of mode of delivery on maternal and neonatal outcomes in women undergoing delivery for hypertensive disorders in pregnancy at <33 weeks.
Key findings
Among patients delivered for hypertensive disorders of pregnancy <330 weeks, labor induction compared with prelabor cesarean delivery, is associated with significantly lower odds of maternal but not neonatal morbidity. More than half of patients induced delivered vaginally, with a median duration of labor induction of 13.9 hours.
What does this add to what is known?
Our analysis showed that induction of labor for hypertensive disorders in pregnancy at <33 weeks was not associated with lower neonatal morbidity and that over half of patients who underwent an induction of labor achieved a vaginal delivery.
ACKNOWLEDGMENTS
The authors thank Alan T.N. Tita, MD, PhD for assistance with secondary concept design and manuscript development; Sarah Anderson for assistance on manuscript development; and Elizabeth Thom, PhD; Madeline M. Rice, PhD; Brian M. Mercer, MD and Catherine Y. Spong, MD for protocol development and oversight.
The project described was supported by grants from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) [HD21410, HD27869, HD27915, HD27917, HD34116, HD34208, U10 HD36801, HD40500, HD40512, HD40544, HD40545, HD40560, HD40485, HD53097, HD53118] and the National Center for Research Resources [UL1 RR024989; 5UL1 RR025764]. The comments and views of the authors do not necessarily represent views of the National Institutes of Health.
Footnotes
The authors report no conflict of interest.
Contributor Information
Elisa T. Bushman, The University of Alabama at Birmingham, Birmingham, AL.
William A. Grobman, Northwestern University, Chicago, IL.
Jennifer L. Bailit, MetroHealth Medical Center-Case Western Reserve University, Cleveland, OH.
Uma M. Reddy, Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, MD.
Ronald J. Wapner, Columbia University, New York, NY.
Michael W. Varner, University of Utah Health Sciences Center, Salt Lake City, UT.
John M. Thorp, Jr, The University of North Carolina at Chapel Hill, Chapel Hill, NC.
Steve N. Caritis, University of Pittsburgh, Pittsburgh, PA.
Mona Prasad, The Ohio State University, Columbus, OH.
George R. Saade, The University of Texas Medical Branch, Galveston, TX.
Yoram Sorokin, Wayne State University, Detroit, MI.
Dwight J. Rouse, Brown University, Providence, RI.
Sean C. Blackwell, The University of Texas Health Science Center at Houston-Children’s Memorial Hermann Hospital, Houston, TX.
Jorge E. Tolosa, Oregon Health & Science University, Portland, OR.
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