Background
The safest mode of delivery to use for very preterm infants is an ongoing topic of debate. There are many reasons to perform a cesarean delivery in cases of extremely preterm and very preterm infants, including indication for labor, fetal distress, maternal indications, and malpresentation.
Objective
This study aimed to determine whether cesarean delivery is associated with a considerable improvement in neonatal morbidity.
Study Design
This study is a retrospective cohort study of all singleton pregnancies, delivered from 22 to 29 weeks’ gestation between 2010 and 2015, admitted for preterm labor or preterm premature rupture of membranes and excluded neonates with a delivery weight ≤500 g, multiple gestations, cases with intrauterine fetal demise, and induced terminations. The primary outcome for the study was a neonatal morbidity composite (Apgar score of <5 at 5 minutes, prolonged ventilation (>28 days), intraventricular hemorrhage, necrotizing enterocolitis, coagulopathy, discharged on home ventilator support, or discharged with enteric feeding tube). Cesarean deliveries were performed for standard obstetrical indications. Regression models were used and adjusted for nulliparity, delivery year, and presentation at the time of delivery to determine whether cesarean delivery is associated with neonatal morbidity or neonatal death.
Results
There were 271 eligible deliveries, which included 128 cesarean deliveries and 143 vaginal deliveries. The cesarean delivery group had fewer nulliparous patients and more fetuses presenting in breech position at the time of delivery. The overall composite neonatal morbidity occurred in 202 of the 271 (74.5%) deliveries and mortality occurred in 26 of the 271 (9.59%) deliveries. When adjusting for nulliparity, delivery year, and fetal presentation at the time of delivery, cesarean delivery was associated with a decreased risk for death in the delivery room or within 24 hours after delivery (adjusted risk ratio, 0.18; 95% confidence interval, 0.05–0.63; P =.03). Cesarean delivery was associated with an increased use of exogenous surfactant (adjusted risk ratio, 1.20; 95% confidence interval, 1.05–1.38; P =.01) and bag mask ventilation (adjusted risk ratio, 1.17; 95% confidence interval, 1.01–1.37; P =.03). In a secondary analysis that included only patients who received a complete course of steroids, there were no differences in the composite morbidity or mortality.
Conclusion
Cesarean delivery performed for standard obstetrical indications in cases of very preterm neonates is associated with a decreased risk for death in the delivery room or within 24 hours of delivery but is not associated with an improvement in the overall morbidity or mortality.
Introduction
The safest mode of delivery to use for very preterm infants (24–29 weeks’ gestation) and extremely preterm infants (22–24 weeks’ gestation) is an ongoing topic of debate. There are many reasons to perform a cesarean delivery (CD) in cases of extremely preterm and very preterm infants, including indication for labor, fetal distress, maternal indications, and malpresentation. A 2018 study did not find a difference in neonatal morbidity or mortality among preterm infants who presented in breech position during labor and who were delivered vaginally before 28 weeks’ gestation. However, a 2019 study demonstrated that performing a CD for very preterm infants presenting in breech position is associated with improved morbidity and mortality.
Why was this study conducted?
This study aimed to determine whether the mode of delivery in cases of very preterm neonates is associated with a decreased risk for morbidity or mortality.
Key findings
There is no difference in composite neonatal morbidity or mortality on the basis of the mode of delivery but there is an associated increase in immediate survival among neonates delivered by cesarean delivery.
What does this add to what is known?
Cesarean delivery performed for standard obstetrical indications is not associated with improved outcomes in very preterm neonates but with an increased likelihood of a live birth.
There is an ongoing debate about the safest mode of delivery for very preterm infants given the mixed results regarding improvements in the outcomes and maternal risks. There is a marked risk of bleeding at the time of delivery and risk for certain hysterotomies, such as classical incision, in subsequent pregnancies. , In cases with extremely preterm infants (22 to 23+6 weeks’ gestation), there is an even greater debate about the mode of delivery and whether it confers a benefit to the fetus. It has been reported that immediate survival is improved with CD but it does not impact the major morbidities associated with prematurity. A 2016 study found that CD was associated with an improvement in the condition of the infant at birth and lower delivery room deaths but it did not contribute to the long-term survival of extremely preterm infants. However, a 2015 study found that there was no difference in neurodevelopmental scoring based on the mode of delivery in extremely preterm infants.
The morbidity and mortality of extremely preterm and very preterm infants has changed drastically over time with the advent of newer neonatal technologies. This has led to earlier viable gestational ages (GA), most recently including 22-week-old fetuses. This study aimed to determine whether CD is independently associated with improved preterm neonatal morbidity or mortality in early preterm patients. We hypothesized that CD is not associated with improved neonatal morbidity or mortality in very preterm neonates (22–29 weeks’ gestation).
Materials and Methods
This was a retrospective cohort study of all women who delivered because of preterm labor (PTL) or preterm premature rupture of membranes (PPROM) between 22+0 and 29+0 weeks’ gestation in the period from 2010 to 2015 at the Barnes-Jewish Hospital in St. Louis, Missouri. Patients who delivered between 22+0 and 29+0 weeks’ gestation were identified through review of the electronic medical record system and delivery logs. The Washington University School of Medicine Human Research Protection Office and the Washington University Institutional Review Board approved this study. Chart abstraction from the Research Electronic Data Capture system was performed using a chart abstraction form. The primary author performed 65% of the chart abstractions and trained medical students performed the remaining 35% of the abstractions. The charts abstracted by medical students were reviewed and validated by the primary author.
Patients were included in the study cohort if they were admitted between 22+0 and 29+0 weeks’ gestation with a singleton pregnancy and an admission diagnosis of PTL or PPROM. Exclusion criteria included an admission diagnosis other than PTL or PPROM, a multiple gestation, intrauterine fetal demise, fetal anomalies, birthweight of ≤500 g at delivery, and induced terminations. We included women regardless of presentation of the fetus, because abnormal presentation is a common occurrence in preterm deliveries and an indication for delivery by CD. We included all qualifying pregnancies delivered during the time period even if the same woman was included more than once during the study period.
The primary outcome for the study was a neonatal morbidity composite. The composite included Apgar score <5 at 5 minutes, prolonged ventilation (defined as ventilation for >28 days), intraventricular hemorrhage, necrotizing enterocolitis, coagulopathy, bronchopulmonary dysplasia, discharged home on ventilator support, or discharged with enteric feeding tube. These diagnoses were extracted from the neonatal charts and only confirmed when documented by the neonatology physician. The Apgar score at 5 minutes was assigned by the neonatal resuscitation team in the delivery room and recorded in the delivery record. The secondary outcomes included neonatal death in the delivery room or within 24 hours and death within 28 days of delivery.
Maternal data collected included demographic information such as age at time of delivery, parity, ethnicity, and history of preterm birth. Obstetrical data collected included GA at delivery, estimated fetal weight (EFW) in grams based on admission ultrasound, birthweight in grams, whether a full or partial course of antenatal steroids was given before delivery, presentation of the fetus at the time of delivery (vertex or breech), and whether magnesium for neuroprotection was given before delivery. We utilized the estimated due dates that were recorded for all patients based on the earliest ultrasound performed during pregnancy.
The local standard of practice is to reserve CD for standard obstetrical indications. The indications for delivery collected included nonreassuring fetal heart tones (as defined in the chart by the delivering obstetrician), malpresentation, oligohydramnios, PPROM, and nonreassuring antenatal testing (either nonstress test or biophysical profile). If the indication for delivery was not clear or not documented, no indication was listed. During the study time frame, the practice pattern at this institution was to only offer resuscitation to fetuses ≥24 weeks’ gestation. In addition, for all patients presenting from 22 to 24 weeks’ gestation, joint periviability counseling is provided by the obstetrical care and neonatology teams. Neonatal data collected included initial resuscitation by the neonatology team, which included bag mask ventilation and continuous positive airway pressure, intubation within 5 minutes in the delivery room, chest compressions, and whether an exogenous surfactant was given.
Regression models were used to test the association between CD and adverse neonatal outcomes. The logistic regression analysis adjusted for presentation at the time of delivery, delivery year, and nulliparity. We chose potential confounders that could have an effect on both the exposure and outcome. We included the year of delivery to adjust for temporal changes in resuscitation attempts. A secondary analysis was performed and included only those neonates who received a full course of antenatal steroids before delivery. Stata version 16.1 (StataCorp LLC, College Station, TX) was used to perform all analyses. Statistical significance was set at a P value of <.05.
Results
There were 271 eligible deliveries in the cohort, of which 128 were CDs (47.2%) and 143 (52.8%) were vaginal deliveries. Malpresentation was the most common indication for CD (56 of 128; 43.75%). The CD cohort had fewer nulliparous patients and more fetuses presenting in breech position at the time of delivery ( Table 1 ).
| Demographics | Vaginal delivery (n=143), n (%) | Cesarean delivery (n=128), n (%) | P value |
|---|---|---|---|
| Maternal age (y) | |||
| <35 | 132 (92.31) | 106 (84.80) | |
| 35–40 | 8 (5.59) | 18 (14.4) | |
| >41 | 3 (2.10) | 1 (0.80) | .30 |
| Ethnicity | |||
| African American | 86 (60.14) | 74 (58.73) | |
| White | 53 (37.06) | 42 (33.33) | |
| Hispanic or Asian or other or unknown | 4 (2.80) | 10 (7.85) | .28 |
| Nulliparous | |||
| Yes | 71 (49.65) | 40 (31.25) | <.01 |
| Previous preterm birth | |||
| Multiparous, no previous preterm birth | 38 (54.29) | 43 (51.19) | |
| Multiparous, previous preterm birth | 32 (45.71) | 41 (48.81) | .75 |
| Delivery year | |||
| 2010 | 19 (13.29) | 11 (8.59) | |
| 2011 | 23 (16.08) | 25 (19.53) | |
| 2012 | 26 (18.18) | 24 (18.75) | |
| 2013 | 23 (16.08) | 20 (15.62) | |
| 2014 | 32 (22.38) | 24 (15.62) | |
| 2015 | 20 (13.99) | 24 (18.75) | .68 |
| Gestational age at delivery (wk) | |||
| 22.0–23.6 | 17 (11.89) | 12 (9.38) | |
| 24.0–26.6 | 53 (37.06) | 70 (54.69) | |
| 27.0–29.0 | 73 (51.05) | 46 (35.94) | .01 |
| Fetal sex | |||
| Male | 83 (58.04) | 75 (58.59) | |
| Female | 60 (41.96) | 53 (41.41) | .93 |
| EFW based on US (g) | |||
| 500–1000 | 72 (50.4) | 70 (57.9) | .27 |
| Weight at delivery (g) | |||
| 500–1000 | 71 (49.7) | 77 (60.2) | .08 |
| Antenatal steroid course | |||
| Partial | 40 (45.98) | 35 (46.67) | .55 |
| Complete | 70 (56.00) | 75 (66.96) | .08 |
| Magnesium for neuroprotection | |||
| Yes | 110 (79.71) | 104 (82.54) | .56 |
| Presentation at the time of delivery | |||
| Vertex | 127 (92.03) | 29 (25.44) | |
| Breech | 11 (7.97) | 85 (74.56) | <.01 |
| Indication for delivery | |||
| No indication listed | 135 (94.41) | 10 (7.81) | |
| NRFHT | 2 (1.40) | 28 (21.88) | |
| Malpresentation | 0 | 56 (43.75) | |
| Oligohydramnios | 0 | 1 (0.78) | |
| PPROM | 6 (4.20) | 5 (3.91) | |
| Nonreassuring antenatal testing | 0 | 5 (3.91) | <.01 |
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