doi:10.1111/jog.12689
J. Obstet. Gynaecol. Res. Vol. 41, No. 8: 1193–1200, August 2015
Premature rupture of membranes and neonatal respiratory morbidity at 32–41 weeks’ gestation: A retrospective singlecenter cohort study Tomoyuki Shimokaze1, Kazuhiro Akaba1, Michio Banzai2, Kaori Kihara2, Emi Saito1 and Hiroshi Kanasugi2 1
Departments of Pediatrics, Saiseikai Yamagata Hospital, Yamagata, Japan 2Departments of Obstetrics and Gynecology, Saiseikai Yamagata Hospital, Yamagata, Japan
Abstract Aim: To ascertain whether premature rupture of membranes (PROM) independently affects the risk of neonatal respiratory morbidity at 32–41 weeks’ gestation because previous reports have given insufficient consideration to the mode of delivery and labor onset. Methods: Data on 4,629 consecutive singleton infants were retrospectively collected. Respiratory morbidity was limited to respiratory distress syndrome and transient tachypnea of the newborn, both of which are related to prematurity. Delivery modes were divided into four groups based on the existence of PROM and of labor onset, and the respiratory morbidity was examined according to the number of weeks of gestational age. Multivariate analysis including PROM and delivery mode was conducted to examine the association of respiratory morbidity. Results: Respiratory morbidity or a positive pressure requirement delivered after PROM and intact amniochorionic membranes accompanied by labor were similar at all weeks. Around 37 weeks, the absence of labor onset was associated with a risk of respiratory morbidity or positive pressure requirement. Significant respiratory risk was not associated with the incidence of PROM (adjusted odds ratio [aOR], 0.98; 95% confidence interval [CI], 0.52–1.83), interval from rupture to delivery (aOR, 1.00; 95% CI, 0.99–1.01), clinical chorioamnionitis, induction management, pregnancy-related complications, or neonatal sex. Delivery by Cesarean section and early gestational age presented a significant risk for respiratory morbidity. Conclusions: Neither PROM nor latency after PROM at 32–41 weeks affected neonatal respiratory morbidity. Avoiding Cesarean section instead of simply increasing the time to delivery may help to reduce respiratory morbidity. Key words: 2.711 cesarean section, 2.523 premature rupture of membrance, 2.800 neonatology, 2.715 labor management/labor induction and augmentation, 2.900 placental pathology.
Introduction Standard management of the premature rupture of membranes (PROM) at 24–31 weeks’ gestational age (GA) is expectant. Labor induction is recommended if lung maturation is confirmed at 32–33 weeks’ GA.
After 33 weeks’ GA, it is generally recommended to proceed to delivery (usually by induction) because of the decreased likelihood of respiratory complications.1 Accurate estimation of the risk of neonatal respiratory morbidity is important for effective management of PROM.
Received: August 11 2014. Accepted: January 4 2015. Reprint request to: Tomoyuki Shimokaze, Departments of Pediatrics, Saiseikai Yamagata Hospital, 79-1 Okimachi, Yamagata 990-8545, Japan. Email: [email protected]
© 2015 The Authors Journal of Obstetrics and Gynaecology Research © 2015 Japan Society of Obstetrics and Gynecology
1193
T. Shimokaze et al.
Among cases of PROM, reports of neonatal respiratory morbidity early in life describe no constant increase, decrease, or immutability. The causes of PROM are multifactorial, and no effective intervention for their prevention has been identified.2,3 Differences in the circumstances associated with PROM (i.e,, GA, mode of delivery, interval from membrane rupture to delivery, and the presence of chorioamnionitis [CAM]) are presumed to be factors related to respiratory morbidity. However, elective Cesarean section (CS) is associated with a greater risk of neonatal respiratory morbidity than is vaginal delivery (VD), even at >37 weeks.4–8 Furthermore, the risk of respiratory morbidity from CS accompanied by labor is also higher than in spontaneous VD because labor and passage through the birth canal protect against respiratory complications.6,7 In earlier reports describing the relationship between neonatal respiratory morbidity and PROM, the mode of delivery and labor onset, which have strong effects on lung maturation, were insufficiently considered. This retrospective single-center cohort study examined the influence of PROM on neonatal respiratory morbidity from 32 to 41 weeks’ GA.
Methods Neonatal and maternal data were obtained from a database comprising maternal and neonatal records from the medical charts of patients admitted to Yamagata Saisei Hospital (tertiary care perinatal facility) from January 2007 to October 2013. This study was approved by the institutional review board (Number 159, April 5, 2013). Labor was defined as cervical change and painful contractions occurring more frequently than once every 10 min, as confirmed subjectively or using cardiotocography. We examined the following data: maternal information, including maternal age, gravidity, parity, GA at delivery, mode of delivery, induction delivery, and corticosteroid administration in the perinatal period; pregnancy-related complications, including pregnancyinduced hypertension (PIH), diabetes, and threatened preterm delivery; clinical CAM; and PROM. GA was determined based on the first day of the menstrual period and the first-trimester ultrasound. The modes of delivery were divided into four groups: unassisted VD, VD assisted by vacuum extraction, CS with labor, and CS without labor. PIH, pregestational diabetes, and gestational diabetes were diagnosed by the patient’s obstetrical and physical provider. PROM was
1194
diagnosed by sterile speculum examination using a combination of vaginal pooling and nitrazine testing. Clinical CAM was defined as a maternal body temperature of >38 °C, fundal tenderness, and leukocytosis. We included singleton live infants without major congenital anomalies. Neonatal information included sex, birth weight, size for GA, Apgar score, infection, and respiratory morbidity. Small or large for GA was defined in comparison with the 10th and 90th percentiles of the infant physical development research report of the Ministry of Health, Labour and Welfare of Japan in 2001. Early-onset neonatal infection was defined as the combination of neonatal clinical signs (lethargy, poor feeding, hyperthermia, hypothermia, increased apnea, shock, and signs of localized infection), abnormal glucose homeostasis, abnormal leukocyte count, abnormal platelet count, positive Creactive protein, and culture-proven sepsis within 7 days after birth. Respiratory morbidity was defined as a requirement for oxygen or positive-pressure ventilation for >24 h attributable to respiratory distress syndrome (RDS) or transient tachypnea of the newborn (TTN). We excluded meconium aspiration syndrome and perinatal asphyxia, which are pathophysiologically different from lung maturation. Pneumonia was not included in respiratory morbidity, but was included in infection. RDS was defined as the combination of abnormal chest radiograph findings (symmetrical granular opacities in both lung fields with a superimposed air bronchogram), low stable microbubble count in gastric aspirates, and the need for surfactant replacement therapy. TTN was defined as abnormal chest radiograph findings (increased vascular markings, fluid in the horizontal fissure, and overinflation of the lung) and a high microbubble count in gastric aspirates. According to our institutional practice, PROM was expectantly managed within the first 12–24 h. If no progressive labor occurred, active management was then performed with oxytocin, prostaglandin, or both in the absence of a nonreassuring fetal status or intrauterine infection. Tocolytic therapy was administered at up to 37 weeks’ GA in the management of threatened preterm labor. All women at high risk of preterm delivery (
J. Obstet. Gynaecol. Res. Vol. 41, No. 8: 1193–1200, August 2015
Premature rupture of membranes and neonatal respiratory morbidity at 32–41 weeks’ gestation: A retrospective singlecenter cohort study Tomoyuki Shimokaze1, Kazuhiro Akaba1, Michio Banzai2, Kaori Kihara2, Emi Saito1 and Hiroshi Kanasugi2 1
Departments of Pediatrics, Saiseikai Yamagata Hospital, Yamagata, Japan 2Departments of Obstetrics and Gynecology, Saiseikai Yamagata Hospital, Yamagata, Japan
Abstract Aim: To ascertain whether premature rupture of membranes (PROM) independently affects the risk of neonatal respiratory morbidity at 32–41 weeks’ gestation because previous reports have given insufficient consideration to the mode of delivery and labor onset. Methods: Data on 4,629 consecutive singleton infants were retrospectively collected. Respiratory morbidity was limited to respiratory distress syndrome and transient tachypnea of the newborn, both of which are related to prematurity. Delivery modes were divided into four groups based on the existence of PROM and of labor onset, and the respiratory morbidity was examined according to the number of weeks of gestational age. Multivariate analysis including PROM and delivery mode was conducted to examine the association of respiratory morbidity. Results: Respiratory morbidity or a positive pressure requirement delivered after PROM and intact amniochorionic membranes accompanied by labor were similar at all weeks. Around 37 weeks, the absence of labor onset was associated with a risk of respiratory morbidity or positive pressure requirement. Significant respiratory risk was not associated with the incidence of PROM (adjusted odds ratio [aOR], 0.98; 95% confidence interval [CI], 0.52–1.83), interval from rupture to delivery (aOR, 1.00; 95% CI, 0.99–1.01), clinical chorioamnionitis, induction management, pregnancy-related complications, or neonatal sex. Delivery by Cesarean section and early gestational age presented a significant risk for respiratory morbidity. Conclusions: Neither PROM nor latency after PROM at 32–41 weeks affected neonatal respiratory morbidity. Avoiding Cesarean section instead of simply increasing the time to delivery may help to reduce respiratory morbidity. Key words: 2.711 cesarean section, 2.523 premature rupture of membrance, 2.800 neonatology, 2.715 labor management/labor induction and augmentation, 2.900 placental pathology.
Introduction Standard management of the premature rupture of membranes (PROM) at 24–31 weeks’ gestational age (GA) is expectant. Labor induction is recommended if lung maturation is confirmed at 32–33 weeks’ GA.
After 33 weeks’ GA, it is generally recommended to proceed to delivery (usually by induction) because of the decreased likelihood of respiratory complications.1 Accurate estimation of the risk of neonatal respiratory morbidity is important for effective management of PROM.
Received: August 11 2014. Accepted: January 4 2015. Reprint request to: Tomoyuki Shimokaze, Departments of Pediatrics, Saiseikai Yamagata Hospital, 79-1 Okimachi, Yamagata 990-8545, Japan. Email: [email protected]
© 2015 The Authors Journal of Obstetrics and Gynaecology Research © 2015 Japan Society of Obstetrics and Gynecology
1193
T. Shimokaze et al.
Among cases of PROM, reports of neonatal respiratory morbidity early in life describe no constant increase, decrease, or immutability. The causes of PROM are multifactorial, and no effective intervention for their prevention has been identified.2,3 Differences in the circumstances associated with PROM (i.e,, GA, mode of delivery, interval from membrane rupture to delivery, and the presence of chorioamnionitis [CAM]) are presumed to be factors related to respiratory morbidity. However, elective Cesarean section (CS) is associated with a greater risk of neonatal respiratory morbidity than is vaginal delivery (VD), even at >37 weeks.4–8 Furthermore, the risk of respiratory morbidity from CS accompanied by labor is also higher than in spontaneous VD because labor and passage through the birth canal protect against respiratory complications.6,7 In earlier reports describing the relationship between neonatal respiratory morbidity and PROM, the mode of delivery and labor onset, which have strong effects on lung maturation, were insufficiently considered. This retrospective single-center cohort study examined the influence of PROM on neonatal respiratory morbidity from 32 to 41 weeks’ GA.
Methods Neonatal and maternal data were obtained from a database comprising maternal and neonatal records from the medical charts of patients admitted to Yamagata Saisei Hospital (tertiary care perinatal facility) from January 2007 to October 2013. This study was approved by the institutional review board (Number 159, April 5, 2013). Labor was defined as cervical change and painful contractions occurring more frequently than once every 10 min, as confirmed subjectively or using cardiotocography. We examined the following data: maternal information, including maternal age, gravidity, parity, GA at delivery, mode of delivery, induction delivery, and corticosteroid administration in the perinatal period; pregnancy-related complications, including pregnancyinduced hypertension (PIH), diabetes, and threatened preterm delivery; clinical CAM; and PROM. GA was determined based on the first day of the menstrual period and the first-trimester ultrasound. The modes of delivery were divided into four groups: unassisted VD, VD assisted by vacuum extraction, CS with labor, and CS without labor. PIH, pregestational diabetes, and gestational diabetes were diagnosed by the patient’s obstetrical and physical provider. PROM was
1194
diagnosed by sterile speculum examination using a combination of vaginal pooling and nitrazine testing. Clinical CAM was defined as a maternal body temperature of >38 °C, fundal tenderness, and leukocytosis. We included singleton live infants without major congenital anomalies. Neonatal information included sex, birth weight, size for GA, Apgar score, infection, and respiratory morbidity. Small or large for GA was defined in comparison with the 10th and 90th percentiles of the infant physical development research report of the Ministry of Health, Labour and Welfare of Japan in 2001. Early-onset neonatal infection was defined as the combination of neonatal clinical signs (lethargy, poor feeding, hyperthermia, hypothermia, increased apnea, shock, and signs of localized infection), abnormal glucose homeostasis, abnormal leukocyte count, abnormal platelet count, positive Creactive protein, and culture-proven sepsis within 7 days after birth. Respiratory morbidity was defined as a requirement for oxygen or positive-pressure ventilation for >24 h attributable to respiratory distress syndrome (RDS) or transient tachypnea of the newborn (TTN). We excluded meconium aspiration syndrome and perinatal asphyxia, which are pathophysiologically different from lung maturation. Pneumonia was not included in respiratory morbidity, but was included in infection. RDS was defined as the combination of abnormal chest radiograph findings (symmetrical granular opacities in both lung fields with a superimposed air bronchogram), low stable microbubble count in gastric aspirates, and the need for surfactant replacement therapy. TTN was defined as abnormal chest radiograph findings (increased vascular markings, fluid in the horizontal fissure, and overinflation of the lung) and a high microbubble count in gastric aspirates. According to our institutional practice, PROM was expectantly managed within the first 12–24 h. If no progressive labor occurred, active management was then performed with oxytocin, prostaglandin, or both in the absence of a nonreassuring fetal status or intrauterine infection. Tocolytic therapy was administered at up to 37 weeks’ GA in the management of threatened preterm labor. All women at high risk of preterm delivery (
