The Timing of Elective Caesarean Section on Neonatal Respiratory Outcome in Hong Kong

Abstract

Objectives: To evaluate the incidence of neonatal respiratory morbidity in term infants, especially babies delivered in Hong Kong by elective Caesarean section, and to assess the influence of timing of elective Caesarean section on the respiratory outcome.
Methods: This was a retrospective study of all elective Caesarean sections on mothers with a gestational age of 37 weeks or more, that were performed in Tuen Mun Hospital from 1 January 2004 to 31 December 2009. Multiple pregnancies, fetuses with congenital anomalies, intrauterine deaths, and emergency Caesarean sections were excluded. Primary outcome measures of neonatal respiratory morbidity included transient tachypnoea of newborn, respiratory distress syndrome, persistent pulmonary hypertension of newborn, and pneumothorax. Only outcomes in Chinese women were analysed.
Results: A total of 31,420 term infants were delivered during the study period. After omitting infants because of special circumstances, 2602 infants delivered by elective Caesarean section and 23,208 babies delivered vaginally were included for analysis in this study. It was found that 43 (1.7%) infants of the elective Caesarean section group and 178 (0.77%) infants of those delivered vaginally suffered neonatal respiratory morbidity. Compared to those delivered vaginally, a significantly increased risk of combined respiratory morbidity was noted in babies delivered by elective Caesarean section between week 37+0 and week 37+6 of gestation (adjusted odds ratio=2.98; 95% confidence interval, 1.4-6.5; p=0.006), and in those of Chinese ethnicity only (adjusted odds ratio=3.15; 95% confidence interval, 1.3-7.4; p=0.008). The risk for transient tachypnoea of newborn was significantly increased in those delivered by elective Caesarean section between week 37 and week 38+0/38+6 in the total population, while the
increase in the Chinese was statistically significant only for deliveries before 38 weeks of gestation.

Conclusion: For Hong Kong Chinese infants, elective Caesarean delivery before 38 weeks of gestation is associated with significantly increased risk of neonatal respiratory morbidity. When considering elective Caesarean section before 38 weeks of gestation, obstetricians should carefully balance these risks and if feasible avoid the procedure.