Mode of delivery
Birth trauma, hypoxia, and metabolic acidosis increase neonatal morbidity and mortality in the preterm infant. Therefore, there have been concerns regarding the best method to manage the second stage of labour when the fetus may be most at risk.
In extremely preterm infants, even a partially dilated cervix may allow the fetus to deliver. Due to a disproportionate growth of the head, entrapment of the aftercoming head may occur. At very early gestations, the lower segment of the uterus is not clearly formed and a classical caesarean section, or high transverse incision, may need to be performed. The implications for the next pregnancy include increasing the risk of placenta accreta, uterine rupture, and a repeat caesarean section for delivery. Although caesarean section will reduce intrapartum stillbirths, it is not clear that it improves overall neonatal survival.A Cochrane meta-analysis of four trials with (n = 116) showed less respiratory distress syndrome, less neonatal seizures, and fewer deaths within the caesarean group (93). In contrast, a longitudinal cohort study of women with delivery between 20 and 26 weeks and a subsequent birth, index caesarean delivery (n = 386) and index vaginal delivery (n = 2086) showed similar risks of composite morbidity (16.1% vs 15.4%; P = 0.76) and subsequent haemorrhage (9.6% vs 11.1%; P = 0.39). Women with index caesarean were more likely to experience a future uterine rupture (1.8% vs 0.1%; P based cohort study. BMJ 2012;344:e896.
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