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Caesarean section before 39 weeks raises risk of complications

Obstetrics and gynaecology

Obstetrics and gynaecology

Elective repeat caesarean deliveries at 37 or 38 weeks have a higher rate of respiratory and other neonatal complications than those carried out at 39 weeks gestation.

In a retrospective analysis of 13,258 elective repeat caesarean section (CS) procedures in the US, neonatal morbidity data was compared with the gestational age at delivery. The primary outcome was a composite of neonatal death and any adverse events including: respiratory complications, hypoglycaemia, newborn sepsis, confirmed seizures, need for resuscitation or ventilator support, admission to neonatal ICU, and prolonged hospitalisation.

Nearly half the deliveries (49%) were conducted at 39 weeks with an 8% neonatal complication rate. A total of 36% of deliveries were performed before the 39th week and the complication rates were 11% at 38 weeks and 15.3% at 37 weeks. Neonatal complications remained low at 40 weeks but rose thereafter to 11.3% at 41 and 19.5% at 42 weeks. There was only one neonatal death, this occurred in a baby born at 39 weeks. It is known that stillbirth rates rise after 40 weeks but this study was not set up to address this question.

Compared with births at 39 weeks, the adjusted odds ratio for the primary outcome was 2.1 (95% CI, 1.7-2.5) for those at 37 weeks and 1.5 (95% CI, 1.3-1.7; P for trend <0.001) for those at 38 weeks respectively.

Women who delivered before 39 weeks tended to be older and have a lower BMI and were significantly more likely to be white, married and have private insurance.

Over the past three decades CS rates have increased dramatically on both sides of the Atlantic. The reasons include patient demand, obstetrician convenience, a desire to avoid vaginal birth injury to the baby and of course repeat CS procedures in subsequent pregnancies.

This is the first paper I have ever seen where the complications of childbirth were actually higher in the white, affluent, women with private insurance. The reason appears to have been that these women preferred to have their elective procedure done as soon as term was reached and at a time convenient for both themselves and their doctors. Had they postponed their delivery it is estimated that the total number of serious neonatal complications would have been halved.

Elective caesarean deliveries should be conducted at 39 weeks gestation.

Tita ATN, Landon MB, Spong CY et al. Timing of repeat cesarean delivery at term and neonatal outcomes. N Engl J Med 2009;360:111-20

Reviewer

Chris Barclay
GP, Sheffield

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