NEW YORK (Reuters Health) - Elective repeat cesarean delivery at term but before 39 weeks is associated with higher rates of adverse outcomes, physicians in the US report in the New England Journal of Medicine for January 8.
Roughly 40% of elective cesarean deliveries in the US are repeat procedures, Dr. Alan T. N. Tita, at the University of Alabama at Birmingham, and co-authors note, and even though they are generally proscribed before 39 weeks, they may be scheduled earlier "to accommodate patient and physician convenience."
To assess the potential risk involved, the researchers studied 13,258 elective repeat cesarean deliveries conducted at term (i.e., 37 weeks of gestation or longer) at 19 centers from 1999 through 2002. The team found that 6.3% were performed at 37 weeks, 29.5% at 38 weeks, and 49.1% at 39 weeks of gestation.
The incidence of the primary outcome -- the composite of any adverse outcome or death -- was 8.0% at week 39, 11.0% at week 38, and 15.3% at week 37. Compared with births at 39 weeks, those at 37 weeks and 38 weeks were associated with adjusted odds ratios for adverse outcome of 2.1 and 1.5, respectively (p for trend < 0.001).
"One neonatal death, and no cases of hypoxic-ischemic encephalopathy or necrotizing enterocolitis were observed in this select cohort of low-risk term births," the authors note.
However, the risk of respiratory distress syndrome was quadrupled among births at 37 weeks, and doubled among those at week 38. The odds of NICU admission, sepsis, hypoglycemia, or extended hospitalization was more than twice as high at 37 weeks as at 39 weeks; and except for hypoglycemia, such events were still significantly elevated at 38 weeks.
Moreover, deliveries occurring during the last 3 to 4 days of the 38th week of gestation were still associated with increased neonatal morbidity, the investigators note.
Dr. Tita's group observed similar trends toward increasing risk for deliveries at week 41 (OR 1.4) and week 42 or higher (OR 2.5).
Thus, these findings leave "a relatively narrow 2-week window of minimal risk in which elective repeat cesarean deliveries could optimally be performed," writes Dr. Michael F. Greene, at Massachusetts General Hospital in Boston, in an accompanying editorial.
Reference:
N Engl J Med 2009;360:111-120,183-184.
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