Outcomes of pregnancy beyond 37 weeks of gestation.

OBJECTIVE: The aim of the study was to evaluate pregnancy outcomes by weeks of gestation. A second aim was to assess the outcomes in groups with spontaneous or induced labor.

METHODS: This was a prospective cohort study of singleton pregnancies delivered after 37 weeks of pregnancy covering a well defined region in Norway from 1990 to 2001 (N = 27,514). Linear regression, chi 2 tests, and multivariable logistic regression analysis were used.

RESULTS: Maternal complications varied with gestational age, and were lowest at 39 weeks and highest postterm (cesarean delivery 12.3-21.6%, operative vaginal delivery 10.7-15.4%, maternal hemorrhage 9.7-14.6%). Poor neonatal outcome varied with gestational age only for spontaneous labors (Apgar at 5 minutes less than 7 1.0-2.3%, pH less than 7.10 3.4-5.2%), whereas induction of labor was a risk factor for delivery complications (odds ratio 1.3-2.8), independent of gestational weeks.

CONCLUSION: Poor pregnancy outcomes vary with gestational age. Postterm pregnancy and induced labor are prognostic factors for poor outcome.