Objective: To determine outcomes of pregnancies in women at least 44 years of age and to determine factors predicting cesarean delivery in these patients. Methods: Between January 1988 and December 1995, 109 women at least 44 years old delivered in our medical center. These women were matched to a group of 309 women 20-29 years of age. Multiple logistic regression analysis was used to evaluate the association between maternal age and outcome variables, controlling for possible confounding factors. Based on the logistic regression, a predictive model was calculated for cesarean delivery and validated prospectively in a separate group of 30 consecutive women at least 44 years old, who delivered during the first 8 months of 1996. Results: Very advanced maternal age, compared with younger age, was associated with a significantly higher rate of medical complications (hypertensive disorder and diabetes) (odds ratio [OR] 2.5; 95% confidence interval [CI] 1.5, 4.1; P<.001), instrument-assisted vaginal delivery (OR 7.5; 95% CI 2.2, 25.0; P<.004), and cesarean delivery (OR 7.3; 95% CI 2.2, 16.7; P<.001). The incidences of preterm labor, premature rupture of membranes, emergency cesarean delivery, meconium-stained amniotic fluid, small for gestational age newborns, and 5-minute Apgar scores of 7 or lower were not influenced by maternal age. The regression model showed an increased risk for cesarean delivery associated with age of at least 44 years (OR 7.3; 95% CI 2.2, 16.7), primiparity (OR 3.5; 95% CI 1.3, 9.8), infertility treatment (OR 3.6; 95% CI 1.5, 8.8), and egg donation (OR 19.5; 95% CI 6.1, 62.2), with positive and negative predictive values of 94 and 86%, respectively. Conclusion: Maternal age of at least 44 years is associated with medical complications in pregnancy and more interventions during labor. However, overall pregnancy outcomes are favorable. Cesarean delivery can be predicted accurately based on maternal age, parity, and infertility treatment.