- To determine the prevalence of malpresentation among preterm births and to evaluate the clinical significance of malpresentation as a predictor of neonatal complications in preterm delivery. A cross-sectional study was conducted comparing 692 nonvertex preterm deliveries of singleton births (24-36 weeks) to 4685 vertex preterm deliveries. Women with gestational age less than 24 weeks and birthweight <500 g were excluded from the study. The study population included 5377 women who met the inclusion criteria. The prevalence of malpresentation was 12.8% (692/5377); 73% in the breech presentation, 22% in the transverse lie, and 5% in other positions. The mean gestational age at birth was significantly lower in the nonvertex group (32.4+/- 3.5 vs. 34.2+/-2.6; P<0.0001). Higher rates of perinatal mortality (23.1% vs. 10.1%; P<0.0001) were observed in the nonvertex group when compared with vertex births, as well as other complications such as oligohydroamnion (9.2% vs. 3.2%; P<0.0001); small-for-gestational-age; (10.5% vs. 5.9%; P<0.001); congenital anomalies (11% vs. 5.9%; P<0.001); placental abruption (8.7% vs. 4. 1%; P<0.0001); placenta previa (6.8% vs. 2.5%; P<0.0001); premature rupture of membranes (25.4% vs. 16.6%; P<0.0001); chorioamnionitis (7.9% vs. 2.9%; P<0.001); prolapse of cord (2.3% vs. 0.6%; P<0.0001) and cesarean section rate (63.9% vs. 19.1%; P<0.0001). Neonatal mortality was found to be higher for breech presentation, odds ratio (OR)=4 (confidence interval [CI]=2.76-4; P<0.0001), transverse lie, OR=2.1 (1.1-4.12; P<0.02) and for other malpositions, OR=7.3 (2. 72-20; P<0.0001). After multivariate adjustment for birthweight, cesarean section, placental pathology and chorioamnionitis, a strong association remained between the presence of breech presentation and neonatal mortality, with an adjusted OR of 2.2 (CI=1.36-3.63; P<0.01). The adjusted OR for the two other groups of malpresentation was not statistically significant. Breech presentation in preterm delivery is an independent risk factor for neonatal mortality after simultaneous adjustment for birthweight, chorioamnionitis and placental pathology. Cesarean section was found to have a protective effect on neonatal mortality rates.