Objectives: 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.
Study design: 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.
Results: 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.
Conclusion: 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.