A case-control study of preterm delivery risk factors according to clinical subtypes and severity

Abstract

Aims: To examine risk factors of preterm delivery (PTD) among Thai women. Methods: Our case–control study included 467 term controls and 467 PTD cases. PTD was studied in aggregate and in subgroups (i.e. spontaneous preterm labor and delivery [SPTD], preterm premature rupture of membrane [PPROM], medically indicated preterm delivery [MIPTD], moderate preterm delivery [32–36 weeks], and very preterm delivery [2), compared with normal weight women (18.5–24.9 kg/m²), had a 1.70‐fold increased risk of PTD (95%CI: 1.21, 2.39). Risk of SPTD (OR = 2.16, 95%CI: 1.44, 3.24) and very PTD (OR = 2.45, 95%CI: 1.35, 4.45) were also elevated in lean women. Conclusions: Maternal age, pre‐pregnancy body mass index, prior history of PTD and no utilization of prenatal care were covariates identified in this study as risk factors for PTD. Our findings also suggest heterogeneity in risk factors for clinical subtypes of PTD.