These authors contributed equally to this work.
A case–control study of preterm delivery risk factors according to clinical subtypes and severity
Article first published online: 11 JAN 2010
© 2010 The Authors. Journal compilation © 2010 Japan Society of Obstetrics and Gynecology
Journal of Obstetrics and Gynaecology Research
Volume 36, Issue 1, pages 34–44, February 2010
How to Cite
Ip, M., Peyman, E., Lohsoonthorn, V. and Williams, M. A. (2010), A case–control study of preterm delivery risk factors according to clinical subtypes and severity. Journal of Obstetrics and Gynaecology Research, 36: 34–44. doi: 10.1111/j.1447-0756.2009.01087.x
Disclosure of Interest: No conflicts of interest.
- Issue published online: 4 FEB 2010
- Article first published online: 11 JAN 2010
- Received: September 16 2008.Accepted: February 4 2009.
- gestational length;
- preterm delivery;
- risk factors
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 [<32 weeks]). We used multivariable logistic regression procedures to estimate odds ratio (OR) and 95% confidence intervals (CI) of potential PTD risk factors.
Results: Advanced maternal age (≥35 years) was associated with a 2.27-fold increased PTD risk overall (95%CI: 1.40, 3.68); and with a 3.79-fold increased risk of MIPTD (95%CI: 1.89, 7.59). Young maternal age (<20 years) was associated with a 2.07-fold increased risk of SPTD (95%CI: 1.19, 3.61). Prior history of PTD was associated with a 3.64-fold increased PTD risk overall (95%CI: 1.87, 7.09), and with a 5.69-fold increased risk of MIPTD (95%CI: 2.44, 13.24). No prenatal care was associated with all PTD subtypes. Lean women (body mass index < 18.5 kg/m2), 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.