International Journal of Gynecology and Obstetrics 86 (2004) 70–78 0020-7292/04/$30.00  2004 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.ijgo.2004.04.003 Special article Risk factors for preterm birth in Vietnam N. Nguyen , D.A. Savitz *, J.M. Thorp a,b b,c, d Hanoi Obstetrics and Gynecology Hospital, Hanoi, Vietnam a Department of Epidemiology, School of Public Health, University of North Carolina, Chapel Hill, NC 27599-7435, USA b Carolina Population Center, University of North Carolina, Chapel Hill, NC, USA c Division of Maternal and Fetal Medicine, Department of Obstetrics and Gynecology, School of Medicine, d University of North Carolina, Chapel Hill, NC, USA Received 8 March 2004; received in revised form 14 April 2004; accepted 15 April 2004 Abstract Objective: To identify the risk of preterm birth and possible determinants among women in Hanoi, Vietnam. Method: Prospective cohort study of 1709 women with singleton live births at Hanoi Obstetrics and Gynecology Hospital, Hanoi, Vietnam, June–October 2002. Logistic regression analysis was used to examine predictors of preterm birth (-37 weeks’ gestation). Result: The risk of preterm birth was 11.8%. Physically demanding work during pregnancy, two or more prior spontaneous abortions, history of preterm birth, vaginal bleeding, inadequate prenatal care during the first 20 weeks of gestation, and history of intrauterine device use with removal less than 12 months before the current pregnancy were associated with increased risk of preterm birth (adjusted odds ratios between 1.8 and 2.6). Conclusion: Preterm birth is relatively frequent in this population. Beyond established risk factors, these data implicated agricultural work and physical work demands with preterm birth, as well as history of recent IUD use.  2004 International Federation of Gynecology and Obstetrics. Published by Elsevier Ireland Ltd. All rights reserved. Keywords: Preterm birth; Pregnancy outcome; Epidemiology 1. Introduction Preterm birth, delivery before completion of 37 weeks of gestation, is a major determinant of neonatal morbidity and mortality in both developed and developing countries w1x. The risk of preterm birth was estimated as 8.7 and 11.2% in recent reports from Vietnam w2x, but these are not repre- *Corresponding author. Tel.: q1-919-966-7427; fax: q1- 919-966-2089. E-mail address: david_savitz@unc.edu (D.A. Savitz). sentative of the entire Vietnamese population because of geographic differences in health care quality and the level of hospital from which participants were recruited. Socioeconomic and cultural factors and the dis- tribution of several potential risk factors for pre- term birth are quite distinctive in Vietnam compared to western populations. For example, cigarette smoking, alcohol use, and illicit drug use are very rare w3x, physical work demands for women are substantial and work continues to the