[A population based study on incidence and determinants of preterm birth in Liuyang Hunan]

To describe the incidence and to discuss the risk factors of premature birth in rural areas of Liuyang.

We collected subjects from villages and towns in Liuyang through cluster sampling method. Before enrolling in this cohort, all of them had established health records from January 2010 to December 2011. We followed up the early, middle and late stages of pregnancy until delivery, and collected medical records and maternal health care manual of this cohort as our data materials. We explored the main influence factors of premature delivery by χ2 test and unconditional logistic regression analysis for single factor and multivariate analysis.

Among 6270 women who enrolled in our cohort, 259 were diagnosed as premature birth. The incidence (4.13%) was lower than the national average level. Non-conditional logistic regression analysis showed that the risk factors of premature birth were as follows: OR of placental abruption was 7.678 (95% CI: 2.249-26.215), that of premature rupture of fetal membranes (PROM) was 5.177 (95% CI: 3.945-6.793), that of uterine abnormal and deformity was 2.675 (95% CI: 1.007-7.107), that of placenta anomaly was 2.633 (95% CI: 1.666-4.162), that of hypertension in pregnancy was 2.172 (95% CI: 1.044-4.521), that of pregnancy complications was 1.806 (95% CI: 1.033-3.157), that of male fetus was 1.429 (95% CI: 1.086-1.881). Protective factors of preterm birth were too frequent prenatal examination (OR=0.502, 95% CI: 1.033-3.157) and single pregnancy (OR=0.155, 95% CI: 0.075-0.319).

Preterm delivery is caused by complicated factors, such as placental abruption, PROM and male fetus. Comprehensive measures should be taken to reduce preterm birth.