Assessment of risk factors and predictors for spontaneous pre-term birth in a South Indian antenatal cohort

Objective: To assess incidence of spontaneous preterm births and determine biochemical and obstetric risk factors for spontaneous pre-term births in a cohort of antenatal women visiting a secondary care hospital. Methods: A prospective cohort study was designed to include 1420 pregnant women coming for antenatal care at a secondary care hospital. The cohort was followed throughout pregnancy and relevant history, obstetric and ultrasonographic examination and biochemical investigations was carried out in 2nd (20-24 weeks period of gestation) and 3rd trimester (28-32 weeks period of gestation). Outcome of delivery was noted for all the subjects. Results: A total of 1133 women were recruited. Among the 1071 respondents, 11 had abortions, 93.1% delivered at term while 5.9% had preterm deliveries. Preterm deliveries were noted among 6.5% women with short stature, 13.3% with cervical length <2.5. cms and 5.2% among women with anaemia. Statistically significant association was noted between Oligohydramnios, IUGR and preterm births. Salivary estriol was lower in women who had preterm births as compared to term births. Conclusions: The incidence of preterm births (5.9%) was low in the present cohort. Oligohydramnios and Intrauterine Growth Retardation (IUGR) were identified as significant risk factors for preterm births. Conventional risk factors like short cervix, short stature and biochemical inflammatory markers were not identified as predictors of prematurity. Lower levels of salivary estriol identified among women at risk of preterm births demonstrates the utility of the test as a non-invasive investigation for early identification of preterm births.