[Sociodemographic and obstetric factors associated with preterm birth]

Preterm birth is the major cause of neonatal morbidity and mortality and is responsible for 75 to 90% of neonatal deaths unrelated to congenital malformations.

To evaluate preterm birth association with sociodemographic and obstetric risk factors.

A retrospective, comparative, longitudinal and observational study was carried out in which were analyzed all preterm births registries found in 2001-2006 period in the Civil Hospital of Culiacan, Sinaloa, México. As controls were selected at random the clinical registries of patients who presented term birth (n = 755). Were analyzed the association between preterm birth with sociodemographic factors (maternal age, socioeconomic level, tobacco use, alcoholism, begin intercourse age, number of sexual partners) and obstetric factors (transvaginal bleeding in the first half of pregnancy, previous preterm birth, post abortion and pregnancy at term interval, premature rupture of membranes, anemia and urinary infection).

Significant differences were found between cases and controls about socioeconomic level (OR: 0.71; IC 95%: 0.5-0.9; p = 0.0191), vaginal bleeding in first half of pregnancy (OR: 31.06; IC 95%: 7.5-127.6; p < 0.05), previous preterm birth antecedent, (OR: 9.33; IC 95%: 2-59.1; p = 0.0006), pregnancy at term interval < or = one year (OR: 1.79; IC 95%: 1.2-2.5; p = 0.0021), premature rupture of membranes (OR: 9.24; IC 95%: 6.1-13.9; p < 0.05) and urinary infection (OR: 3.72; IC 95%: 2.1-6.4; p < 0.05). There were not association with the other factors analyzed.

Preterm birth was significantly associated to socioeconomic level, transvaginal bleeding in first half of pregnancy, preterm birth previous, interpregnancy interval equal or less than one year, premature rupture of membranes and urinary infection.