[Social-economic and obstetric factors associated to premature rupture of membranes]

The premature rupture of membranes is the delivery of amniotic liquid after 20 weeks of gestation and before the beginning of labour.

To evaluate the association between premature rupture of membranes and sociodemographics and obstetrics antecedents.

Unmatched case-control study carried out in patients from Hospital Civil de Culiacan, Sinaloa (Mexico), from January 2003 to December 2006. Risk factors frequency was compared in women with and without premature rupture of membranes (cases: 1,399; controls: 1,379). Most important variables were: socio-economic level, smoking, and gyneco-obstetric history (sexual partners, pregnancies, newborns, abortions, prenatal control and intergenesic interval). Odds ratio, crude and adjusted, and interval of confidence (IC 95%) were obtained by means of non-conditional logistic regression models.

Prevalence of premature rupture of membranes was 8.9%. Socio-economic level was similar in both groups. Premature rupture of membranes was associated with smoking, beginning of sexual activity, and intergenesic interval. History of two or more cesarean sections was considered a protective factor of premature rupture of membranes. Number of sexual partners was marginally meaningful (p = 0.053). Preterm birth frequency was higher in cases group. Resolution of pregnancy was the same for both groups (p = 0.233).

Premature rupture of membranes was significantly associated with smoking, beginning of sexual activiti, intergenesic interval and a preterm birth history. Two or more previous caesarean sections were considered as protective factor.