Cesarean sections in a birth center.

OBJECTIVE To estimate the prevalence of cesarean sections in a birth center of a hospital and identify factors associated. METHODS Cross-sectional study including medical records of 2,441 births assisted in a birth center in the city of São Paulo, southeastern Brazil, between March and April 2005. The dependent variable (type of delivery) included vaginal delivery and cesarean section. The independent variables were grouped into four categories: demographic characteristics; current and past obstetric history; intrapartum care; and perinatal outcomes. Prevalence ratios and 95% confidence intervals (95% CI) were estimated to assess the association between type of delivery and maternal and newborn variables. RESULTS Of all deliveries, 14.9% were cesarean sections. Cesarean section in the current pregnancy was associated with past cesarean sections (PR = 3.19, 95%CI: 2.64,3.84); gestational age > 40 weeks (PR = 1.32, 95%CI: 1.09;1.61); cervical dilation of up to 4 cm on admission (PR = 3.22, 95%CI: 2.31;4.50); and meconium-stained amniotic fluid (PR = 2.5, 95%CI: 2.05;3.06). Regarding newborn characteristics cesarean section was associated with birth weight >4 kg (PR = 1.86, 95%CI: 1.29;2.66). Among women with history of past cesarean sections, having had also a prior vaginal delivery was a protective factor for cesarean section in the current pregnancy (PR = 0.46, 95%CI: 0.30;0.71). Factors related to fetal conditions including fetal stress, meconium-stained amniotic fluid, breech presentation and macrosomia accounted for 47.8% (175) while those related to the mechanism of birth including arrest disorders, functional dystocia and malposition accounted for 31,3% (115) of all indications for a cesarian section [corrected]. CONCLUSIONS Prevalence of c-section was consistent with World Health Organization recommendations. Increased risk of c-section was associated with prior history of c-sections, cervical dilation of at least 4 cm upon admission, gestational age > 40 weeks, meconium-stained amniotic fluid, and birthweight > 4 kg.