Variables independently associated with spontaneous preterm birth in all women studied: multiple analyses by non-conditional logistic regression [n = 2,227].

ORadj: Odds ratio adjusted for all predictors; CI: confidence interval of OR; p: p-value.Predictors entering the model: age (years); skin colour (white: 0/other: 1); marital status (with a partner: 0/without a partner: 1); schooling (until 8 years: 1/>8 years: 0); paid work in pregnancy (yes: 1/no: 0); homework (yes, totally or with help: 1/no: 0); parity (until 2: 1/≥3: 0); prenatal care (yes: 0/no: 1); adequacy of number of prenatal care visits (inappropriate: 1/appropriate: 0); weight gain at pregnancy (kg); initial BMI (kg/m2); final BMI (kg/m2); smoking during pregnancy (no: 0/yes, ≥1 cigarettes: 1); smoking until (0 to 9 months); Antenatal substance abuse (never used: 0/used and stopped at pregnancy, or used at pregnancy: 1); bacterial vaginosis during pregnancy (yes: 1/no: 0); urinary tract infection during pregnancy (yes: 1/no: 0); short cervix (yes: 1/no: 0); cervical insufficiency (yes: 1/no: 0); cerclage (yes: 1/no: 0); vaginal bleeding during pregnancy (yes: 1/no: 0); anaemia during pregnancy (yes: 1/no: 0); change in the volume of amniotic fluid (polyhydramnios: 1/no or oligohydramnios: 0); chronic disease: hypertension (yes: 1/no: 0); gestational hypertension (yes: 1/no: 0); foetal malformation (yes: 1/no: 0); foetal growth restriction (yes: 1/no: 0); other foetal morbidity (yes: 1/no: 0); multiple pregnancy (yes: 1/no: 0).Variables independently associated with spontaneous preterm birth in all women studied: multiple analyses by non-conditional logistic regression [n = 2,227].