Cochran-Armitage trend test for socio-economic variables; maternal educational level and household annual income.

Effects on number of treatments, and use of any antibiotics, UTI antibiotics and RTI antibiotics in pregnancy.* : Low (elementary school or college graduate), Medium (tradesman or medium length), High (university candidate).** : Low (below 50.000 Euro), Medium (50.000 - 110.000 Euro), High (above 110.000 Euro).*** : Received more than one antibiotic treatment during pregnancy.