Figure 1

SSI rates according to patient group and period of observation. Period 1 was the first period of treatment with doxycycline and metronidazole (white bars). Period 2 was the period when cephalothin and metronidazole was used (grey bars). Period 3 was the period when we returned to doxycycline and metronidazole (black bars). The gynaecology department continued use of cephalothin and metronidazole during period 3 (i.e., same regimen during period 2 and 3). The obstetric (control) patients did not change the antibiotic regimen during the study period (i.e., hatched bars). Detailed data are provided in Additional File 2.