Surgical site infection (SSI) following caesarean section is common, resulting in significant morbidity. Several factors are known to contribute to wound infection, including maternal, procedural and antibiotic factors. We sought to clarify these issues and sought opportunities to make improvements. A retrospective cohort study was performed assessing all women who underwent caesarean section in 2014 and 2015 at Wellington Hospital. Any women with culture‐positive wound samples within 30 days of surgery were identified, and clinical notes reviewed. Odds ratios (OR) were calculated for available maternal, procedural and antibiotic risk factors. Two simplified surveillance techniques were also tested for their abilities to identify significant trends. The study included 2231 women, of whom 116 (5.2%) were identified as having SSI. Maternal obesity (body mass index (BMI) ≥ 30) was associated with significant SSI risk (OR 4.1, P < 0.001). The pathogen distribution was significantly different between women with BMI < 30 and BMI ≥ 30 (P < 0.001). Increased cefazolin dose based on BMI (3 g dose for BMI ≥ 30) was associated with a significant reduction in SSI (OR 0.309, P < 0.001) and was administered in 74.1% of obese women receiving cefazolin. Māori women had an increased SSI risk (OR 2.1, P = 0.019), as did Samoan women (OR 3.0, P = 0.002). The study reinforces other studies showing that raised BMI is the single biggest risk factor for surgical site infection post‐caesarean section. Surveillance using simplified techniques appears to be adequate to identify trends. We believe that concentrating on appropriate antibiotic dosing and targeting special wound care measures will be pivotal interventions in improving outcomes in high‐risk groups.