Objective: To identify the clinical characteristics of pregnancy associated group A streptococcus (GAS) infection and predictors for intensive care unit (ICU) admission. Design: A retrospective cohort study of culture-proven pregnancy-related GAS infections. Setting and population: a tertiary university-affiliated hospital between 1/2008-7/2020. Methods: Review patient’s electronic records of patients. Main outcome measures: Incidence of pregnancy associated GAS, proportion given prophylaxis and admission to ICU. Results: Of the 143,750 who delivered during the study period, 66 (0.04%) were diagnosed as having a pregnancy associated GAS infection. Fifty-seven of them (86.3%) presented postpartum, and nine (13.6%) had septic abortions. The most common presenting signs and symptoms among puerperal GAS, were postpartum pyrexia (72%), abdominal pain and/or tenderness (33%), and tachycardia (>100 bpm, 22%). Thirteen women (19.6%) developed streptococcal toxic shock syndrome (STSS): 10 of them delivered vaginally, two had caesarean deliveries. Predictors for STSS and ICU admission were: antibiotic administration >24 hours from presentation postpartum, tachycardia, and a C-reactive protein level >200 mg/L. Women that received antibiotic prophylaxis during labour had a significantly lower rate of STSS (0 vs 10, 22.7%; P = 0.04), as evidenced by the delayed interval from delivery to the first presentation of infection among those who received prophylaxis during labour (8 ± 4.8 vs 4.8 ± 4.2 hours, P = 0.008). Conclusion: Deferral of medical intervention >24 hours from the first registered abnormal sign had the most important impact on deterioration of women with invasive puerperal GAS. Antibiotic prophylaxis during labour in women with GAS may reduce complications