Characteristics of included studies
| Study | Study design | Country/ setting | Intervention(s) description | Inclusion criteria | Confounders (variables, how measured) | Analysis method | Outcomes of interest | Total participants (n) |
| Seeland et al, 202020 | Retrospective database cohort | Derived from electronic health records of multiple healthcare organisations across 17 countries | Hormone use: estradiol and CHC. Hormone use was identified via RxNorm codes 4083 (estradiol), 4124 (ethinyl estradiol), progestins VA:HS800, and systemic contraceptives VA:HS200 | Pre-menopausal women aged 15–49 who were COVID-19-positive in the last 7 months | TriNetX analytics tools were used to assess baseline characteristics including ‘demographics, diagnoses, procedures, and medication’. No information on exactly which variables were collected or how they were measured | A logistic regression analysis was performed for the combined outcome variable ‘death’ incorporating the propensity score matching | Mortality | n=18 892 |
| Mujumdar et al, 202021 | Retrospective database cohort | Tertiary medical centre in the USA | Hormonal contraception including levonorgestrel-intrauterine device, progestin-only pills, CHC, and injectable progestin reported in medical chart | Reproductive age women ages 12–49 who tested COVID-19-positive | Uncertain | Logistic regression | Hospitalisation. Intubation | n=123 COVID-19-positive patients |
| Costeira et al, 202122 | Prospective cohort study | Users of the application in the UK | Combined hormonal oral contraceptive use (self-report) | Female app users aged 20–45 with BMI between 18–35 kg/m2 | Age, BMI, smoking status (self-reported) | Binomial generalised mixed models with a log-odds/logit link function used for association Age: continuous fixed effect. BMI: continuous fixed effect. Smoker: categorical fixed effect – never, former, and current. Sensitivity analyses performed to match the mean and median age of cases and controls for the exposure variables in subsets of users in 5-year age bins | Hospitalisation | n=295 689 |
| Chima et al, 202123 | Case series | 41 healthcare organisations participating in TriNetX - data for 8 patients in the USA | CHC Case definition: pulmonary embolism: defined using any ICD-10 root diagnostic code; medications 30 days before and after acute PE diagnosis and COVID-19 diagnosis | Paediatric patients <18 years old with PE and COVID-19-positive. PE diagnosed concurrently or within 30 days of COVID-19 diagnosis | Age, BMI, race, ethnicity, lab results, medications | Descriptive | Pulmonary embolism | n=6 girls |
| Hameed et al, 202124 | Case series | Multicentre multinational study – 10 tertiary care centres in Pakistan, Egypt, Singapore, and the USA | ‘Oral contraception’ CVT case definition: ‘Diagnosis of CVT was confirmed by at least one of the following imaging studies according to the established criteria: MR imaging, MR venography, CT, CT venography, or cerebral venography | Patients aged 18 or older with ‘recent COVID-19 infection, confirmed either by reverse transcriptase-polymerase chain reaction assay of a nasopharyngeal swab or serum antibody testing for COVID-19’ | ‘Risk factors, clinical features, laboratory findings, imaging findings, COVID-19-related information’ | Descriptive: frequencies and correlations | Cerebral venous thrombosis | n=7 women with CVT |
BMI, body mass index; CHC, combined hormonal contraception; CVT, cerebral venous thromboembolism; ICD-10, International Classification of Diseases, 10th revision; PE, pulmonary embolism.