Background: Existing reviews of pre-eclampsia determinants have focused on clinical and genetic risk factors. Objective: To evaluate social determinants for pre-eclampsia prevention. Search strategy: Systematic searches were conducted on relevant electronic databases to 31 st July 2023. Selection criteria: Reviews and large cohort studies (≥1,000 participants), published within the last 10 years, reporting quantitative associations between social determinant exposures and pre-eclampsia outcomes. Data collection and analysis: Titles and abstracts and then relevant full-texts were reviewed by two reviewers, independently. Strength of association was evaluated as ‘definite’ (odds ratios [OR] or relative risk [RR] ≥3.00 or <0.33), ‘probable’ (OR or RR 1.50-2.99 or 0.33-0.67), ‘possible’ (OR or RR 1.10-1.49 or 0.68-0.89), or ‘unlikely’ (OR or RR 0.90 - 1.09). Quality of the evidence was high, moderate, low, or very-low, using GRADE. Main results: Twenty-six publications found 22 associations of pre-eclampsia with socioeconomic status, social support/exclusion, healthcare access, and occupational and physical environmental factors. One association (polygamy) was definite (low-quality evidence). Probable associations included: work stress and lack of antenatal care (high-quality evidence); prolonged occupational exposure to whole body vibrations or bending, elevated temperatures beyond seasonal norms, and UV-B radiation exposure (protective factor), all based on moderate-quality evidence; and Asian/Oceanian origins (protective, low-quality evidence). There were 11 possible associations, which did not include education. Conclusion: Our findings support recommendations to address climate change, strengthen occupational protection, and promote early ANC attendance. Social determinants may be indicative of upstream factors (e.g., obesity) that increase likelihood of clinical risk factors for pre-eclampsia incidence and severity.

Objectives To assess associations between pre-pregnancy BMI and severe maternal morbidity (SMM), perinatal death and neonatal morbidity in twin pregnancies. Design Retrospective cohort study. Setting British Columbia, Canada (2000-2017). Population All twin births at ≥20 weeks’ gestation. Methods We examined associations between pre-pregnancy BMI, categorized as underweight (BMI <18.5m/kg2), normal BMI (18.5m/kg2 BMI <25m/kg2), overweight (25m/kg2 BMI <30m/kg2) and obese (BMI ≥30m/kg2) and adverse maternal and perinatal outcomes, using targeted maximum-likelihood estimation, adjusted for demographics and obstetric history. Outcomes SMM, perinatal death, severe perinatal morbidity. Results Overall, 7770 (368 underweight, 1704 overweight and 1016 obese) women with twin pregnancy were included. The rates of SMM (per 10,000 pregnancies) were: 271.1, 320.4, 270.0 and 225.9 in underweight, normal BMI, overweight and obese women, respectively. Underweight women had higher rates of the composite perinatal adverse outcome (adjusted rate ratio) [aRR] = 1.79, 95%CI = 1.32- 2.43), largely driven by increased rates of severe respiratory distress syndrome, and neonatal death (aRR = 2.81, 95%CI = 1.64-4.83). There was no evidence of elevated risk for perinatal outcomes among overweight and obese women. Conclusions In this population-based study cohort study, we found no evidence of an increased risk of adverse maternal and perinatal outcomes in overweight and obese women with twins; however, infants of underweight women are at higher risk of neonatal death and morbidity. These findings have implications for pregnancy care of women with twin pregnancies, especially those who are underweight. Funding SickKids Foundation (SKF-154852) Keywords: pre-pregnancy obesity, maternal morbidity, perinatal death