Background: Obesity increases risk of pre-eclampsia, but the association with hemolysis, elevated liver enzymes, and low platelets (HELLP) syndrome is understudied. Objective: To examine the association between pre-pregnancy body-mass-index (BMI) and HELLP syndrome, including early- vs. late-onset disease. Study Design: A retrospective cohort study, population-based data. Setting: British Columbia (BC), Canada, 2008/09-2019/20. Population: All pregnancies resulting in live births or stillbirths at ≥20 weeks’ gestation. Methods: BMI categories (kg/m 2) included: underweight (<18.5), normal (18.5-24.9), overweight (25.0-29.9), and obese (≥30.0). Rates of early- and late-onset HELLP syndrome (<34 vs. ≥34 weeks, respectively) were calculated per 1000 ongoing pregnancies at 20- and 34-weeks’ gestation, respectively. Cox regression was used to assess the associations between risk factors (BMI and, e.g., maternal age, parity) and early- vs late-onset HELLP syndrome. Main outcome measures: HELLP syndrome. Results: The rates of HELLP syndrome per 1000 women were 2.8 overall (1,116 per 391,941 women), and 1.9, 2.5, 3.2 and 4.0 in underweight, normal BMI, overweight and obese categories, respectively. Overall, gestational age-specific rates increased with pre-pregnancy BMI. Adjusted hazard ratio [AHR] was 2.24 for early-onset (95% confidence interval [CI] 1.65-3.04) vs. AHR 1.48 (95% CI 1.23-1.80) for late-onset HELLP syndrome (p-value for interaction 0.025). Chronic hypertension, multiple gestation, hemorrhage (<20 weeks’ gestation and antepartum) also showed differing AHRs between early- vs. late-onset HELLP. Conclusions: Pre-pregnancy BMI is positively associated with HELLP syndrome and the association is stronger with early-onset HELLP syndrome. Associations with early- and late-onset HELLP syndrome differed for some risk factors, suggesting possible differences in etiologic mechanisms.

Objective: To examine the association between maternal stature and adverse perinatal outcomes, and the modifying effect of race/ethnicity. Design: Retrospective cohort study. Settings: USA, 2016-2017. Population: Women with a singleton stillbirth or livebirth (N=7,361,713). Methods: Using data from the National Center for Health Statistics, short and tall stature were defined as <10th and >90th centile of the maternal height distribution. Logistic regression was used to obtain adjusted odds ratios (AOR) and 95% confidence intervals (CI). Main Outcome Measures: Preterm birth (PTB, <37 weeks’ gestation), perinatal death, and the composite of perinatal death/severe neonatal morbidity (PD/SNM). Results: Short women had elevated risk of adverse outcomes, while tall women had a decreased risk relative to average stature women. Short women had an increased risk of perinatal death and PD/SNM (AOR=1.14, CI: 1.10-1.17; AOR=1.21, CI: 1.19-1.23, respectively). The association between short stature and perinatal death was attenuated in non-Hispanic Black women compared with non-Hispanic White women (AOR=1.10, 95% CI 1.03-1.17 vs AOR=1.26, CI 1.19-1.33). Compared with women of average stature, tall non-Hispanic White women had lower rates of PTB, PD/SNM (AOR=0.82, CI 0.81-0.83; AOR=0.95, CI 0.91-1.00; AOR=0.90, CI 0.88-0.93, respectively). Conclusion: Relative to women of average stature, short women have an increased risk of adverse perinatal outcomes; these effects are attenuated in Hispanic women, and for some adverse outcomes in non-Hispanic Black women. All tall women have a lower risk of preterm birth, and tall non-Hispanic White women have also lower risk of perinatal death/severe neonatal morbidity.

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