Background: The findings of individual epidemiological studies that suggest an association between some Persistent Organic Pollutants (POPs) and Gestational Diabetes Mellitus (GDM) are inconclusive. Objectives: To estimate the strength of the association between POPs exposure and GDM in a systematic review with meta-analysis. Search strategy: MEDLINE, Scopus, and Web of Science were searched until 2022. Selection criteria: Cohort and case-control studies analyzing the association between POPs and GDM in healthy pregnant women. Data collection and analysis: Quality was assessed using QUIPS scale and standardized mean differences (SMD) and 95% confidence intervals (CI) was pooled using random-effect model. Main results: Fourteen articles including 11,422 participants were selected. The risk of bias of included studies was high in 4 (28.6%), moderate in 9 (64.3%) and low in 1 (7.14%). Only six POPs showed a significative SMD between GDM cases and controls: Perfluorobutanesulfonic acid (PFBS) 0.33 (95% CI 0.23, 0.43; I2=0%); Perfluorodecanoic acid (PFDA) -0.11 (95% CI -0.20, -0.01, I2 = 0.0%); 2,2’,3,4,4’,5,5’-Heptachlorobiphenyl (PCB 180) 0.37 (95% CI 0.19, 0.56; I2=25.3%); 2,2’,4,4’,5-Decabromodiphenyl ether (BDE 99) 0.36 (95% CI 0.14, 0.59; I2=0%); 2,2’,4,4’,6-Decabromodiphenyl ether (BDE 100) 0.42 (95% CI 0.19, 0.38; I2=0%); and, Hexachlorobenzene (HCB) 0.22 (95% CI 0.01, 0.42, I2=39.6%). For other POPs, no statistically significant association was observed. Conclusion: The available evidence is variable on quality and results were heterogeneous making impossible to establish a clear association between POPs exposure and risk of GDM. Improve the methodology of epidemiological studies assessing the association of POPs and risk of adverse clinical outcomes are needed.

Objective: to establish a prognostic model informing optimal timing of delivery in women with late preterm preeclampsia. Design: development and validation of a prognostic model Setting: prospective cohort study, nested in the PHOENIX trial, in 36 maternity units across England and Wales. Population: women with late preterm pre-eclampsia (34+0-36+6 weeks’ gestation) Methods: prospective recruitment of women in whom blood samples for Placental Growth Factor (PlGF) and soluble fms-like tyrosine kinase-1 (sFlt-1) testing was obtained, alongside clinical data, for use within the ‘Prediction of complications in early-onset pre-eclampsia’ (PREP)-S model. Candidate variables were compared using standard methods (sensitivity, specificity, Receiver Operator Curve areas). Estimated probability of early delivery from PREP-S was compared to actual event rates by calibration. Main Outcome Measures: clinically indicated need for delivery for pre-eclampsia within seven days. Results: PlGF testing had high sensitivity (97.9%) for delivery within seven days, but negative predictive value was only 71.4%, with low specificity (8.4%). The area under the curve for PREP-S was 0.64 (standard error (SE) 0.03), for PlGF was 0.60 (SE 0.03), and 0.65 (0.03), and 0.64 (0.03) for PREP-S in combination with PlGF and sFlt-1:PlGF, respectively. Conclusions: PlGF-based testing does not add to clinical assessment to determine need for delivery in late preterm pre-eclampsia. Existing models developed in women with early onset pre-eclampsia to predict complications cannot be used to predict clinically indicated need for delivery in women with late preterm pre-eclampsia. Funding: NIHR HTA Monitoring Add on Studies Programme (reference 15/59/06). Keywords: placental growth factor, preeclampsia, prognosis