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Importance: Early preterm birth (ie, at less than 34 weeks' gestation) confers a high risk for adverse health outcomes, yet no universal screening strategy exists, preventing targeted delivery of effective interventions., Objective: To evaluate the ability of midpregnancy placental growth factor (PlGF) screening to identify pregnancies at highest risk for early preterm birth., Design, Setting, and Participants: This prospective cohort study was conducted at an urban, tertiary care center from 2020 to 2023. Participants were unselected, pregnant people with singleton pregnancies, receiving universal-access prenatal care from obstetricians, family physicians, or midwives, who underwent a PlGF test at the time of routine gestational diabetes screening, typically at 24 to 28 weeks' gestation. Data were analyzed from January to May 2024., Exposure: PlGF level less than 100 pg/mL at the time of gestational diabetes screen., Main Outcomes and Measures: The primary outcome was all early preterm birth, defined as less than 34 weeks' gestation. Secondary outcomes included iatrogenic preterm birth, spontaneous preterm birth, preeclampsia, stillbirth, and small-for-gestational-age birth weight., Results: Among 9037 unique pregnant individuals, 156 (1.7%) experienced early preterm birth (52 spontaneous births; 104 iatrogenic births). The area under the curve (AUC) for PlGF and early preterm birth was 0.80 (95% CI, 0.75-0.85). Low PlGF level was associated with early preterm birth (positive likelihood ratio [LR], 79.400 [95% CI, 53.434-115.137]; negative LR, 0.606 [95% CI, 0.494-0.742]; specificity, 99.5% [95% CI, 99.3%-99.6%]; negative predictive value, 98.9% [95% CI, 98.8%-99.1%]). Time to birth from PlGF test was significantly reduced among patients with a PlGF level less than 100 pg/mL, among whom more than 50% delivered within 50 days of testing. Individuals with a low PlGF level made up more than 30% of subsequent stillbirths (aRR, 36.78 [95% CI, 18.63-72.60]) and more than half of patients requiring iatrogenic early preterm birth (aRR, 92.11 [95% CI, 64.83-130.87]). The AUC for iatrogenic early preterm birth was 0.90 (95% CI, 0.85-0.94)., Conclusions and Relevance: These findings suggest that low PlGF level (<100 pg/mL), identified at the time of routine gestational diabetes screening, may be a powerful clinical tool to identify pregnant people at risk of early preterm birth, especially in iatrogenic births. Strategic redirection of tertiary health care resources to this high-risk group could improve maternal and perinatal outcomes.

Importance: There are limited high-quality, population-level data about the effect of SARS-CoV-2 infection on pregnancy using contemporaneous comparator cohorts., Objectives: To describe maternal and perinatal outcomes associated with SARS-CoV-2 infection in pregnancy and to assess variables associated with severe disease in the pregnant population., Design, Setting, and Participants: CANCOVID-Preg is an observational surveillance program for SARS-CoV-2-affected pregnancies in Canada. This analysis presents exploratory, population-level data from 6 Canadian provinces for the period of March 1, 2020, to October 31, 2021. A total of 6012 pregnant persons with a positive SARS-CoV-2 polymerase chain reaction test result at any time in pregnancy (primarily due to symptomatic presentation) were included and compared with 2 contemporaneous groups including age-matched female individuals with SARS-CoV-2 and unaffected pregnant persons from the pandemic time period., Exposure: SARS-CoV-2 infection during pregnancy. Incident infections in pregnancy were reported to CANCOVID-Preg by participating provinces/territories., Main Outcomes and Measures: Maternal and perinatal outcomes associated with SARS-CoV-2 infection as well as risk factors for severe disease (ie, disease requiring hospitalization, admission to an intensive care unit/critical care unit, and/or oxygen therapy)., Results: Among 6012 pregnant individuals with SARS-CoV-2 in Canada (median age, 31 [IQR, 28-35] years), the greatest proportion of cases were diagnosed at 28 to 37 weeks' gestation (35.7%). Non-White individuals were disproportionately represented. Being pregnant was associated with a significantly increased risk of SARS-CoV-2-related hospitalization compared with SARS-CoV-2 cases among all women aged 20 to 49 years in the general population of Canada (7.75% vs 2.93%; relative risk, 2.65 [95% CI, 2.41-2.88]) as well as an increased risk of intensive care unit/critical care unit admission (2.01% vs 0.37%; relative risk, 5.46 [95% CI, 4.50-6.53]). Increasing age, preexisting hypertension, and greater gestational age at diagnosis were significantly associated with worse maternal outcomes. The risk of preterm birth was significantly elevated among SARS-CoV-2-affected pregnancies (11.05% vs 6.76%; relative risk, 1.63 [95% CI, 1.52-1.76]), even in cases of milder disease not requiring hospitalization, compared with unaffected pregnancies during the same time period., Conclusions and Relevance: In this exploratory surveillance study conducted in Canada from March 2020 to October 2021, SARS-CoV-2 infection during pregnancy was significantly associated with increased risk of adverse maternal outcomes and preterm birth.