First-Trimester SARS-CoV-2 Infection: Clinical Presentation, Inflammatory Markers, and Obstetric Outcomes.

Objective: Second- and third-trimester SARS-CoV-2 infections may have an increased risk of obstetric complications. However, data on first-trimester infections are scarce. We sought to characterize the clinical and inflammatory presentations and pregnancy outcomes of first-trimester infections.

Methods: A population-based multicenter study including 817 singleton pregnancies with SARS-CoV-2 serologic testing at 8-14 weeks between March and May 2020. Blood count, uterine artery Doppler, and pregnancy-associated plasma protein A (PAPP-A) were performed in all women. Placental growth factor (PlGF), soluble fms-like tyrosine kinase 1 (sFlt-1), IL-6, and ferritin were determined in positive women. Obstetric outcomes were evaluated.

Results: The prevalence of first-trimester infection was 15.2% (n = 124). 72.6% of positive women were asymptomatic. Symptomatic women had higher rates of lymphopenia (1.91 × 109/L vs. 2.16 × 109/L, p = 0.017) and increased levels of IL-6 (9.1% vs. 1.2%, p = 0.051), but lower rates of decreased ferritin (6.3% vs. 19.8%, p = 0.015). PAPP-A was higher in symptomatic women compared with asymptomatic and negative women (1.44 [IQR 0.90-1.82] vs. 1.08 [IQR 0.66-1.61] p = 0.014, vs. 1.08 [IQR 0.77-1.55] p = 0.019, respectively). Obstetric outcomes were not increased.

Conclusions: First-trimester SARS-CoV-2 infections are mostly asymptomatic, with a mild increase of inflammatory markers in symptomatic women. Obstetric complications were not increased, but PAPP-A levels were higher in symptomatic women.