Hematologic Adaptation To Mask-Wearing Among Pregnant Women And Obstetrical Outcome During The Coronavirus Disease 2019 Pandemic

Objective To evaluate the effect of the coronavirus disease 2019 (COVID-19) mask-wearing on hematological laboratory components and obstetrical outcomes among women delivering during the COVID-19 pandemic.Methods Laboratory results and obstetrical outcomes of women with singleton gestations, admitted for delivery during the COVID-19 mask-wearing period (April-June 2020) were compared with those of women delivering during the parallel period in 2019 and with a larger cohort derived from nine pre-pandemic years (March 2011-April 2020).Results Overall, 1838 women delivered during the COVID-19 pandemic. Compared with the pre-pandemic period, mean hemoglobin and fibrinogen levels were significantly higher during the mask-wearing period (12.15 +/- 1.1 vs 11.96 +/- 1.2, P < 0.001 and 472 +/- 103.6 vs 448 +/- 85.1 mg/dl, P < 0.001, respectively). Platelet levels were lower (200 +/- 56.0 vs 206 +/- 57.5 K/mu l, P < 0.001). The rate of delivery at <34 weeks of gestation was lower during the mask-wearing period (1.1% vs 2%, odds ratio [OR] 0.57, 95% confidence intervals [CI] 0.37-0.88, P = 0.01), whereas cesarean delivery and postpartum hemorrhage rates were higher (26.7% vs 24.4%, OR 1.13, 95% CI 1.02-1.25, P = 0.022 and 4.1% vs 2.8%, OR 1.5, 95% CI 1.2-1.8, P = 0.001, respectively).Conclusion A hard-to-ventilate space created by wearing a mask during the COVID-19 era may be the underlying cause of the observed higher hemoglobin level among pregnant women, possibly affecting obstetrical outcomes.