COVID-19 related maternal mortality cases in associated with Delta and Omicron waves and the role of lung ultrasound

OBJECTIVE: To present coronavirus disease-2019 (COVID-19) related maternal mortality in relation to Delta and Omicron waves and to investigate the role of lung ultrasound (LUS) in estimating mortality. MATERIALS AND METHODS: This retrospective cohort study was conducted in the obstetrics and gynecology clinic of a tertiary pandemic hospital between March 2020 and January 2022. The hospitalized pregnant women with COVID-19 diagnosis and maternal deaths were studied in relation with Delta and Omicron waves. The relationship between LUS scores of hospitalized patients and maternal mortality was explored. RESULTS: Thousand and sixty-five pregnant women were hospitalized because of COVID-19 infection. Fifty-one (4.79%) of these patients had critical sickness, 96 (9.01%) of them had severe illness, 62 (5.82%) of them were admitted to the intensive care unit and 28 (2.63%) of all hospitalized pregnant women had died. Of the 1.065 patients, 783 (73.5%) were hospitalized before the Delta wave and the maternal mortality rate was 1.28% (10/783), 243 (22.8%) were hospitalized during the Delta wave and the maternal mortality rate was 7% (17/243) [relative risk (RR)=5.478, 95% confidence interval (CI) (2.54-11.8), z=4.342, p<0.001]. During the Omicron wave 39 (3.66%) patients were hospitalized and the maternal mortality rate was 2.56% (1/39). Maternal mortality rates, according to LUS scores, were 0.37% (1/273) for LUS 0, 0.72% (2/277) for LUS 1, 2.58% (10/387) for LUS 2 and 11.72% (15/128) for LUS 3 respectively (LUS 3 vs. others; maternal mortality: RR=8.447, 95% CI (4.11-17.34), z=5.814, p<0.0001). There were no vaccinated patients in the study cohort. CONCLUSION: The maternal mortality rate was relatively high, particularly during the Delta wave at our referral center. The Delta wave, delayed vaccination and vaccine hesitancy of pregnant women might have important roles in maternal mortality. Higher LUS scores should warn clinicians of an increased risk of maternal death.