Risk factors for severe disease and impact of severity on pregnant women with COVID-19: a case–control study based on data from a nationwide survey of maternity services in Japan

Abstract

ObjectiveTo identify independent risk factors for severe COVID-19 in pregnant women and to evaluate the impact of disease severity on preterm birth.DesignA case–control study based on data from a nationwide questionnaire-based survey of maternity services in Japan.SettingA questionnaire was mailed to all 2135 delivery institutions in Japan between July and August 2021. A total of 1288 institutions responded (60% of all delivery institutions in Japan). 566 facilities reported having cared for pregnant women with COVID-19, and 722 facilities reported having had no such patients.ParticipantsOne thousand and forty-three hospitalised and non-hospitalised pregnant women diagnosed with COVID-19 between July 2020 and 30 June 2021.Primary and secondary outcome measuresThe primary outcome was progression to severe COVID-19. The secondary outcome was preterm birth due to COVID-19 infection.Results56 cases (5.4%) were severe, and 987 (94.6%) were non-severe. Multivariable logistic regression analysis showed that gestational age≥24 weeks (adjusted OR (aOR) 6.68, 95% CI 2.8 to 16.0) and maternal age≥32 years (aOR 2.40, 95% CI 1.3 to 4.3) were independently associated with severe cases. Using the Kaplan-Meier method, the probability of continued pregnancy at 14 days after diagnosis for severe cases was 0.57 between 24 and 31 weeks’ gestation and 0.27 between 32 and 36 weeks’ gestation. The probability for non-severe cases was 1.0 between 24 and 31 weeks’ gestation and 0.8 between 32 and 36 weeks’ gestation. Among the patients with COVID-19 in the preterm period, preterm birth due to infection was significantly more common in severe than non-severe cases (48% vs 6%, p< 0.0001).ConclusionsSevere COVID-19 in pregnant women was associated with gestational age≥24 weeks and maternal age≥32. The rate of preterm delivery due to the infection was significantly higher in severe COVID-19 cases.

A retrospective observational study on maternal and neonatal outcomes of COVID-19: Does the mild SARS-CoV-2 infection affect the outcome?

“…The majority of pregnant women with COVID-19 were either asymptomatic or experienced mild symptoms (97.4%), while only eight cases (2.6%) were classified as moderate to severe. Consistently, multiple studies during the same period reported that mild cases accounted for 79.8% to 94.6% among pregnant women with SARS-CoV-2 infection ( Arakaki et al, 2022 ; Kumari, Anand & Vidyarthi, 2022 ; Samadi et al, 2021 ). The most common symptoms observed in SARS-CoV-2-infected pregnant women were influenza-like symptoms (including fever, cough, and sore throat), myalgia, and fatigue, which is consistent with observations made by Samadi et al (2021) .…”

“…Furthermore, maternal infection may increase the likelihood of adverse outcomes in neonates through vertical transmission ( Adhikari et al, 2022 ; Kotlyar et al, 2021 ). Recent investigations have reported that a significant proportion of infected pregnant women, ranging from approximately 79.8% to 94.6%, experience mild to moderate symptoms of COVID-19, while approximately 1.99% to 16.7% develop severe disease ( Arakaki et al, 2022 ; Kumari, Anand & Vidyarthi, 2022 ; Samadi et al, 2021 ). Additionally, several studies have shown an increased hospitalization rate and a higher incidence of preterm births associated with COVID-19 in pregnant women compared to non-pregnant individuals ( Ellington et al, 2020 ; Sutton et al, 2020 ).…”

“…In the field of gynecology and obstetrics, the impact of COVID-19 on the well-being of pregnant women and their neonates remains a pressing concern, even in cases of mild infections. The scarcity of comprehensive information and evidence regarding the clinical manifestations and complications of COVID-19 during pregnancy represents a significant knowledge gap, partly attributable in part to the regional and racial disparities observed in previous epidemiological investigations of COVID-19 ( Adhikari et al, 2022 ; Arakaki et al, 2022 ; Kumar, Verma & Mysorekar, 2023 ; Samadi et al, 2021 ). Therefore, the objective of this study is to assess the clinical characteristics, as well as maternal and infant outcomes, of pregnancies affected by SARS-CoV-2 infection within the population of southern China.…”

The COVID-19 pandemic affects pregnancy complications and delivery outcomes in Japan: a large-scale nationwide population-based longitudinal study

“…For COVID-19-infected pregnancy, a report from 60% of all delivery institutions in Japan showed that severe COVID-19 in pregnant women was associated with increased preterm births 19 . Additionally, cumulative evidence indicates that COVID-19 increases the risk of pregnancy complications such as pre-eclampsia, preterm birth, stillbirth, and low birth weight 20 .…”

“…However, the number of pregnant women infected during the pandemic is small. In Japan, 1043 pregnant women had COVID-19 infection between July 2020 and June, 2021, and 5.4% of them www.nature.com/scientificreports/ had severe disease 19 . Therefore, COVID-19 alone may not be sufficient to explain the increased adverse outcomes.…”