Interpretation
Common symptoms at onset of COVID-19 of pregnant women were fever, cough and abdominal pain, and the less common symptoms were chills, dyspnoea, chest pain and pharyngalgia. However, some patients presented initially with atypical symptoms, such as diarrhea and rhinobyon. The most significant laboratory abnormalities observed in pregnant group were depressed lymphocytes counts, increased leucocytes and neutrophil counts, and elevated C-reactive protein level compared with those in non-pregnant group (all P < 0.001, Table 2). These abnormalities suggest that SARS-CoV-19 infection in pregnant women may be associated with cellular immune deficiency and inflammation response (may resulted in cytokine storm) induced by virus. Meanwhile, physiological haemodilution in pregnancy lowers the hemoglobin level of pregnant women, as reflected in the difference of hemoglobin level between the two groups. A further drop in hemoglobin level might jeopardise the stressed oxygen carrying capacity of mother, adding further risk to pregnant COVID-19 patients. Additionally, a higher level of lactate dehydrogenase at presentation had been associated with potential severity among pneumonia patients in most7, but not all, case series8. Likewise, a higher lactate dehydrogenase level was found in our pregnant group, reflecting tissue necrosis related to immune hyperactivity in COVID-19. The presence of such adverse outcome predictor may reflect the severity of the disease course in pregnancy.
Currently, the approach to this disease is to control the source of infection; use of personal protection precaution to reduce the risk of transmission; and early diagnosis, isolation, and supportive treatments for affected patients. Until now, no specific treatment has been proven to be effective for coronavirus infection except for meticulous supportive care9. In our study, most pregnant patients were treated with arbidol and oseltamivir (24 of 31 patients, 77.4%). Although arbidol and other antiviral drugs have been used in the clinical treatment of patients with COVID-19, no data of their safety and efficacy as COVID-19 treatments have been published. The experience gained from previous antiviral pneumonia (eg. SARS and MERS) is also limited10-12. More pregnant patients received antibacterial agents and corticosteroids in this study, as compared with non-pregnant patients (all P ≤ 0.001; Table 3 and online supplement, Table S1). Timely use of antibiotics to prevent secondary bacterial infections and strengthen immune support treatment can reduce complications and mortality, so antibiotics were used routinely after operation13. Corticosteroids should not be routinely given systemically, unless for possible benefit by reducing inflammatory-induced lung injury, according to WHO interim guidance14. Additionally, the use of large doses of corticosteroids during pregnancy might lead to fetal malformation in previous study15. Among our two groups of 155 laboratory-confirmed patients with SARS-CoV-19 infection, corticosteroids were given to very few non-pregnant women (16.1%), and low dose of corticosteroids were given to 23 pregnant patients (74.2%, Table 3 and online supplement, Table S1). Thus far, no complications related to the steroids have been recorded in the pregnant women, mothers and neonates in our study. Further evidence is urgently needed to assess their safety. As is known to us, total lung capacity of pregnant women decreases towards term. There is also a decrease in both residual volume and expiratory volume in pregnant women, resulting in a 9.5% to 25% drop in functional residual capacity. Moreover, there is a 20% increase in oxygen demand in pregnancy16. This might explain why more pregnant patients required oxygen support in this study (Table 3).
Because of alterations in hormone levels and decreased lung volumes caused by increases in uterus size during pregnancy, patients might have a more rapid clinical deterioration. In this study, we have presented 31 cases of COVID-19 in pregnancy and 124 control cases with similar outcomes, including 17 newborns with negative COVID-19. There were no ICU admissions and no complications of ARDS, acute renal injury and acute liver injury for all the pregnant throughout the study period. All of the 155 patients have been discharged as of Jul 8, 2020, the hospital stay of pregnant patients was 13 days (IQR, 9.0-24.0). These results are different from those former pneumonias (eg. SARS, MERS, H1N1, et al)17, 18, which stated that infected pregnant patients had wore outcomes. This might be associated with: First, different pathogenicity among these human coronaviruses. For example, the mortality rate of SARS infection is 10%19, and the mortality rate of SARS in pregnant women was 25%20, while the mortality rate of patients with COVID-19 is about 1.4%21. Second, COVID-19 pneumonia in pregnancy is a complicated clinical scenario, a multidisciplinary team of medical personnel from Renmin Hospital of Wuhan University participated in the whole procedure of caring these patients comprehensively and timely (the median durations of pregnant women from illness onset to hospital admission were 5 days). This team, including obstetrics, internal medicine, paediatrics, infectious diseases, anaesthesia, psychology, and infection control, has played a positive role.