Interpretation
In this study, we have tried to address some issues including: the severity of Covid-19 virus infection in pregnancy, the risk of virus infection with pregnancy progress, the virus impact on pregnancy outcomes, delivery type, the possibility of vertical transmission and neonatal consequences.
Studies to date have shown that Covid-19 virus infection is not more severe in pregnant women.(9-12). We also did not have any severe case of corona virus during our study.However, it should be noted that our study was performed only during 50 days and therefore, the absence of a critically ill patient during this period cannot be generally attributed to all pregnancies. In late February 2020, a very ill 22-year-old pregnant woman with no underlying disease who had been infected by Covid-19 virus was referred to our hospital at 37 gestational weeks due of fever and severe shortness of breathing that had started ten days earlier. She developed lymphopenia, thrombocytopenia and low O2 saturation (60%) and unfortunately passed away within 7 hours of admission. Since this happened before beginning of our cohort study, we did not include her in this study.Recently, Hantoushzadeet al. has reported nine pregnant women with severe Covid-19 disease which 7 of them died(13). Their study is a multidisciplinary study that has selected highly ill patients from different centers across Iran, alongside non-random selection bias. However, since no cases of Covid-19 death have been reported in pregnancy so far, their study could make an important change in available evidence about the manifestation of the virus in pregnancy.
Most of the Covid-19 infected pregnant women that have been reported so far were in the third and late second trimesters.(10, 14, 15).In our study,88.3% of those surveyed were in the third trimester of pregnancy. Really, the possibility of picking up infected women based on careful examination and history at earlier ages of pregnancy is lower because of the less routine prenatal visits in first and second trimesters. On the other hand, given the general policies around the world regarding home quarantine during a virus pandemic, pregnant women may not go to medical centers even if there are mild symptoms. So we believe that previous reports including our study might be influenced by these factors and the higher average gestational age in our patients should be interpreted with caution.
In our study, there was no increase in adverse pregnancy outcomes including PTL,GDM, preeclampsia, IUGR, PROM, stillbirth, postpartum haemorrhage and postpartum infection. Most previous studies including a review article(16)also had the same results. Since in most previous studies no comparison has been made between infected and non-infected individuals duo to their methodology, it is not possible to give a definite opinion about the effect of this virus on pregnancy outcomes based on the available data and it demands more prospective studies.
Our results showed that CS rate was not different in the studied groups, but in the majority of previous studies, it was rather higher in infected people(10, 14, 16-18). In a review study, fetal distress was reported to be the most common cause of CS in infected women(17).However, In our study, the most common cause of CS was a history of previous CS.
In our study, only one infant had a positive Covid-19 PCR test after birth that it cannot be definitively related to vertical transmission. Although no decisive vertical transmission of the virus has been reported so far,there area few reports of covid-19 viral pneumonia in 3 infants(19),elevated SARS-Cov-2 IgM and IgG levels in 2 hours after birth in a newborn(20)and a newborn whose nasopharyngeal culture was positive for covid-19 virus 16 hours after birth(21).
Since several factors may play some roles in the vertical transmission, we recommend culture of amniotic fluid, umbilical cord blood and neonatal nasopharyngeal swab at the time of delivery in order to accurately determine the vertical transmission.
Several studies have reported neonatal complications in some of their neonates(10, 19, 22), whereas in some other studies, no neonatal complication has been observed (14, 23).The prevalence of neonatal complications was not different between groups in our study. Nevertheless, we have the impression that maternal condition during peak of the disease may lead to severe transient placental insufficiency. We suggest evaluating uterine and umbilical vessels doppler at the onset and peak of the disease and also after the mother’s recovery and comparing them with neonatal outcomes in futures studies.