Strengths and limitations
One of the strengths of our study is that it was designed as a prospective cohort study, while most of the previous studies were case reports and series and a few studies had a retrospective case-control design.The other strength of our study was that we didn’t consider only women who had positive COVID-19 PCR test as a confirmed group, but given the probability of false negative results in the virus PCR,those who had positive CT scan findings in the presence of very typical clinical symptoms were also considered as confirmed infected people, so in this way, we tried not to overlook the infected women as much as possible.As we explained in method section, one of the strengths of our study was choosing very precise exclusion criteria for all three groups, especially for the control group.
One of the limitations of our study is that there is no universal screening for all pregnant women in our hospital, so it is highly likely for some asymptomatic infected women to be found among non -infected group.To overcome this limitation, we have made our best effort to select non-infected women very meticulously as we described in method section. Another limitation of the study, however, was the short duration of the study. Although the sample size of our study is higher than most of previous studies on covid-19 and pregnancy, we believed that If we continued to study, we could increase the sample size, but given the current outbreak of the virus worldwide, we prefered to present our data as soon as possible in order to amass accurate data in this field.