Strengths and limitations
The present study provides novel evidence that women with COVID-19 are
at a higher risk for PE at the first trimester mainly due to maternal
risk factors, which are shared by both conditions. In addition, there
does not seem to be an association between COVID-19 and risk factors for
placental insufficiency. One of the main strengths of this study is the
large number of subjects. Additionally, the first-trimester screening
for PE was routinely performed; therefore, despite this being a
retrospective study, maternal risk factors, PlGF and UtAPI were
prospectively recorded for all patients at the time of the routine
first-trimester scan.
One of the main limitations of this study is its retrospective nature.
Additionally, this study may have a selection bias. On the one hand,
cases in the study group with severe disease might be over-represented,
as our site was a referral hospital for severe COVID-19 with pneumonia
in Catalonia. On the other hand, asymptomatic cases in the study cohort
might also be over-represented, since a RT-PCR was incorporated during
the pandemic as a routine test for all admitted patients.
Another limitation of the study is that the general population used as
the reference group cannot be considered purely a control group due to
the lack of specific information about SARS-CoV-2 infection. For this
reason, some asymptomatic and mild COVID-19 cases might be found in the
reference group. Nevertheless, this might have reduced the chances of
finding differences between groups making our findings even more
meaningful.