INTRODUCTION
The relationship of SARS-CoV-2 and pregnancy has been under study since
the outset of the coronavirus pandemic. Evidence shows that pregnant
women with COVID-19 are at an increased risk of severe pregnancy
complications, including preeclampsia (PE), admission at the intensive
care unit, preterm birth or maternal mortality1.
One of the first studies about COVID-19 and pregnancy, published in
February 2020, suggested an increased PE incidence amongst pregnant
women with COVID-192. This was confirmed in a
systematic review published online in March 2020, where a PE incidence
of 14.6% was observed in pregnant women with
COVID-193, as compared with 2-8% in the general
population4. INTERCOVID, a prospective comparative
study matching pregnant women with and without COVID-19, showed that the
risk of developing PE/eclampsia was almost 4 times greater in women with
COVID-191. Subsequent analysis of the same population
examining PE incidence showed a risk ratio of 1.95 (95%CI:
1.38-2.75)5. Recently, a large meta-analysis that
included 28 studies showed an increased PE incidence risk, with an odds
ratio of 1.62 (95%CI: 1.45-1.82)6.
Different theories have been suggested regarding the association between
PE and COVID-195–9. One of them hypothesises that PE
and COVID-19 are associated due to sharing risk factors for endothelial
damage, such as obesity, hypertension, diabetes and maternal age. In
that case, PE in the preclinical stage could be an additional risk
factor for endothelial damage, thereby increasing the risk of developing
COVID-19, mostly in its severe forms. The question is whether
preexisting endothelial damage due to abnormal trophoblastic invasion
increases the risk of developing COVID-19 and its severity, or whether
the association between both conditions is driven by the fact that
COVID-19 and PE share risk factors increasing the risk of both
conditions. If preexisting endothelial damage due to abnormal
trophoblastic invasion10 makes patients more
vulnerable to COVID-19 (or more likely to develop a severe form of
COVID-19), women with COVID-19 would have lower placental growth factor
(PlGF) levels and increased mean uterine artery pulsatility index
(UtAPI) as compared to the reference population.
The primary aim of this study was to examine baseline risk factors, as
well as biochemical and biophysical markers measured in the
first-trimester combined screening for PE in pregnant women with
COVID-19 versus the general population. The secondary aim was to compare
these baseline characteristics and markers between women with mild and
severe COVID-19.