4.3. Interpretation
The
subgroup analysis between pregnant women with COVID-19 and nonpregnant
people with COVID-19 showed that the incidences of fever and cough in
pregnant women with COVID-19 (51%, 31%) were lower than that in
ordinary people (91%, 67%), which may due to the changes in the immune
system of pregnant women and further research is needed. A study from
China CDC showed,80.9% of Chinese patients were considered
asymptomatic or mild pneumonia(25).Desmond Sutton et
al. showed that of the 215 pregnant women who gave birth at the New
York–Presbyterian Allen Hospital and Columbia University Irving Medical
Center, 29 (87.9%) of the 33 patients who were positive for Sars-CoV-2
test had no symptoms of COVID-19 at the time of
admission(19).The fact that the asymptomatic rate in
the infected general population in China is lower than in infected
pregnant women in the New York Medical Center seems to support this
conclusion above. It suggested that Sars-CoV-2 test should be universal
in high-risk areas to improve the isolation of asymptomatic infected
individuals. It is different from the fact that pregnant women with
SARS-CoV have worse prognosis than ordinary people with SARS-
CoV(26). It is possible that in pregnant women, the
clinical outcome of COVID-19 infection is better than that of SARS-CoV.
Yan et al. confirmed that the current mortality rate of COVID-19(2%) is
significantly lower than that of SARS (9.6%) , which may indicate that
SARS is more pathogenic and lethal than COVID-19, thus pregnant women
with COVID-19 infection had better outcomes than those with SARS-CoV(27).
However, our finding that pregnancy women with COVID-19 had better
clinical outcomes, might be biased owing to the relatively small sample
included in this meta-analysis.
A
meta-analysis showed that the CT positive rate of covid-19 infection in
the general population was 89.76%(28), which was more
than 71% in this paper. This also corresponded to the conclusion above
that the clinical outcomes of pregnant women with COVID-19 were superior
to general population. The incidence of positive CT findings was the
highest among the symptoms. Shital J. Patel et al. confirmed that chest
CT was considered a low-dose examination provided the fetus was excluded
from the primary beam, and the estimated radiation doses were too low to
induce fetal neurologic deficits during any trimester of
pregnancy(29). It seemed that chest CT was suitable
for routine screening of patients. However, there were a large quantity
of pregnant women with asymptomatic infection
(87.9%)(19). If chest CT is used as routine
screening, it means that almost all pregnant women need it. In addition,
WHO defines screening as the presumptive identification of unrecognized
disease in an apparently healthy, asymptomatic population by means of
tests, examinations or other procedures that can be applied rapidly and
easily to the target population(30).
As
a consequence, it is improper to perform chest CT as a screening tool
for pregnant women with COVID-19. We recommend to use it as the routine
examination for suspected cases.
The rate of preterm labor in normal pregnant women worldwide is about
11% (31), which is lower than the result of this
article (23%). The possible reason is that women in the third trimester
of pregnancy terminate their pregnancy early after being infected with
COVID-19 in order to proceed with further treatment. Most of these women
choose early delivery by cesarean section in order to avoid prolonged
labor which may worse COVID-19 for pregnant women(32)and increased risk of infection for
medical
staff(33). Chen R et al. confirmed that both epidural
anesthesia and general anesthesia were safe and effective for women with
COVID-19 during cesarean section (12).
Due to the P value was greater than 0.05, the rate of neonatal
COVID-19 infection should not be considered. Wang S et al. reported the
first case in China that the mother with COVID-19 gave birth to an
infected baby in February 2, 2020 (34)and the instant
SARS-CoV-2 nucleic acid tests of umbilical cord blood and placenta were
both negative. And there are 3 neonates infected in the included
literature. Khan S. et al reported that the swab samples tested within
24 hours after the delivery were positive in two neonates while
intrauterine tissue samples such as placenta, cord blood or amniotic
fluid were not tested (14). Yu N et al reported that
the nucleic acid test for the throat swab of one neonate was positive at
36 h after birth (22). Without testing the
intrauterine tissue samples, we could not confirm if the COVID-19
infection in the neonate was the result of intrauterine transmission.
Two studies also showed that the test for SARS-CoV-2 specific antibodies
(IgG and IgM) in neonatal serum samples could be evidence of vertical
transmission (35, 36). Other literature revealed that
almost all the other newborns from infected women were tested negative
for SARS-CoV-2(10-13, 15-21, 23, 37-40). Wang C et al
summarized that there was currently no evidence for intrauterine
infection caused by vertical transmission in women with COVID-19 during
the third trimester of pregnancy but it was uncertain whether there
could be a risk of vertical transmission when the COVID-19 infection
occurs in the first or second trimester, or when there was a long
clinical manifestation-to-delivery interval (41). So
we must continue to keep alert.