Results
Tests were performed from 6th to
19th May 2020, after a decline in the number of daily
cases in Australia. The peak reporting of cases occurred on the
27th of March 2020 with 460 confirmed cases nationally
and 111 cases in Victoria (Figure 1). Overall, 351 women consented
SARS-CoV-2 testing. Of those, 332 (94.6%) were tested in antenatal
clinic for routine screening and 19 (5.4%) were tested in the maternity
ward, birth suite, pregnancy assessment unit, or the COVID-19 screening
clinic due to possible symptoms of COVID-19. One patient (0.3%) in the
routine screening group could not tolerate the test, and therefore 350
patients underwent testing.
The baseline characteristics of the screened population are summarised
in Table 1. The median maternal age of the study population was 32 years
(IQR 28 to 35 years). The median gestational age at testing was 33 weeks
and four days (IQR 28 weeks to 36 weeks and two days), 148 women
(42.2%) were nulliparous and 203 (57.8%) were parous. Ten women
(2.9%) were in the first trimester (less than 14 weeks of gestational
age), 77 (21.9%) were in the second trimester (from 14 to 28 weeks of
gestational age), and 264 (75.2%) were in the third trimester of
pregnancy (gestational age of 28 weeks or more).
In the routine screening group, two women (0.6%) reported possible
COVID-19 symptoms in the days that preceded the test (one reported
headache and one reported rhinorrhea). In the symptomatic group, the
most common symptoms were fever (13, 68.4%), respiratory changes
including cough and dyspnoea (5, 26.3%) and sore throat (4, 21%). No
patients reported recent overseas travel or contact with known infected
persons.
All 350 tests were negative for SARS-CoV-2, including those performed in
women with symptoms. Using the statistical “rule of three” for
approximation of the exact estimation for a binomial distribution with
no events occurrence11, 12, we estimate with 95%
confidence that the true proportion of positive tests in the population
is between 0 and 0.86% (p̂ = 0%, 95% CI 0% to 0.86%).