Methods
We performed a cross-sectional study at Victoria’s largest maternity
service, Monash Health, that provides birthing services across three
hospitals in southeast metropolitan Melbourne, Victoria, Australia.
There are about 10,000 births in the service each year (nearly one in
seven of all Victorian births).
During the two-week period from 6th to
19th May 2020, inclusive, women attending routine
antenatal visits were offered SARS-CoV-2 testing. We also included
pregnant women who had testing in other sectors of the hospital
(maternity ward, birth suite, pregnancy assessment unit, or COVID-19
screening clinic) with possible symptoms of the disease. In the weeks
that preceded routine screening, we had adopted the following strategies
in our three maternity hospitals to reduce exposure of patients,
relatives and staff: a significant number of antenatal consultations
(approximately 60%) were shifted to a telehealth model, with
face-to-face appointments reserved for visits at 28, 36 and 40 weeks of
pregnancy, or when deemed necessary by the attending health
professional; all women were routinely asked about recent travel, known
contacts and the presence of recognised COVID-19 symptoms; if symptoms
were present, women were advised to attend the COVID-19 screening clinic
and not to attend their antenatal appointment; all women attending the
clinic or the hospital had body scanning temperature check on arrival;
no support persons were allowed during clinic consultations or
ultrasound examinations, and only one support person was allowed during
labour and birth; and all health care professionals attending births
wore protective equipment (PPE) after appropriate training.
Combined oropharyngeal and nasopharyngeal swabs were collected as
recommended7 and according to national
guidelines8 using FLOQSwabs® and
transported in UTM medium (Copan, Brescia, Italy) by a trained health
professional (nurse or midwife) wearing appropriate PPE consisting of a
gown, nonsterile gloves, eye protection and a protective mask.
SARS-CoV-2 testing was then performed utilising multiplex-tandem
polymerase chain reaction (PCR, AusDiagnostics, Mascot, Australia), an
assay with demonstrated high sensitivity and specificity
(>99.9%)9.
In the screening period, additional data were collected regarding
maternal age, weight, height, parity, gestational age, recent overseas
travel since the beginning of the pandemic and presence or absence of
COVID-19 symptoms during the week that preceded the test. Gestational
age was calculated according to the first day of the last menstrual
period, or by the sonographic measurement of fetal biometric parameters
when the gestational age given by ultrasound differed from that provided
by the last menstrual period by more than one week.
To evaluate the context in which the tests were performed in the
antenatal clinic, statistics concerning the daily number of cases in
Australia and the state of Victoria were obtained from the Australian
Government Department of Health website10.
The primary outcome of the study was the proportion of pregnant women
with a positive SARS-CoV-2 test. Continuous variables were assessed for
normality by inspection of histograms and quantile-quantile (Q-Q) plots.
Since the distributions of continuous baseline variables were not
Gaussian, metric and ordinal variables were summarised as the median and
interquartile range (IQR). Categorical variables were expressed as
absolute number and percentage. The proportion of positive results was
reported with its 95% confidence interval. Statistical analysis was
performed in Stata version 16.1 (StataCorp. 2019. Stata Statistical
Software: Release 16 for Macintosh. College Station, TX: StataCorp LLC).
Review of the screening results was approved by the local Human Research
Ethics Committee (approval number QA/66029/MonH-2020-219471).