Methods
The ItOSS launched a national population-based cohort study to collect information on all women with a confirmed COVID-19 infection receiving in or outpatient hospital care during pregnancy. A case is defined as a pregnant woman with COVID-19 infection confirmed by reverse transcriptase-polymerase chain reaction (RT-PCR) testing for the SARS-CoV-2 virus, through a nasopharyngeal swab, and/or chest X-ray (RX) or computed tomography (CT) findings, and/or through antibody response from maternal peripheral blood.
The ItOSS relies on a network of trained reference clinicians, covering 91% of the nation’s live births (10). The network was extended to a further seven Regions and two autonomous Provinces to reach nationwide coverage for the present study.
The study core outcomes include COVID-19 pneumonia, invasive respiratory support, ICU admission, women’s severe morbidity and mortality.
A multidisciplinary expert group — including obstetricians and gynaecologists, maternal-foetal medicine specialists, neonatologists, paediatricians, anaesthesiologists, midwives, and infectious disease specialists — revised the data entry form and pre-tested its online version.
The data entry form includes fields relating to women’s socio-demographic characteristics, general and obstetric history, COVID-19 infection diagnosis, treatment and complications. A follow-up analysis will collect information on pregnancy outcomes, mode of delivery and maternal and neonatal outcomes.
The clinicians working in the network maternity units use a secure web-based data collection system to record incident cases. They received a manual for the use of the web-based system and have constant help-desk support.
On enrolment, women receive an informative note describing the study and informed consent to the participation is acquired. The ItOSS sends a weekly email to the contact clinicians of the health care facilities, reminding them to report the new cases. For each notified case, a link is sent for online data entry and a unique identifier code is generated. Assuming that data relating to the reported cases might be missing, a new request will be sent by email and, if further reminders are needed, the contact person will be reached by phone.
In case of maternal death from SARS-CoV-2 infection, the ItOSS maternal mortality surveillance system will allow verification and provide further information. The data are collected and processed by personnel in charge of ensuring confidentiality and security.
Since this is an observational study, the cohort size depends on the incidence of the disease.
The preliminary data analysis focused on descriptive statistics stratified by COVID-19 pneumonia occurrence. Significant differences between the two groups were assessed through the Fisher’s exact test suitable for the analysis of small samples.
All the analyses were performed using the Statistical Package Stata/MP 14.2.
This study has not received any funding and was conducted without patient involvement due to lack of time and funds.