Discussion
We here report a 1.1% SARS-CoV-2 prevalence under presumed asymptomatic labouring and hospital admitted pregnant women, taken in a six weeks’ interval that includes the peak incidence in Amsterdam in the end of March, beginning of April. These results are in contrast with other studies where percentages of SARS-CoV-2 in asymptomatic pregnant women were as high as 3-14% [3 4]. Knowing that SARS-CoV-2 PCR testing will not have 100% specificity, there will be false positive test results. Consequently, in our setting PCR helped to increase a pre-test likelihood of not having COVID-19 of 98.9% with an estimated 1 percentage point or less. It is therefore debatable which prevalence rates are high enough to justify a policy of universal PCR testing and full COVID-19 precautions if a patient has not been tested negative for SARS-CoV-2. Given the delay associated with personal protection equipment (PPE) for health care workers, and the potential for foetal damage in obstetric urgencies, these conflicting interests should be weighed carefully. Moreover, most pregnant women will undergo loco-regional anaesthesia rather than aerosolizing general anaesthesia. This further inflates the number of patients that needs to be screened to prevent viral transmission from a patient to a health care worker. Each hospital should therefore weigh the pros and cons of universal screening versus PPE in their own setting and background incidence, to balance the risks for health care workers versus the additional perinatal risk of alternative care processes for unscreened patients in obstetric emergencies.