Strengths and Limitations
The main strength of the study is the number of registered cases (403 deliveries from 70 centers across Spain), being one of the largest cohorts described. Furthermore, it represents a novel topic because, to our knowledge, there are no studies that have analyzed perinatal outcomes in neonates born to mothers with COVID-19 regarding the timing of cordon clamping, or that have evaluated the safety of DCC, skin-to-skin contact, and breastfeeding practices in these neonates.
On the other hand, our study has several limitations. Routine serology tests (for determining the immunological state after delivery) were not performed in neonates born to mothers with confirmed COVID-19 due to the lack of availability at the beginning of the pandemic in Spain, and later, once they were available, due to the diversity of tests and protocols in the distinct centers. Furthermore, the clinical questionnaire (for evaluating the neonatal symptoms) was not normalized and homogeneous in all the centers. The determination of parts of the virus in the neonate with ultrasensitive tests does not mean the existence of the complete virus with infective capacity. We did not know if the healthcare professionals who assisted the deliveries or the relatives who visited the neonates were SARS-CoV-2 positive or not. We were able to trace this association in one of the positive PCR cases; nevertheless, in a pandemic like this, we do believe that the present results are unique and relevant because of the difficult circumstances in which they were obtained. In the future, once serologic diagnostic methods improve and become more available, there will be a need to determine the presence and evolution of immunoglobulins against SARS-CoV-2 in order to clarify whether transplacental transmission does exist. Further long-term, prospective studies with neonates are thus required.