3.5. Risk of publication bias
The funnel plots of fever, cough, positive CT findings and coexisting disorders are symmetric, which meant that these indicators may not be published biased. On the contrary, the funnel plots of severe case or death, lymphopenia, preterm labor, cesarean section, fetal distress, neonatal asphyxia or neonatal death or stillbirth and neonatal infection are asymmetric, which meant that the indicators above may have publication bias. Since there was only 1 article about SARS-CoV-2 test of breast milk, it was meaningless to draw a funnel plot. Therefore, the publication bias of it was not evaluated. The funnel plots of fever and cough are shown in Figure S1 and Figure S2.