Vertical transmission includes transmission of a pathogen from a mother to her fetus or newborn before, during, or immediately after delivery. Transplacental transmission occurs during pregnancy when maternal viremia leads to transmission across the placenta (e.g., Zika virus). Perinatal transmission at the time of delivery can occur when the newborn comes into exposure with maternal bodily fluids during delivery (e.g., as occurs with herpes simplex virus [HSV]), through transmission of infectious virus through the breastmilk (e.g., as occurs with HIV), or other bodily fluids (e.g., as occurs with group B Streptococcus and vaginal fluids,  influenza viruses and respiratory droplets), and some pathogens are transmitted by multiple routes.

In limited recent case series of infants born to mothers with COVID-19 published in the peer-reviewed literature, none of the infants have tested positive for SARS-CoV-2.* Additionally, virus was not detected in samples of amniotic fluid.

Limited information is available about vertical transmission for other coronaviruses (MERS-CoV and SARS-CoV) but vertical transmission has not been reported for these infections.

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