Vertical Transplacental Infections

Excerpt

As opposed to horizontal transmission between individuals in a population, vertical transmission of an infectious agent is generally defined as transmission from a pregnant individual to their fetus. Horizontal transmission during pregnancy is frequently examined based on timing (antenatal, perinatal, or postnatal); more specific considerations involve viral transplacental infections. Vertical antenatal and in-utero infections refer to the same general mechanism of infection, although the particular pathophysiologic mechanisms will vary with the infectious agent. Viral transplacental infections represent a critical category of maternal-fetal health concerns, with the capacity to traverse the placental barrier and adversely affect the developing fetus, leading to a range of outcomes, from mild disease to severe congenital anomalies or fetal death.

Infectious agents that can cross the placenta include those historically described by "ToRCHes" (toxoplasmosis, other [hepatitis B virus and syphilis], rubella, cytomegalovirus, and herpes simplex virus). However, Listeria, human immunodeficiency virus (HIV), parvovirus B19, varicella-zoster virus, hepatitis C virus, and Zika virus are also known to cause transplacental infections. Each infection can have profound implications for fetal development, with risks varying based on the timing of infection during pregnancy and the specific pathogen involved. See StatPearls' companion references, " Antepartum infections," "HIV in Pregnancy," and "Pregnancy and Viral Hepatitis," for more information on vertically transmitted infections and associated intrapartum issues.

Please note that the terms "maternal" and "mother" in this activity refer to the birthing parent and are not meant to exclude other birthing parents.