All You Need to Know About Vertical Transmission

By Dr. Gayatri Deshpande in Gynaecology & Obstetrics

Apr 24 , 2023 | 7 min read

What is a Vertical Transmission?

Vertical transmission refers to the transmission of an infectious agent from a parent to their offspring through the placenta, breast milk, or genital tract during delivery. This mode of transmission can occur during pregnancy, birth, or breastfeeding, and can result in a wide range of outcomes depending on the pathogen involved and the timing and severity of the infection. It can occur with a variety of pathogens, including bacteria, viruses, and parasites. 

Some examples of vertically transmitted infections include HIV, hepatitis B and C, rubella, syphilis, and toxoplasmosis. In some cases, the infection may be asymptomatic in the mother but can cause severe illness or even death in the newborn.

Vertical transmission can have long-term consequences for both the mother and the offspring. Infants who are infected during the prenatal or perinatal period may experience developmental delays, hearing or vision loss, or other neurological impairments. In addition, mothers who transmit infections to their infants may experience psychological distress and stigma, as well as an increased risk of future complications in subsequent pregnancies.

Preventing vertical transmission requires early identification and treatment of the infection in the mother, as well as appropriate interventions during delivery and postpartum care. This may include antiviral or antibiotic therapy, scheduled cesarean delivery, and avoiding breastfeeding in certain circumstances.

Types of Vertical Transmission

  • Transplacental transmission: In this type of vertical transmission, the pathogen crosses the placenta and infects the fetus directly.
  • Perinatal transmission: Perinatal transmission occurs during childbirth when the infant comes into contact with infected maternal fluids.
  • Breast milk transmission: Certain infections, such as HIV, can be transmitted through breast milk from mother to child.
  • Intrauterine transmission: Intrauterine transmission occurs when the pathogen infects the fetus before birth, usually through the amniotic fluid.
  • Trans-generational transmission: This type of transmission occurs when the pathogen is passed down through generations of a family. Examples include inherited genetic disorders and infections that can be transmitted from mother to daughter.

Which diseases Can Be Transmitted Vertically?

Vertical transmission can occur for any infectious disease, including bacterial and viral diseases. The most frequently contracted illnesses include:

  • HIV/AIDS: HIV/AIDS is a virus that attacks the body’s immune system, making it more vulnerable to other illnesses. HIV can be passed from mother to fetus during pregnancy, delivery, and through breastfeeding.
  • Syphilis: Syphilis is a bacterial infection that can be passed to a baby in utero or through contact with an infected mother during birth.
  • Rubella: Rubella, or German measles, is a contagious viral infection that can cause severe birth defects and death in newborn babies if the mother is infected with the virus during pregnancy.
  • Cytomegalovirus (CMV): CMV is a common virus that is typically harmless in healthy adults, but it can cause severe illnesses in babies if passed from the mother during pregnancy.
  • Hepatitis B: Hepatitis B is an infectious virus that attacks the liver and can cause serious long-term health problems. If passed from mother to fetus, the virus can be passed through the placenta or during delivery.
  • Herpes: Herpes is an infection caused by a virus, and it can be passed to an infant during birth if the mother is infected with the virus.
  • Zika: Zika is a virus that can cause a range of health problems in a fetus, including microcephaly, when the virus is passed from mother to fetus during pregnancy.
  • Bacterial Infections: Bacterial infections like strep, gonorrhea, and chlamydia can all be passed from mother to fetus or baby. If left untreated, these infections can cause serious long-term health complications.

Vertical Transmission Symptoms

Vertical transmission can lead to a wide range of symptoms in newborns and infants, depending on the infectious agent involved. Here are some common symptoms of vertical transmission:

  • Congenital anomalies: Some infectious agents can cause congenital anomalies in newborns. For example, the rubella virus can cause deafness, cataracts, and heart defects.
  • Respiratory distress: Newborns infected with respiratory syncytial virus (RSV) may experience respiratory distress, including rapid breathing, wheezing, and coughing.
  • Skin rash: Some infectious agents, such as herpes simplex virus (HSV), can cause a skin rash in newborns.
  • Jaundice: Vertical transmission of hepatitis B virus (HBV) can lead to jaundice, a yellowing of the skin and eyes.
  • Enlarged liver or spleen: Some infectious agents, such as cytomegalovirus (CMV), can cause the liver or spleen to become enlarged.
  • Feeding difficulties: Infants infected with human immunodeficiency virus (HIV) may experience feeding difficulties and failure to thrive.
  • Central nervous system abnormalities: Vertical transmission of toxoplasmosis can cause central nervous system abnormalities, such as hydrocephalus and seizures.
  • Low birth weight: Some infectious agents, such as syphilis, can lead to low birth weight and other complications during pregnancy.

It is important to note that not all infants born to mothers with an infectious disease will develop symptoms of vertical transmission. However, early detection and treatment can prevent serious complications and improve outcomes for affected infants.

Vertical Transmission Complications

Vertical transmission, or mother-to-child transmission, of infectious agents, can lead to a variety of complications. These may include:

  • Birth defects: Some infectious agents can cause birth defects, including deafness, blindness, and heart defects.
  • Neurological damage: Certain infections can cause damage to the brain and nervous system, leading to developmental delays and other neurological complications.
  • Organ damage: Infections such as hepatitis B and C can lead to liver damage and cirrhosis.
  • Low birth weight: Infants born to mothers with certain infections may have a low birth weight, which can increase the risk of complications.
  • Increased risk of infection: Infants born to infected mothers may be more susceptible to infections, particularly during the first few months of life.
  • Mortality: In severe cases, vertical transmission can lead to infant death.

Vertical Transmission Treatment and Management

The treatment and management of vertical transmission depend on the infectious agent involved and the severity of the infection in the newborn. Early diagnosis and prompt treatment are crucial to prevent complications and improve outcomes for affected infants.

In cases where the mother is known to be infected with an infectious agent that can be transmitted vertically, healthcare providers may recommend antenatal screening and treatment to reduce the risk of transmission. For example, pregnant women infected with the hepatitis B virus (HBV) may be treated with antiviral medications and their infants may receive hepatitis B immune globulin at birth.

If an infant is born with symptoms of vertical transmission, it may be treated with medications, such as antivirals or antibiotics, to help manage the infection. In cases where the infection is severe, hospitalization may be required.

In addition to medical treatment, parents and caregivers can help to manage vertical transmission by taking precautions such as practicing good hand hygiene, avoiding close contact with others who are sick, and ensuring that the infant receives appropriate vaccinations on schedule. Overall, early detection and prompt treatment can help to prevent complications and improve outcomes for infants affected by vertical transmission.

Strategies to Prevent Vertical Transmission:

  • Safe sex practices: This includes the use of condoms during sexual activity, as many STIs can be transmitted through sexual contact. It is important for pregnant women and their partners to practice safe sex to prevent the transmission of infections that could harm the developing fetus.
  • Vaccination: Many infections can be prevented through vaccination, such as the rubella virus, which can cause birth defects if contracted during pregnancy. Pregnant women should consult with their healthcare providers to ensure that they are up-to-date on all recommended vaccines.
  • Avoiding contact with infected individuals: Pregnant women should avoid contacts with individuals who have active infections, such as chickenpox or measles, as these infections can be dangerous for both the mother and fetus. This may include avoiding travel to areas with high rates of infectious diseases.
  • Treating infections before pregnancy: If a woman has a chronic infection, such as HIV, it is important to receive treatment before becoming pregnant to reduce the risk of vertical transmission. Additionally, if a woman has a history of recurrent genital herpes, antiviral medication may be recommended to prevent outbreaks during pregnancy.

Importance of Pre-Natal Screening:

  • Prenatal screening for infectious diseases is crucial to prevent vertical transmission from mother to baby.
  • Screening can detect various infections that can be transmitted vertically, such as HIV, hepatitis B and C, syphilis, rubella, and toxoplasmosis.
  • Different types of screening tests are available for different infections, such as blood tests, urine tests, and amniocentesis.
  • Blood tests are the most commonly used for prenatal screening, including the HIV test, hepatitis B and C tests, syphilis test, and rubella test.
  • Toxoplasmosis screening may require a combination of blood tests and amniocentesis.
  • Screening should ideally be done before pregnancy or early in pregnancy, as some infections can be more effectively treated or managed if detected early.
  • Screening may also be recommended during pregnancy if the mother is at high risk for certain infections, such as if she has a history of sexually transmitted infections or injection drug use.
  • Treatment or management options may be available for some infections, such as antiretroviral therapy for HIV or antibiotics for syphilis.
  • Early detection and treatment can significantly reduce the risk of vertical transmission and improve the outcomes for both mother and baby.

Vertical Transmission of COVID-19

While vertical transmission of COVID-19 is rare, it can occur in some cases. Studies have shown that the risk of vertical transmission increases in pregnant women who are infected with COVID-19 during their third trimester. Common symptoms of COVID-19 in newborns include respiratory distress, fever, and difficulty feeding. However, most infected newborns have mild or no symptoms and recover quickly. 

To reduce the risk of vertical transmission, pregnant women are advised to take precautions such as wearing masks, practicing good hand hygiene, and avoiding large gatherings. If a pregnant woman tests positive for COVID-19, her healthcare provider may recommend monitoring the pregnancy closely and considering early delivery if the risk of complications is high.