There are no undivided opinions on the importance of staying healthy during pregnancy, and every pregnant woman takes utmost care to keep herself and her foetus healthy and free from any infections. Despite taking all the precautions, a pregnant person assigned female at birth (AFAB) is more prone to bacterial and viral infections because of their lowered immunity. Certain viral infections can pose significant risks to both mother and baby. Viral infections during pregnancy can lead to complications. However, with the right knowledge and precautions, many of these risks can be managed effectively. In this article, we will explore the various viral infections that can occur during pregnancy, their potential impacts on both mother and baby and practical tips on how to protect yourself and your unborn child. 

Introduction

There are a plethora of viral infections that affect the human body. While it’s crucial to keep yourself healthy and free of any infections, it becomes even more important to do so during pregnancy. Some of the viral infections are harmless, but the viruses that can cross the maternal-foetal interface or the placental barrier cause severe birth defects. They result in complications ranging from spontaneous abortions and growth restrictions to preterm birth. Various studies have proved that viral infections of the placenta affect foetal development negatively. 

Cytomegalovirus (CMV) has been identified as the most common virus to be present at the maternal-foetal interface, followed by the herpes simplex virus (HSV, see below). They both belong to the Herpesviridae family.¹

Let’s take a look at the most common viral infections in pregnancy and how they affect the well-being of the mother and foetus.

Common viral infections during pregnancy

Influenza

This is commonly known as the flu virus. Symptoms of influenza include cough, fever, runny nose, malaise, headache, chills and sore throat. Pregnancy renders women more susceptible to infection with this virus and even postpartum women are commonly affected by it. Various studies have suggested that infants born to mothers who have been affected by the influenza virus during pregnancy have a greater chance of birth defects.

This virus can easily spread from an infected person when they sneeze, cough, or even speak as it spreads through the air. Pregnant women are prone to seasonal influenza as well as in a pandemic. Spontaneous abortion, preterm birth, birth defects, and foetal death are some of the adverse effects of influenza virus infection. 

All pregnant women should receive the influenza vaccine, which can be taken in any trimester, but it's advisable to take it as early as possible. Effects of the infection can be minimised by taking appropriate medication.² 

Rubella

Rubella or German measles is a self-resolving disease characterised by a rash and is transmitted through respiratory droplets. Maternal rubella infection in the first trimester is far more dangerous than those occurring in the second and third trimesters. 

Rubella is characterised by mild flu-like symptoms, which follow a pink or red rash starting on the face and spreading to the rest of the body. It also includes symptoms like headache, loss of appetite, sore throat, cough, and joint pains. 

Rubella infection during pregnancy, especially during the first trimester, is dangerous as the mother can pass the virus to her foetus. It causes congenital rubella syndrome (CRS) in which the baby is born with birth defects like heart problems, deafness, learning difficulty, deafness, vision problems, low birth weight and organ damage. There is no cure for CRS and the only means to prevent it is a maternal vaccine for rubella. Other risks related to rubella infection include stillbirth, miscarriage and preterm birth. 

The incidence of rubella infection (the number of new cases in a given year) has greatly reduced after the development of the rubella vaccine. If a woman is unsure about receiving the vaccine, a blood test can be ordered to test for circulating antibodies. If no circulating antibodies are found, then the MMR vaccine should be taken right away. This vaccine can not be taken when pregnant. If a pregnant woman finds out she isn’t vaccinated for rubella, then she should stay away from anyone who could be a potential source of infection, i.e., presents with a rash or associated symptoms and also inform the doctor if any such encounter exists.³ 

Cytomegalovirus

Cytomegalovirus (CMV) is a common virus that affects the majority of adults. Once infected, it stays in the body and reactivates, causing another infection. Symptoms of CMV are similar to most viral infections, like chills, fatigue, fever, loss of appetite, headache and sore throat. CMV can be transmitted from person to person by coming in contact with body secretions like blood, saliva, breast milk, urine, semen, cervical and vaginal secretions. 

A pregnant woman can pass CMV infection to the foetus either through the placenta, through vaginal secretions during birth or postpartum during breastfeeding. CMV infection in utero can cause the following defects:

• Congenital hearing loss (most common cause)
• Intellectual disability
• Small size of the head or microcephaly
• Vision loss
• Seizures

Full-term healthy babies are least likely to present with any serious effects of CMV infection if it is acquired during birth. CMV infection can be diagnosed using a blood test.⁴

Herpes simplex virus (HSV)

Herpes simplex virus (HSV) belongs to the Herpesviridae family and is transmitted through mucosal membranes and non-intact skin. It is of two types, HSV I and HSV II, which generally cause oral and genital lesions, respectively. Partner history for HSV infection should be investigated in the first prenatal visit itself. If any positive history of herpes infection is found, then the pregnant female must be advised against any oral or sexual intercourse if recurrence occurs. 

It is important to differentiate between congenital and neonatal herpes infection. Out of these congenital infections are rare, but neonatal infections can occur during pregnancy, during birth or even after birth. There is an increased risk of intrauterine infections in the first 20 weeks of pregnancy. There are more chances of neonatal infection in babies born to mothers with primary HSV infection as compared to those born to mothers having recurrent infections. The risk of infection is higher when the first infection appears in the third trimester of pregnancy. This occurs because maternal antibodies are not formed, leading to more chances of neonatal infection. 

In the event of absent clinical lesions but positive viral cultures at the time of delivery, a caesarean section is recommended. ⁵

Varicella zoster virus (chickenpox)

Varicella or chickenpox is the primary disease of the Varicella zoster virus, which upon reactivation causes herpes zoster in adults. Varicella is mainly a disease of childhood, thus, the majority of women are immune to it before they become pregnant. In cases where primary varicella infection occurs during pregnancy, it is associated with increased risk and fatality. Limb hypoplasia, microcephaly, hydrocephalus, intrauterine growth restriction, cataract, and mental impairment are the hallmarks of this condition. Congenital Varicella syndrome can occur as a result of the reactivation of the Varicella virus in utero. Treatment is mainly aimed at decreasing complications of varicella infection in mothers.⁶ 

HIV

Human immunodeficiency virus (HIV) infection in pregnancy includes a risk of transmission to the foetus. It can occur in utero, during birth, or even during breastfeeding. Because of the high maternal viral load, there is a greatest risk of transmission when the mother has an advanced-stage disease. The mother-to-infant transmission rate has dropped as a result of widespread prenatal HIV testing, counselling, maternal antiretroviral therapy, and neonatal post-exposure prophylaxis for infants of HIV-positive mothers. Other preventive measures include caesarean delivery before labour begins and discouraging nursing.⁷

Hepatitis 

Viral hepatitis is a frequent cause of jaundice in pregnancy, but most infections don’t significantly impact pregnancy. Hepatitis A is usually mild, rarely transmitted to the baby, and is managed with rest and supportive care. Hepatitis B, the most common form of chronic hepatitis globally, poses a greater risk of passing to the baby if the mother has a high viral load, but screening during pregnancy and giving the baby hepatitis B immunoglobulin and vaccines at birth reduce the risk. Hepatitis C has a low risk of transmission to the baby, but the risk increases if the mother is co-infected with HIV. Chronic hepatitis C can lead to serious liver issues later in life, like cirrhosis or liver cancer. Hepatitis E, often seen in developing countries, is more dangerous, especially in the third trimester, with high risks of severe disease, preterm delivery, and even maternal or infant death. Monitoring liver health, avoiding invasive procedures during labour, and good prenatal care are key to managing these infections.⁸

Effects of viral infections on pregnancy

Viral infections in pregnancy pose risks to both the mother and foetus.⁹ 

Maternal health risks

• Weakened immune response: pregnancy alters the immune system, making expectant mothers more vulnerable to viral infections
• Severe illness: Some viral infections can lead to more severe symptoms in pregnant women, potentially requiring hospitalisation or intensive care. For example, influenza or COVID-19 can increase the risk of complications like pneumonia or respiratory distress
• Exacerbation of pre-existing conditions: Viral infections may worsen chronic conditions such as asthma or diabetes, which complicates pregnancy management

Foetal developmental risks

Different types of viral infections can present with varying complications, including:

• Hearing loss
• Developmental delays
• Vision problems in the newborn
• Heart defects
• Deafness
• Cataracts
• Intellectual disabilities

Summary

The ways in which viral infections harm pregnant women and their babies are complex and depend on several factors, such as how contagious the virus is, which tissues or cells it targets, and how the body’s defences, interact with the virus in the placenta. More research is needed to understand how the changes in a woman's body during pregnancy make her more vulnerable to certain viral infections. By studying the causes of viral infections during pregnancy, we can better prepare to deal with new viral outbreaks that may cause complications for both mothers and babies. It's also important to focus on developing antiviral treatments and vaccines that are safe and effective for pregnant women, as this will be a crucial tool in fighting future epidemics and pandemics.

FAQs

Can viral infection in pregnancy cause birth defects?

Yes, viral infections can cause birth defects like hearing loss, vision problems, heart defects, and developmental delays.

How to get rid of a viral infection while pregnant?

It would depend on the type of infection, but a common flu or cold can be managed by gargling warm salt water and ensuring you get plenty of restful sleep. Sip honey mixed in hot water for relief, and stay well hydrated throughout the day. Nasal saline sprays can help with congestion, and using a humidifier can add moisture to the air, making breathing easier.

Which viral infection can cause miscarriage?

Rubella (German measles), cytomegalovirus (CMV), bacterial vaginosis, HIV, chlamydia, gonorrhoea, syphilis, and malaria are all infections that may increase the risk of miscarriage.