Pregnancy and Infections
Certain infections during early pregnancy can cause birth defects in the fetus.
Rubella (German measles) virus infection during early pregnancy can cause birth defects and even miscarriages. Therefore, women of child bearing age are tested for blood antibodies against this virus. Women lacking rubella virus antibodies are susceptible to rubella infection, and should be vaccinated against this virus. Pregnancy should be avoided for one month after vaccination, due to the theoretical concern that the vaccine virus itself may cause fetal damage.
Toxoplasmosis is a small parasite that is transmitted through cat feces and raw meats, especially pork. Toxoplasmosis, like the rubella virus, can cause severe birth defects if the infection occurs during early pregnancy. Women planning pregnancy should avoid raw meat and avoid handling the cat litter box. Many people have been exposed to toxoplasmosis without even knowing it. As a result, they develop a protective immunity from the "silent" infection. Women who have a blood test that is positive for toxoplasmosis immunity can be reassured that they will not develop toxoplasmosis complications during pregnancy.
Hepatitis B is the only type of hepatitis that is known to affect the newborn infant.
- Female healthcare workers, dental assistants, and others exposed to hepatitis B should receive hepatitis B vaccination to avoid chronic infection by this virus. The majority of hepatitis B virus infections resolve spontaneously without treatment. Patients whose disease resolves completely are no longer contagious. The most common mode of transmission of hepatitis B worldwide is from mother to infant. Hepatitis B is spread predominantly parentally through intimate personal contact and perinatally.
- Approximately 10% of hepatitis B virus infections do not resolve, and become chronic. Patients chronically infected with hepatitis B virus may have no symptoms of liver disease early on, but they remain contagious. Over time, chronic hepatitis B infection can lead to liver cirrhosis and/or liver cancer.
- Women with chronic hepatitis B infection can transmit the virus to their babies at birth. Babies infected are at risk of developing chronic liver disease, liver cirrhosis, and liver cancer in later life. Currently, infants born to mothers infected with the hepatitis B virus are given both the hepatitis B antibodies and hepatitis B vaccinations at birth for protection. Therefore, pregnant women are often tested for signs of hepatitis B infection, even if they do not have any symptoms or knowledge of past infection. The babies of infected mothers detected in this manner would receive special care at (and after) delivery.
Cytomegalovirus (CMV) is a common viral infection worldwide that often does not produce any symptoms. Women who become infected or have a reactivation of a previous infection during pregnancy may pass the infection along to their babies. Congenital CMV infection is the most common congenital viral infection.
- If a woman has CMV during pregnancy, she has a 33% chance of passing it to her baby. CMV is the most common virus passed from mothers to babies during pregnancy. About 1 to 4 percent of women have CMV during pregnancy. Most babies born with CMV don't have health problems caused by the virus, but CMV can cause problems for some. It's more likely to cause problems for the baby if it happens in the early part of pregnancy. A woman can also pass CMV to her baby during labor, birth, and breastfeeding.
- Although the majority of infected infants will not have any symptoms, some can develop hearing, vision, neurological and developmental problems over time. In a few cases, there are symptoms present at birth, which can include premature delivery, being small for gestational age, jaundice, enlarged liver and spleen, microcephaly (small head), seizures, rash, and feeding difficulties.
Genital herpes may also result in the passage of the infection to the infant at the time of delivery. The risk of transmission is increased if the genital lesions are from a herpes virus (HSV) infection acquired during the pregnancy, rather than simply a reactivation of previous disease. HSV infection can have multiple effects in the newborn. Disease may be limited to the eyes, skin and mouth; may be localized to the central nervous system; or may be widespread and involve many organs. Treatment involves administration of antiviral medications to the newborn and supportive care.
Parvovirus B19 is a virus that causes the condition known as Fifth disease, a common mild disease of childhood. Transmission is by droplets in the air (respiratory secretions) or through blood. Pregnant women who have not previously had fifth disease should avoid contact with those who have it because parvovirus B-19 can infect a fetus prior to birth.
- Sixty-five percent of pregnant women in North America have evidence of past infection with parvovirus B-19. The incidence of acute parvovirus B-19 infection in pregnancy is approximately 1% to 2% in endemic periods.
- Parvovirus infection is transmitted across the placenta to the fetus in approximately 30% of pregnant women who contract the infection, with a mean interval of 6 to 7 weeks between maternal exposure and fetal infection. For women who contract parvovirus in the firs trimester, the rate of fetal loss can be as high as 10%. The highest risk is between 9 and 16 weeks of gestation. The risk is reduced in the second trimester, and fetal complications are rare during the last 2 months of pregnancy.
- Although no birth defects have been reported as a result of Fifth disease, it can cause the death of an unborn fetus.
When traveling to a foreign country, it is important to determine what diseases are common, whether vaccines are needed, and whether they are safe during pregnancy.
Human immunodeficiency virus (HIV) infection can be passed from a mother to her baby. The chances of this happening are decreased substantially with certain medication regimens taken during pregnancy. Pregnant women are routinely offered testing for HIV infection. Women with previously undetected infection who are found to have HIV infection can be given special medication to try to protect the baby. At the same time, the medication may benefit the health of the mother herself.
Varicella, or chickenpox, can cause pneumonia or even death in older adults and in pregnant women. Varicella vaccine is available for women who are not immune to chickenpox. Women who had chickenpox in the past do not need a vaccine because they are immune. Women who are not sure if they are immune can receive a blood test to determine immunity status. A vaccine would be given if the blood test showed they were not immune.
Zika virus is a Flavivirus that is related to dengue fever, West Nile, yellow fever, and Japanese encephalitis viruses (Flaviviridae). The virus is primarily transmitted by the bite of a mosquito that carries the virus. The resulting illness lasts a few days to a week and causes symptoms like fever, rash, joint pain, and conjunctivitis (redness of the eyes). While mosquitoes are the main known mode of transmission, transmission of the virus from mother to fetus as well as transmission during sexual intercourse have been reported. The infection may also be spread through transfusion of an infected blood product.
The virus has been traditionally reported in Africa and Indonesia, but it has continued to spread to North and South America, and the infection has been noted to have spread to 30 countries. Including parts of the U.S. The viral infection has been linked to birth defects (mainly small head and small brain size, known as microcephaly as well as some eye defects that may lead to vision loss) in babies whose mothers became infected with Zika virus during their pregnancy.
Zika virus cases were first reported in the Americas during 2015–2016; however, the incidence of Zika virus disease has declined since early 2017. Pregnant women, especially those in the first and early second trimester, in areas where the disease is prevalent should try to avoid any mosquito bites and should not travel to areas with known risk for Zika virus transmission. These areas can be identified on the website of the U.S. Centers for Disease Control and Prevention (CDC). Further, pregnant women with a male partner who has traveled to, or lives in, an area where Zika infection is active should refrain from sex or use condoms during sex until the pregnancy is over.