There are a number of viral, bacterial and parasitic infections that can cause complications during pregnancy, including:

• Chickenpox (varicella). Characterized by an itchy rash and fever, this condition is caused by the varicella-zoster virus. The March of Dimes Birth Defects Foundation estimates that one in 2,000 women will develop chickenpox during pregnancy. When a woman is infected during the first 20 weeks of pregnancy, there is a small risk that the baby will be born with congenital varicella syndrome (a group of birth defects). When infection occurs near the time of delivery, the baby may be born with the infection. Left untreated, the disease can be deadly for an infant. However, most babies are treated rapidly and the disease causes only mild illness. Women who develop the infection have a chance of developing a severe form of pneumonia while pregnant (varicella pneumonia). Women who are not immune (as determined by blood test) and not yet pregnant can receive a vaccination before conceiving. Pregnant women who are not immune and have been in contact with an infected person can receive an injection of VZIG, which can prevent the disease or reduce its severity.
  
  
• Cytomegalovirus. This common viral infection is characterized by high fever, sore throat and swollen lymph glands. A woman infected with the virus during pregnancy can transmit the infection to her baby. According to the March of Dimes, approximately 40,000 babies are born infected with the virus each year. Of these babies, about 8,000 will develop lifelong disabilities. The virus can also cause serious illness and death. 
  
  
• Fifth disease. Also known as erythema infectiosum, the disease is caused by parvovirus B19. An infected woman may have joint pain and swelling, and mild flu-like symptoms. Most babies are not affected when their mothers are infected with the disease during pregnancy. However, when a baby is infected, the virus can affect the baby’s ability to produce red blood cells. This can lead to anemia, heart failure and possibly death.  
  
  
• Influenza. Also known as the flu, influenza is a contagious infection of the nose, throat and lungs caused by viruses. Pregnancy can alter the immune system. As a result, pregnancy increases a woman’s risk of complications from the flu, such as pneumonia.
  
  
• Group B streptococcus (GBS). Also known as group B strep, this infection is caused by bacteria. According to the March of Dimes, between 10 and 30 percent of pregnant women carry the infection, and there is a 1 percent chance of the infection being passed to the fetus. Once infected with GBS, a baby can develop pneumonia, sepsis (blood infection), or meningitis (inflammation of the membranes covering the brain and spinal cord). Babies with GBS can be treated with antibiotics. In most babies, the infection causes no long-term damage, but it can lead to permanent neurologic damage or death. Women can be screened for the infection during the last few weeks of pregnancy. Those who test positive or at high risk may be treated with antibiotics during childbirth.
  
  
• Listeriosis. Caused by the bacterium Listeria monocytogenes, listeriosis is a form of food poisoning commonly found in unpasteurized milk and dairy products, poultry, fish and ready-to-eat meats (e.g., cold cuts). Diagnosed by a blood test, the condition is characterized by flu-like symptoms with fever, muscle ache, chills, nausea and diarrhea. In some patients, the condition may progress to meningitis and blood infection. When it occurs in a pregnant woman, the condition can result in life-threatening complications in the baby including miscarriage or stillbirth. Antibiotics are often given to prevent infection in the baby.
  
  
• Rubella. Also known as German measles, rubella is a contagious viral infection spread through the air or through close contact. According to the March of Dimes, about 25 percent of babies whose mothers are infected with rubella in the first trimester are born with one or more birth defects (congenital rubella syndrome). These birth defects may include eye defects, hearing loss, mental retardation, heart defects and movement disorders. Major outbreaks of rubella are rare in the United States because of widespread use of the rubella vaccine but some women are still susceptible to infection. As a result, pregnant women are usually tested for rubella immunity during an early prenatal visit.
  
  
• Salmonellosis. Caused by the bacteria Salmonella, salmonellosis is a form of food-borne infection commonly found in raw or undercooked meats, unpasteurized dairy products, raw or undercooked eggs and alfalfa sprouts. Common symptoms of the condition include diarrhea, fever and abdominal cramps. In some cases, a pregnant mother can pass the infection to her baby. This can cause diarrhea, fever, and in rare cases, meningitis.
  
  
• Toxoplasmosis. This condition is caused by infection with the parasite Toxoplasma gondii. Pregnant women can contract the infection from ingestion of raw or undercooked meat, improper handling of cat litter, ingesting contaminated soil or, rarely, blood transfusion or organ transplant. According to the March of Dimes, about 400 to 1,000 babies are born with the infection each year in the United States. Once infected, a baby may develop eye infections that cause blindness, hearing loss, learning disabilities, and long-term physical and mental disabilities. Infection of a woman during pregnancy can also result in miscarriage and stillbirth. When a blood test reveals that a pregnant woman is infected, amniocentesis may be ordered to determine if the baby is also infected. When the fetus is not yet infected, antibiotics may be prescribed. Medications are also prescribed to the mother when the fetus is thought to be infected, and to the baby after birth.