Chickenpox, measles, the flu, and fifth disease during pregnancy

Pregnant women often worry about contracting infections, especially those that tend to affect children and cause rashes (red patches or small blisters). Fortunately, not all contagious diseases are harmful to the pregnant woman and fetus. That said, it’s important to know which ones have a risk of complications so you can take the necessary precautions.

If you feel sick and have symptoms associated with fifth disease, chickenpox, measles, or whooping cough, seek medical attention immediately. Before you arrive, inform the clinic that you may have a contagious disease.

Fifth disease (or erythema infectiosum, or parvovirus B19)

If you’ve previously had fifth disease, your body already has the antibodies to fight it off, which means you and your fetus are protected. This is the case for more than half of all pregnant women in North America.

However, if you aren’t immune and contract fifth disease before your 20th week of pregnancy, you could pass it on to your fetus. The infection can sometimes cause severe anemia in the fetus, which can lead to a miscarriage. After 20 weeks, there is almost no risk of transmission or complications related to fifth disease.

However, it can be difficult to know if you’ve ever had fifth disease, as it sometimes goes unnoticed and can be mistaken for a cold or flu. The only way to find out if you’re immune to the disease is to get a blood test.

Fifth disease mainly affects school-aged children and is usually harmless. Symptoms tend to be mild: fever, cough, runny nose, but especially red cheeks and a rash on the torso, arms, and legs.

If a child in your social circle has fifth disease, contact your prenatal care provider. Depending on your situation, they may want to do a blood test to find out whether you have the antibodies to fight off the infection. If you don’t have the antibodies, they may want to schedule more frequent follow-ups to monitor your fetus.

Chickenpox

Chickenpox is usually harmless in children but can cause complications for both the mother and fetus when contracted during pregnancy. However, pregnant women born in North America are unlikely to get it, as 90 percent are immune to the disease. In addition, pregnant women are less likely to be exposed to chickenpox if the children they’re in contact with have been vaccinated against it.

What should you do if you come in contact with someone who has chickenpox?

• If you’ve already had chickenpox: Don’t worry, the disease won’t affect the development of your fetus.
• If you’ve never had chickenpox or don’t know whether you’ve had it: Contact your doctor within 48 hours of exposure. They’ll check if you’re immune to the disease.
• If you aren’t immune to chickenpox: Your doctor will prescribe a shot of antibodies to reduce the severity of the disease or prevent it altogether.

Depending on your situation, your prenatal care provider may suggest that you get vaccinated for chickenpox after giving birth.

Measles

Measles is a highly contagious but increasingly rare infection. Although generally harmless in children, measles can lead to complications in pregnant women, such as serious illness, miscarriage, premature birth, and low birth weight. To date, no congenital malformations have been associated with measles in pregnant women.

Contact your doctor, your local CLSC, or Info-Santé (811) immediately if you’ve been in contact with someone who has measles. A doctor or nurse will assess whether you have the necessary antibodies to protect you from the infection. If you aren’t immune, a shot of antibodies may be prescribed to prevent the disease or lessen its symptoms. For this shot to be effective, you must get it within 7 days of exposure.

If you get measles while pregnant, speak with a doctor right away. After examining you, they may recommend treatment to lower your fever and limit the risk of complications.

Influenza (flu)

Complications and hospitalizations related to influenza during pregnancy usually happen in the third trimester but can also occur in the second trimester. In addition to being harmful to the pregnant woman’s health, the flu can be transmitted to her newborn baby.

If you’re pregnant, plan to get a flu vaccine in your second trimester (from week 13) to protect you and your fetus. However, if you have a chronic health condition, it’s best to get the shot in your first trimester.

Whooping cough

Whooping cough is a highly contagious infection of the upper respiratory tract caused by Bordetella pertussis bacteria. The disease can be serious in children under a year old, especially in babies under 6 months.

To protect your newborn from whooping cough, you should get vaccinated between weeks 26 and 32 of your pregnancy. The vaccine will immunize you and protect your baby from the infection during their first few months of life. Women should get a whooping cough vaccine during each pregnancy.

Consult a doctor if you were in contact with someone with whooping cough in the 4 weeks before your due date. They may prescribe an antibiotic after evaluating you.

Other contagious diseases

If you’re pregnant, being around someone with a contagious disease isn’t always risky for the fetus. For example, if you’re in contact with someone who has roseola, hand, foot, and mouth disease, or scarlet fever, don’t worry. Your unborn baby is not at risk.

However, if you think you may have contracted one of these contagious diseases, consult a doctor. After diagnosis, they will make recommendations and suggest an appropriate treatment to lower your fever and mitigate any other symptoms.

Scientific review: Lise Ross, nurse, M.Sc., CHUM Birthing Centre. Research and copywriting: The Naître et grandir team Updated: March 2019

Photo: GettyImage/fizkes