Infectious Diseases during Pregnancy - Risks to baby

Infections during pregnancy can be spread to unborn babies

Pregnant woman and doctor

The excitement of a new life inside of a growing belly gives expectant mothers a natural maternal instinct to protect and provide for her baby. Pregnant women undergo emotions ranging from elation to paranoia about their babies’ well-being. In some cases, maternal hormones can be responsible for these mood swings. But it is also important to remember that pregnancies are accompanied by weakened immune systems that can heighten the risk for several infectious diseases.

This can include some common infections - like CMV - and some infections that are in the news, like Zika. CMV, in particular, is incredibly common.

Why Are High-Risk Infections During Pregnancy?

A growing fetus can be thought of as a foreign object that the body accepts by lowering its immunity against it. A normal, active immune system recognizes foreign objects and mounts immune attacks against them. When that foreign object is a fetus, a self-programmed weakening of the immune system, or “immunosuppression,” is necessary for a successful pregnancy. The danger, however, is that the immunosuppressive effect leaves both the mother and developing fetus susceptible to several infectious diseases and complications that normally do not occur in healthy children. There also can be delays in diagnosing some infections during pregancy, as white counts are elevated, pregnant mothers breathe faster and some discomfort and fatigue may be thought due to pregnancy rather than an infection.

What Are the Risks for the Baby?

”Vertical transmission” is a term that refers to the spread of infections from mother-to-baby. These infections may occur while the fetus is still in the uterus (“in utero”), during labor and delivery, or after delivery (such as while breastfeeding).

The following infections can be spread from mother-to-baby:

Congenital infections (passed in utero)

A congenital infection is an infection that crosses the placenta to infect the fetus. Many infectious microbes can cause congenital infections, leading to problems in fetal development, like even microcephaly or other effects on brain development, or even death

More recently we have learned also of the effects Zika can cause if the infection occurs during pregnancy.

Perinatal infections (during labor and delivery)

Perinatal infections refer to infections that occur as the baby moves through an infected birth canal. These infections can include, but are not limited to, sexually-transmitted diseases. For example, infections can also occur through contamination with fecal matter during delivery.



Examples of perinatal infections are:

There are other infections as well. There may be more that we learn about. However, with the help of health professionals, transmission of these infections can be largely avoided (or the risks reduced). In some cases this may mean treatment; in other cases it may mean changing how the baby is delivered. It's important to talk to a doctor or other healthcare professional about any worrisome symptoms or known infections.

Postnatal infections (after delivery)

Infections spread from mother to baby following delivery are known as “postnatal infections.” These infections can be spread during breastfeeding through infectious microbes found in the mother’s breastmilk. Some examples of postnatal infections are:

  • CMV
  • HIV
  • Group B Strep (GBS)

For both perinatal and postnatal infections, there is the risk that the infections may also be drug resistant. In some settings, this could be because infections were acquired after contact with health facilities, but not always necessarily as there are many other reasons for drug resistance.

What Tests Are Available?

Based on a patient’s medical history, risk factors, and exposure to certain infectious diseases, as well as results from ultrasounds and prenatal visits, your doctor will determine whether or not you need to undergo laboratory screening for certain congenital infections. While several diagnostic tests are available for congenital infections, most obstetricians selectively test their patients based on their evaluation, rather than through routine screening.

During an ultrasound, a good technician will be able to detect abnormalities that may be indicative of a congenital infection. He will look for abnormalities in development, such as the size of the baby, head size, as well as defects or underdevelopment of the heart, limbs, lungs, or abdomen.

After birth, a newborn who is suspected to have a congenital infection will be evaluated by examination of his physical development and through laboratory testing of blood samples for levels of liver proteins, antibodies, platelets, and blood cells. If anomalies are detected, the newborn will likely be tested for the presence of a specific infectious microbe.

If you are pregnant and are concerned about congenital infections, ask your healthcare provider about whether or not you should be tested for infections.

Sources:

CDC http://www.cdc.gov/pregnancy/infections.html

PHE https://www.gov.uk/guidance/infectious-diseases-during-pregnancy-screening-vaccination-and-treatment

Perinatal Chikungunya http://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0002996

Ford-Jones, EL and Ryan, G. Implications for the Fetus of Maternal Infections in Pregnancy. Infectious Diseases, 2nd Edition. Cohen J and Powderly WG, editors. Elsevier Limited. ©2004.

Mims CA, Playfair JH, Roitt, IM, Wakelin D, Williams R, and Anderson RM. Obstetric and Perinatal Infections. Medical Microbiology. Mosby-Year Book Europe Limited. ©1993. pp. 26.1-26.8.

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