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What Is Maternal Infection?

Maternal infection and fetal infection occur during pregnancy when the mother’s body is invaded with pathogenic microorganisms. Mild infections are a common complication of the gestation period and typically do not cause serious problems. However, some infections can cause problems for both the developing fetus and the mother. 

Certain microorganisms can harm pregnant women but have no detrimental effect on the fetus, while other microorganisms do not harm the mother but may harm the developing fetus.

A pregnant woman’s body will respond uniquely depending on the type of infection. Viral infections, bacterial infections, parasitic infections, and fungal infections are possible.

Maternal infection during pregnancy can cause the mother or the baby to develop an infectious disease, which could be anything from a common cold to Acquired Immune Deficiency Syndrome (AIDS).

Some women are at higher risk for infection during pregnancy because their immune systems are naturally suppressed. With proper prevention, observation, diagnosis, and treatment of perinatal maternal infections, neonatal morbidity and mortality are reduced.

What types of infections can harm a baby during pregnancy?

From an epidemiological standpoint, various infections can adversely affect pregnant women and their developing fetuses during gestation.

Group B Streptococci Infection ​

Group B streptococci is a gram-positive bacteria typically found in the vagina or rectum. It is a common bacteria in women and usually causes no problems. However, overproliferation of this potentially disease-causing microorganism may result in sepsis in the fetus.

Herpes Simplex Virus

This viral infection typically manifests in either the birth canal or the vagina. If the herpes simplex virus develops in the birth canal, the baby may contract it during delivery.


According to a study published in Nature Reviews Microbiology “[m]ore than 50% of women with syphilis have adverse pregnancy outcomes, and fetal transmission causes a wide variety of neonatal pathologies including meningitis, osteochondritis, bone marrow suppression and hydrops.” Congenital syphilis causes an estimated 100,000 infections in infants each year. This sexually transmitted disease, which is responsible for 150,000 stillbirths and 60,000 neonatal deaths annually, can be avoided by practicing safe sex and maintaining good hygiene.


As its name suggests, hepatitis affects hepatic functioning in the liver. This virus may be transmitted via sexual contact, oral contact, or contact with infected blood.


Toxoplasmosis is an infection resulting from contact with a parasite found in cat feces. However, it may also be present in undercooked meat, non-potable water, soil, and other sources.


This viral infection typically causes fatigue, sore throat, fever, and body pain.


This sexually transmitted disease is a common bacterial infection that typically affects the rectum, throat, and urethra. It can cause various adverse neonatal outcomes.


This rare bacterial infection affects the upper respiratory tract and can progress into the brain. Pregnant women with meningitis face an increased risk of death and stillbirth.

What are the risk factors for maternal infection?

According to NICHD, some factors increase a pregnant woman’s risk for maternal infection, morbidity, and mortality. Steps can be taken to lower certain risk factors, but not all can be prevented.

Some risk factors that increase a woman’s chances of contracting a maternal infection include:

  • Pre-pregnancy medical conditions like obesity, heart disease, and poor immunity
  • Pregnancy complications like preeclampsia, high blood pressure, and blood clots
  • Being pregnant with twins or triplets
  • Poor health habits, such as smoking
  • Being over 40 years old
  • Gestational diabetes

Some women experience maternal infection, maternal morbidity, and death without displaying any known risk factors.

What are the symptoms of maternal infection?

The symptoms of maternal infection will depend on which microorganism is attacking the mother. Some obstetric infections may have no obvious symptoms. And sometimes, one infection will display symptoms associated with another infection, making it difficult for health-care providers to properly diagnose.

Common symptoms of maternal infection include:

  • Diarrhea
  • Sore throat
  • Mouth sores
  • Stiff neck muscles
  • Shortness of breath
  • Nausea and vomiting
  • Fever, chills, and sweats
  • Congested nasal cavities
  • Abnormal vaginal discharge
  • Inflammation in any part of the body
  • Burning sensation during urination
  • Pain in the rectum or gastrointestinal area
  • Developing a cough

The signs and symptoms of maternal infection can look like other medical problems. If you notice any of these symptoms during your pregnancy, reach out to your family doctor or pediatrics practitioner for a proper diagnosis.

What are the effects of maternal infections?

Maternal infections may lead to neonatal and maternal morbidity and mortality. According to research on PubMed, “Neonatal infection is a significant cause of mortality and morbidity in newborn babies. It can lead to life-threatening sepsis, which accounts for 10% of all neonatal deaths.” The incidence and prevalence of intrauterine infection are increasing, especially during the first trimester.

According to the CDC, systematic reviews have shown that infections during pregnancy can cause adverse outcomes for developing fetuses, including preterm birth, low birth weight, fetal infection, fetal growth restriction, stillbirth, birth defects, brain injury, and spontaneous abortion.

Cohort studies and meta-analyses on child health, gestational age, and other health markers have shown that pathogens present during pregnancy can induce preterm labor and increase the probability of fetal death.

Prenatal maternal infections may also cause serious complications for the mother, including urinary tract infections, hypertensive disorders, postpartum hemorrhage, decreased immunity, toxoplasma, amniotic fluid abnormalities, and complications related to abortion.

Furthermore, ascending-route maternal infections can cause chorioamnionitis, streptococcus, and funisitis and can lead to premature membrane rupturing and preterm delivery. Viral and hematogenous (carried in the blood) infections during pregnancy can also cause placental infection, which can lead to villitis and deciduitis.

Simply put, maternal infections increase the risk of illness and death for the mother and fetus. Prevention strategies and accurate and early diagnosis can help manage potential complications.

How is an infection diagnosed during pregnancy?

Accurately diagnosing a maternal infection will depend on the symptoms, the mother’s health history, and whether the mother has a history of exposure to that microorganism. Specific tests are routinely conducted as part of normal prenatal care.

Some tests determine the presence of specific microorganisms, such as rubella. Other tests, including tissue samples, antibody tests, cultures, and blood samples, are used as needed for maternal infection diagnosis. Accurate and early diagnosis will help keep you and your baby safe.