Perinatal infection


An infection caused by a bacteria or virus that can be passed from a mother to her baby during pregnancy or delivery is called a perinatal infection.


Perinatal infections include bacterial or viral illnesses that can be passed from a mother to her baby either while the baby is still in the uterus or during the delivery process. Maternal infection can, in some cases, cause complications at birth. The mother may or may not experience active symptoms of the infection during the pregnancy. Some perinatal infections are sexually transmitted.


Transmission of many perinatal infections occurs during childbirth , particularly in cases when invasive techniques such as episiotomy or artificial rupture of membranes are employed. In other cases, transmission may occur during pregnancy, if the infectious agent can cross the placental barrier, and it may occur during breastfeeding, if the infectious agent can be found in breast milk.


The incidence of perinatal infection depends on the causative agent of infection. For example, perinatal transmission of cytomegalovirus occurs in two to 24 out of every 1,000 live births. The rate of transmission of genital herpes during pregnancy is one to two out of every 2,000 pregnancies; the rate of transmission during childbirth changes to one out of every 2,000 to 5,000 live births. Perinatal transmission of group beta streptococcus causes neonatal infection in one to five out of every 1,000 live births, and rubella (German measles ), 0.02 out of every 1,000 live births. HIV is transmitted from untreated mother to child in 25 to 40 percent of cases, but in only 1 percent of cases if mother receives treatment and the infant receives prophylaxis.

Causes and symptoms

The following represent some of the more common infections that can be transmitted perinatally.


The bacterium Chlamydia trachomatis is the cause of the most common bacterial sexually transmitted disease in the United States, causing more than 4 million infections each year. The majority of women with chlamydial infection experience no obvious symptoms. The infection affects the reproductive tract and causes pelvic inflammatory disease, infertility, and ectopic pregnancy (when the fertilized egg implants somewhere other than in the uterus). This infection can cause premature rupture of the membranes and early labor. It can be passed to the infant during delivery and can cause ophthalmia neonatorum (an eye infection) within the first month of life and pneumonia within one to three months of age. Symptoms of chlamydial pneumonia are a repetitive cough and rapid breathing. Wheezing is rare and the infant is usually without a fever .


Cytomegalovirus (CMV) is a common virus in the herpes virus family. It is found in saliva, urine, and other body fluids and can be spread through sexual contact or other more casual forms of physical contact such as kissing. In adults, CMV may cause mild symptoms of swollen lymph glands, fever, and fatigue. Many people who carry the virus experience no symptoms at all. Infants can become infected with CMV while still in the uterus if the mother becomes infected or develops a recurrence of the infection during pregnancy. Although most infants exposed to CMV before birth develop normally and do not show any symptoms, as many as 6,000 infants who were exposed to CMV before birth are born with serious complications each year. CMV interferes with normal fetal development and can cause mental retardation , blindness, deafness, or epilepsy in these infants.

Genital herpes

Genital herpes, which is usually caused by herpes simplex virus type 2 (HSV-2), is a sexually transmitted disease that causes painful sores on the genitals. Women who have their first outbreak of genital herpes during pregnancy are at high risk of miscarriage or delivering a low birth weight baby. The infection can be passed to the infant at the time of delivery if the mother has an active sore. The most serious risk to the infant is the possibility of developing HSV-2 encephalitis , an inflammation of the brain, with symptoms of irritability and poor feeding.

Hepatitis B

Hepatitis B is a contagious virus that causes liver damage and is a leading cause of chronic liver disease and cirrhosis. Approximately 20,000 infants are born each year to mothers who test positive for the hepatitis B virus. These infants are at high risk for developing hepatitis B infection through exposure to their mothers blood during delivery.

Human immunodeficiency virus (HIV)

Human immunodeficiency virus (HIV) is a serious, contagious virus that causes acquired immunodeficiency syndrome ( AIDS ). About 25 to 40 percent of untreated pregnant women pass the infection on to their newborn infants, while only 1 percent of treated pregnant women transmit the virus. There are often no symptoms of HIV in infants, but within a few months most infants who are infected show signs of opportunistic infections such as failure to thrive , chronic thrush, and persistent diarrhea .

Human papillomavirus

Human papillomavirus (HPV) is a sexually transmitted disease that causes genital warts and can increase the risk of developing some cancers. HPV appears to be transferred from the mother to the infant during the birth process and can cause tracheal narrowing due to lesions (warts) from the virus.

Rubella (German measles)

Rubella is a virus that causes German measles, an illness that includes rash, fever, and symptoms of an upper respiratory tract infection. Most people are exposed to rubella during childhood and develop antibodies to the virus so they never get it again. Rubella infection during early pregnancy can pass through the placenta to the developing infant and cause serious birth defects, including heart abnormalities, mental retardation, blindness, and deafness.

Group beta streptococcus

Group beta streptococcus (GBS) infection is the most common bacterial cause of infection and death in newborn infants. Although rates have declined in the United States since the introduction of antibiotics to at-risk women during labor in the 1980s, about 1,600 cases and 80 newborn deaths still occur each year. In women, GBS can cause vaginitis and urinary tract infections. Both infections can cause premature birth, and the bacteria can be transferred to the infant in the uterus or during delivery. GBS causes pneumonia, meningitis , and other serious infections in infants.


Syphilis is a sexually transmitted bacterial infection that can be transferred from a mother to an infant through the placenta before birth. Up to 50 percent of infants born to mothers with syphilis are premature or stillborn or die shortly after birth. Infected infants may have severe birth defects. Those infants who survive infancy may develop symptoms of syphilis up to two years later.

When to call the doctor

Pregnant women who exhibit symptoms of infection should contact their healthcare provider to determine if the infection can be passed vertically to the child during pregnancy, childbirth, and/or breastfeeding. In some cases, early detection and treatment of infection can minimize the risk of perinatal transmission.


How a bacterial or viral infection is diagnosed depends on the causative agent. Examples include the following:

  • Chlamydia can be diagnosed by taking a cotton swab sample of the cervix and vagina during the third trimester of the pregnancy. Chlamydial cell cultures take three to seven days to grow. DNA probes are available for more rapid diagnosis.
  • Past or recent infection with cytomegalovirus (CMV) can be identified by antibody tests and CMV can be grown from body fluids.
  • Genital herpes is suspected with the outbreak of a particular kind of genital sore. The sore can be cultured and tested to confirm that HSV-2 is present.
  • Hepatitis B can be identified through a blood test for the hepatitis B surface antigen (HBsAg) in pregnant women. The test is part of prenatal health programs.
  • Human immunodeficiency virus (HIV) can be detected using a blood test and is part of most prenatal screening programs.
  • Human papillomavirus (HPV) causes the growth of warts in the genital area. The wart tissue can be removed with a scalpel and tested to determine what type of HPV virus caused the infection.
  • Pregnant women are usually tested for antibodies to rubella, which would indicate that they have been previously exposed to the virus and, therefore, would not develop infection during pregnancy if exposed.
  • Group beta streptococcus (GBS) can be detected by a vaginal or rectal swab culture and sometimes from a urine culture. Blood tests can be used to confirm GBS infection in infants who exhibit symptoms.
  • Pregnant women are usually tested for syphilis as part of the prenatal screening, generally with a blood test.


Methods of treating some of the more common causes of perinatal infection include:

  • Chlamydia: Pregnant women can be treated during the third trimester with oral erythromycin, for seven to 14 days depending on the dose used. Newborn infants can be treated with erythromycin liquid for ten to 14 days at a dosage determined by their body weight.
  • Cytomegalovirus (CMV): No drugs or vaccines were as of 2004 available for prevention or treatment of CMV except in immunocompromised persons.
  • Genital herpes: The antiviral drugs acyclovir or famciclovir can be administered to the mother during pregnancy. Little is known about the risks of these drugs to the fetus; however, the risk of birth defects does not seem to be any higher than for women who do not take these medications. Infants with suspected HSV-2 can be treated with acyclovir. Delivery of the infant by cesarean section is recommended if the mother has an active case of genital herpes.
  • Hepatitis B: Infants born to mothers who test positive to the HBsAg test should be treated with hepatitis B immune globulin at birth to give them immediate protection against developing hepatitis B. All infants should also receive a series of three hepatitis B vaccine injections as part of their routine immunizations.
  • Human immunodeficiency virus (HIV): Recent studies have shown that prenatal care and HIV testing before delivery are major opportunities for preventing perinatal HIV infection . Pregnant women with HIV should be treated as early in the pregnancy as possible with zidovudine (AZT). Other newer drugs designed to treat HIV/AIDS also may be used during pregnancy with the knowledge that these drugs may have unknown effects on the infant. Infants born with HIV should receive aggressive drug treatment to prevent development of AIDS. Most of the drugs designed to treat HIV are routinely used during pregnancy because of the mother's health needs and because transmission rate is directly related to the mother's viral load. Teratogenicity is not fully established for some of the subsequent HIV medications.
  • Human papillomavirus: Genital warts are very difficult to treat and frequently recur even after treatment. They can be removed by cryotherapy (freezing), laser or electrocauterization (burning), or surgical excision (cutting). Some medications (imiquimod 5% cream, podophyllin, trichloroacetic acid, or topical 5-fluorouracil) can be applied to help dissolve genital warts. Cesarean delivery rather than vaginal delivery reduces the risk of transmission of HPV from mothers to infants.
  • Rubella (German measles): No treatment is available. Some healthcare providers may recommend giving the mother an injection of immune globulin (to boost the immune system to fight off the virus) if she is exposed to rubella early in the pregnancy. However, no evidence to support the use of these injections existed as of 2004. Exposure to rubella early in pregnancy poses a high risk that the infant will have serious birth defects. Termination of the pregnancy may be considered. Women who have not been previously exposed to rubella are usually vaccinated immediately after the first pregnancy to protect infants of future pregnancies.
  • Group beta streptococcus (GBS): Pregnant women diagnosed with GBS late in the pregnancy should be treated with antibiotics injected intravenously to prevent premature labor. In 2003, the Centers for Disease Control and Prevention (CDC) issued revised guidelines for preventing perinatal GBS disease. They began recommending that women not only be tested as soon as they learn of their pregnancy, but again at 35 to 37 weeks of gestation. The CDC also recommended updated prophylaxis regimens for women with penicillin allergies , as well as other guidelines for patients with threatened preterm deliveries and other recommendations. If transmission of GBS to the newborn infant already is suspected or if the baby develops symptoms of infection, infants often are treated with antibiotics.
  • Syphilis: Antibiotic therapy, usually penicillin, given early in the pregnancy can be used to treat the infection and may prevent transmission to the infant.


The prognosis of a neonate who has contracted an infection perinatally depends on the specific infection. Examples include the following:

  • Chlamydia: Without treatment, the most serious consequences of chlamydial infection are related to complications of premature delivery. Treatment of the mother with antibiotics during the third trimester can prevent premature delivery and the transfer of the infection to the baby. Infants treated with antibiotics for eye infection or pneumonia generally recover.
  • Cytomegalovirus: The chance for recovery after exposure to CMV is very good for both the mother and the infant. Exposure to CMV can be serious and even life threatening for mothers and infants whose immune systems are compromised, for example, those receiving chemotherapy or who have HIV/AIDS. Those infants who develop birth defects after CMV exposure may have serious, lifelong complications.
  • Genital herpes: Once a woman or infant is infected, outbreaks of genital herpes sores can recur at any point during their lifetimes.
  • Hepatitis B: Infants treated at birth with immune globulin and the series of vaccinations are protected from development of hepatitis B infection. Infants infected with hepatitis B develop a chronic, mild form of hepatitis and are at increased risk for developing liver disease.
  • Human immunodeficiency virus (HIV): A combination of treatment with highly active antiretroviral therapy during pregnancy, zidovudine (AZT) during delivery, and AZT to the baby for six weeks after birth significantly reduces the chance that the infant will be infected with HIV from the mother.
  • Human papillomavirus: Once infected with HPV, there is a lifelong risk of developing warts and an increased risk of some cancers.
  • Rubella (German measles): Infants exposed to rubella virus in the uterus are at high risk for severe birth defects, including heart defects, blindness, and deafness.
  • Streptococcus: Infection of the urinary tract or genital tract of pregnant women can cause premature birth. Infants infected with GBS can develop serious, life-threatening infections.
  • Syphilis: Premature birth, birth defects, or the development of serious syphilis symptoms is likely to occur in untreated pregnant women.


Use of a barrier method of contraceptive (e.g. condom ) can prevent transmission of some sexually transmitted infections during intercourse. Intravenous drug use and sexual intercourse with infected partners increase the risks of exposure to most of these infections. Pregnant women can be tested for many of the bacterial or viral infections described; however, effective treatment may not be available to protect the infant.

In some cases, the method of childbirth may impact the chance of passing an infection from mother to child. For instance, research has shown that delivering a baby by caesarian section over vaginal delivery reduces the risk of transmitting HIV from mother to child.

Nutritional concerns

A woman's nutritional status may contribute to her ability to fight off infections, particularly in cases of malnutrition . A well-balanced diet rich in nutrients such as folic acid , calcium, iron, zinc, vitamin D, and the B vitamins is recommended for pregnant women. Mothers are recommended to eat approximately 300 additional calories day (above and beyond a normal nonpregnancy diet) to support the fetus's growth and development.


Cesarean section —Delivery of a baby through an incision in the mother's abdomen instead of through the vagina; also called a c-section, cesarean birth, or cesarean delivery.

Ectopic pregnancy —A pregnancy that develops outside of the mother's uterus, such as in the fallopian tube. Ectopic pregnancies often cause severe pain in the lower abdomen and are potentially life-threatening because of the massive blood loss that may occur as the developing embryo/fetus ruptures and damages the tissues in which it has implanted.

Encephalitis —Inflammation of the brain, usually caused by a virus. The inflammation may interfere with normal brain function and may cause seizures, sleepiness, confusion, personality changes, weakness in one or more parts of the body, and even coma.

Episiotomy —An incision made in the perineum (the area between the vulva and the anus) during labor to assist in delivery and to avoid abnormal tearing of the perineum.

Perinatal —Referring to the period of time surrounding an infant's birth, from the last two months of pregnancy through the first 28 days of life.

Pneumonia —An infection in which the lungs become inflamed. It can be caused by nearly any class of organism known to cause human infections, including bacteria, viruses, fungi, and parasites.

Parental concerns

Minimizing the risk of transmitting a maternal infection to a fetus is often a major concern for parents. The first step is identifying possible maternal infections. Proper prenatal care in many cases allows for early diagnosis and thus early treatment of certain infections, thus improving the newborn's prognosis.



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Altha Roberts Edgren Teresa G. Odle Stephanie Dionne Sherk

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