Definition
Infections in pregnancy may cause maternal illness, fetal birth defects or
disorders, postnatal medical concerns, and adverse pregnancy outcomes. Often,
maternal symptoms are mild compared with the fetal effects. Infections are spread
by vertical transmission, whereby the pregnant woman (or girl) passes an active
infection to the fetus in pregnancy through the placenta or through the birth
canal during delivery.
The timing of a maternal infection is important. In general, the earlier in
pregnancy that a pregnant woman acquires an infection, the less likely the fetus
is to acquire the infection through the placenta but the more likely the affected
fetus is to have severe symptoms. Conversely, the later in pregnancy that a
pregnant woman acquires an infection, the more likely her fetus is to acquire the
infection but with less significant abnormal findings. For sexually transmitted
diseases, the risk is greatest at time of contact with the vaginal canal during
delivery.
After blood tests, urinalyses, or vaginal cultures have confirmed a maternal
infection, additional studies of the fetus may be performed. Abnormal ultrasound
findings suggest fetal infection but cannot confirm the diagnosis. Invasive
prenatal diagnosis by amniocentesis may be available to
confirm a fetal infection but cannot detect the severity of the infection. The
prognosis, management, and treatment vary depending on the type of infection.
The TORCH Panel
Many infections may be screened using a TORCH (“toxoplasmosis,” “other,” “rubella,” “cytomegalovirus,” and “herpes”) panel. “Other” includes infections such as hepatitis B, syphilis, coxsackie virus, parvovirus, and varicella. The TORCH panel is performed on maternal blood to confirm the presence of either a past or a primary (new) infection in the pregnancy. For many infections, past exposure makes it unlikely that a current pregnancy would be at risk because of maternal immunity.
Congenital toxoplasmosis. Toxoplasmosis
is caused by Toxoplasma gondii, a common parasite that typically
does not lead to illness in otherwise healthy persons. Those who are at highest
risk are those who have outdoor pets (such as cats) who carry the parasite, those
who garden, and those who ingest uncooked meat. An infected person may present
with fever, fatigue, and sore throat. A primary infection confers a 40 percent
risk of congenital toxoplasmosis and subsequent risk of miscarriage, stillbirth, or premature delivery.
Abnormal ultrasound findings may be seen in one-third of affected fetuses;
examples of abnormalities include calcifications in the brain, water on the brain,
and an enlarged or small head size. Newborns have symptoms that range from mild to
severe, with little or absent signs of the infection at delivery. They develop
inflammation of the retina, leading to visual loss, hearing loss, seizures,
cerebral
palsy, mental retardation, enlarged liver and spleen, feeding
difficulties, and low birth weight. Antibiotics are given to reduce the
chance of vertical transmission, although medications are not 100 percent
effective.
Congenital rubella (German measles). Most females of childbearing
age are immune to rubella because of childhood vaccinations. One to two
percent of pregnant women are at risk for the virus. Pregnant women present with
flulike symptoms and arthritis. If a woman acquires the infection within the first
sixteen weeks of pregnancy, the risk is greatest (50 to 85 percent) for the fetus
to have congenital rubella syndrome, which entails hearing loss, cataracts, heart
defects, enlargement of the spleen, developmental delay, and diabetes. An
infection acquired at sixteen to twenty weeks gestation places the pregnancy at a
lower risk, and after twenty weeks, an infection does not increase the risk for
birth defects. No treatments exist to prevent vertical transmission. The vaccine
is recommended before but not during pregnancy.
Congenital cytomegalovirus. Cytomegalovirus is the most common congenital infection in
the United States. All pregnant women are susceptible to the infection, although
it is more prevalent in populations of low socioeconomic status. A primary
infection occurs in 1 to 4 percent of pregnant women and puts the pregnancy at
risk for vertical transmission. An infected woman might be asymptomatic or may
show mild symptoms that include a fever and sore throat. Of these women, one-third
will transmit the cytomegalovirus to the pregnancy.
Abnormal ultrasound findings include extra fluid around the fetus or in the fetal tissues, an enlarged heart or heart block, enlarged ventricles of the brain, and calcifications in fetal organs. Some newborns have transient symptoms such as jaundice or low birth weight. About 1 in 750 newborns will develop significant long-term complications such as hearing and vision loss, enlargement of liver and spleen, mental retardation, and seizures. Not all findings are readily apparent at delivery. Approximately one-third of severely affected newborns do not survive.
Treatment for congenital cytomegalovirus is experimental. Initial studies of administering hyperimmunoglobulin to pregnant women are promising, with resolution of abnormal ultrasound findings and delivery of healthy babies. Randomized clinical trials are needed to confirm the efficacy.
Parvovirus. Human parvovirus B19 is a common virus that causes
fifth
disease (also called erythema
infectiosum). Women who work in child care or who have an
affected family member are at greatest risk for a primary infection. Many women
remain asymptomatic or have mild flulike symptoms. A characteristic red facial
rash with a “slapped cheek” appearance is often observed. The chance of vertical
transmission in the pregnancy is approximately one-third. Risk of miscarriage and
stillbirth exists, especially if the infection was acquired in the first twenty
weeks of pregnancy. There is no increased risk for birth defects, but the fetus is
at risk for a heart infection and anemia.
Abnormal ultrasound findings include extra fluid in the fetal tissues, an
enlarged heart, and abnormal blood flow in the fetal brain. If the heart infection
and anemia are severe enough, they may ultimately result in fetal death. The
anemia might require blood transfusions through a
percutaneous umbilical blood sampling. The extra fluid may conversely disappear
and result in a normal outcome for the pregnancy. No other treatment or vaccines
are available.
Sexually Transmitted Diseases
Sexually
transmitted diseases (STDs) are routinely screened for at a
pregnant woman’s initial prenatal visit. Most STDs are transmitted at delivery by
newborn skin contact with secretions in the vaginal canal, although some may cross
the placenta. Pregnant women should avoid sexual contact and should take
appropriate precautions with partners who are untreated for STDs. Certain STDs are
transmitted to the pregnancy through diagnostic procedures such as amniocentesis.
Therefore, these procedures may not be recommended. Unlike the foregoing
infections, this and the following category include infections that can recur and
that require multiple courses of treatment.
Chlamydia. The bacterium Chlamydia
trachomatiscauses chlamydia infection, the most common
bacterial STD in the United States. Seventy-five percent of women are
asymptomatic; some have abnormal vaginal bleeding or discharge and pain with
sexual intercourse. Antibiotics are prescribed, but when untreated, chlamydia may
result in an ectopic pregnancy or a preterm delivery. If there is an
untreated chlamydia infection at the time of delivery, vaginal wall contact places
the newborn at risk for developing pneumonia and a severe eye infection
that could cause eye damage and blindness.
Congenital syphilis. Syphilis is a bacterial
infection caused by Treponoma pallidum.
Primary syphilis is characterized by an open internal or external genital sore.
Without medication, this progresses to secondary and tertiary syphilis with
findings of fever, rash, sore throat, hair loss, and, eventually, blindness and
dementia. Syphilis may be transmitted through the placenta to the fetus and result
in a miscarriage, stillbirth, and premature delivery. Syphilis is also transmitted
during both vaginal and cesarean sections, although the latter
may reduce infection rates.
Newborns may not show immediate signs of congenital syphilis. Findings include
oral and genital sores, rash, jaundice, and anemia. When untreated, children will
develop mental retardation, vision and hearing loss, seizures, and bone and teeth
damage; death can also occur. If syphilis is diagnosed before the sixteenth week
of pregnancy, penicillin is effective in preventing congenital syphilis.
After sixteen weeks, treatment is less successful.
Gonorrhea. Gonorrhea is caused by the bacterium
Neisseria gonorrhoeae. It is the second most common bacterial
STD. One-half of infected women are asymptomatic. Left untreated, it may lead to
an ectopic pregnancy, miscarriage, premature delivery, and maternal infection
after delivery. The fetal findings include decreased fetal growth. Neonatal
effects result from contact with the vaginal wall and include eye or generalized
infections and meningitis. Treatment is with antibiotics.
Hepatitis B and C. Newborns have a risk for vertical transmission
of either hepatitis B or C, viruses that infect the liver, if a pregnant woman is
a chronic carrier of the disease or if she has an acute infection. Risks to the
fetus that are transient include jaundice, fatigue, and fever. Long term, a child
is at risk for early onset cirrhosis of the liver and liver
cancer. For hepatitis B, immunizations are provided in the newborn
nursery and are 90 percent effective at preventing infection. A vaccine does not
exist for hepatitis C.
Herpes simplex virus. Genital herpes may be caused by either
herpes simplex types 1 or 2. The risk to the pregnancy includes a significant eye
infection that may result in damage or blindness. The baby is at risk if the woman
is having an active outbreak at delivery. In this circumstance, a cesarean section is often performed to avoid neonatal transmission
during labor. Maternal infection is treated with oral antibiotics. Women may be on
suppression therapy in the third trimester to prevent an outbreak at delivery. Eye
drops are routinely administered after birth to prevent a neonatal eye
infection.
Human immunodeficiency virus (HIV).
HIV is the virus that causes acquired immune deficiency
syndrome (AIDS). Vertical transmission of HIV may occur
during pregnancy or at delivery. Without treatment, the risk to the fetus is 25
percent. With antiretroviral therapy, the risk is reduced to 2 percent. Certain
medications for treating HIV may cause birth defects and disorders, so women are
switched to safer medications during pregnancy. A cesarean section may be
recommended if the woman has a large amount of virus detected, although this
recommendation is controversial.
Other Infections
Bacterial vaginosis. Bacterial vaginosis (BV) is an
imbalance of the beneficial and harmful vaginal bacteria that leads to an
overgrowth of the latter. About 10 to 30 percent of pregnant women are diagnosed
with BV, the cause of which is unknown. It is not a sexually transmitted disease,
but sexual intercourse does increase the chance of BV. Women with a new partner or
multiple sexual partners are at greatest risk. Often women are asymptomatic, but
others have a grayish-white discharge with a fishy odor. This may cause a vaginal
itch, pain, or a burning sensation. BV is associated with an increased risk for
premature labor and delivery, miscarriage and low birth weight. Treatment includes
oral antibiotics. Topical medications alleviate maternal symptoms but do not
eliminate pregnancy complications.
Influenza. Influenza is an infection of the
respiratory tract. Pregnant women are at increased risk for complications because
of a decreased immune response. Symptoms include fever, chills, achy muscles, sore
throat, and fatigue. Pregnant women often experience difficulty breathing. The
greatest chance of acquiring the flu happens during the winter season (November
through March). Data suggest an increased risk for pregnancy loss or premature
labor and delivery. An increase in birth defects has not been observed. Maternal
deaths have been reported.
Acetaminophen is given for fever control and antiviral
medications are prescribed if flulike symptoms are reported. The Centers for Disease Control and
Prevention recommends that all pregnant women receive the
seasonal and H1N1 flu vaccines. The injected flu vaccine is an inactive form of
the virus and does not place the pregnancy at increased risk for either influenza
or birth defects. The nasal vaccine is not recommended during pregnancy because it
contains live influenza virus.
Listeriosis. The bacterium Listeria
monocytogenes causes listeriosis. Although the diagnosis is
rare, pregnant women are much more likely to be diagnosed with listeriosis than
are other persons.
Listeria may be found in uncooked or undercooked food. Pregnant women should avoid lunch meats or refrigerated meats unless these meats are heated to a safe temperature. Also, pregnant women should not consume unpasteurized milk and certain dairy products.
Listeriosis increases the risk of miscarriage, stillbirth, neonatal death and premature labor. Pregnant women report mild flulike symptoms, including fever, muscle aches, diarrhea, nausea, and vomiting. More severe symptoms appear if the infection spreads to the central nervous system; the severe symptoms include maternal seizures and cognitive disorientation.
Abnormal ultrasound findings include the possibility of an enlarged fetal heart and thickening of the gastrointestinal tract, where the bacteria typically resides. Fetal infection results in death in 20 to 30 percent of cases. Newborns may have significant findings such as breathing difficulties, fever, pneumonia, sepsis, and lethargy. Newborns are at greater risk of meningitis when acquiring the infection through vaginal delivery. Treatment for listeriosis includes antibiotics to prevent vertical transmission and is successful in decreasing the stillbirth and premature delivery rate.
Group B streptococcal infection. Group B Streptococcus (GBS) is a naturally occurring bacterium commonly found in up to 25 percent of otherwise healthy women. It lives in either the vagina or the rectum of asymptomatic pregnant women. Women are tested for GBS late in their third trimester of pregnancy by a vaginal or rectal swab. GBS is the most common cause of life-threatening infections of the newborn and is associated with stillbirth. A newborn may develop sepsis, meningitis, and pneumonia. Long-term complications include vision and hearing loss and a risk for developmental delay. Penicillin is given intravenously four hours before delivery to prevent vertical transmission.
Urinary tract infection. Urinary tract
infections (UTIs) are very common during pregnancy, with most
women remaining asymptomatic. Therefore, urine cultures are performed on all
pregnant women. If left untreated, an infection of the kidneys and ureters may
occur. Symptoms include fever, back pain, anemia, and nausea and vomiting. Low
birth weight and premature delivery result. Treatment is with antibiotics for the
current infection and possible prophylactic antibiotics for women with recurrent
UTIs.
Chickenpox. A primary maternal varicella infection is associated
with the characteristic vesicular rash of chickenpox.
More significant complications are maternal bacterial infections, inflammation of
the lungs, and central nervous system involvement. During the first and second
trimesters, fetal varicella syndrome findings consist of scarred skin, eye
defects, underdeveloped limbs, small head size, and developmental delay; however,
these findings occur in only 1 percent of all fetuses. During the third trimester,
the fetus is at risk for severe symptoms and death. Pregnant women with a primary
infection are isolated from other pregnant women and infants. Immunoglobulins,
which are given when the diagnosis has been confirmed to reduce pregnancy and
newborn complications, do not prevent vertical transmission.
Impact
Although many of the aforementioned infectious diseases have either preventive measures or possible treatments in pregnancy, the illnesses remain a significant cause of fetal and maternal morbidity and death. Many of the diagnoses are not detected until after the pregnant woman or the fetus has shown significant symptoms, often when it is too late for effective interventions. Overlapping symptoms also pose difficulties for determining the exact infection.
The impact of a preterm delivery or delivery of a child with multiple medical
concerns is felt at the level of the patient and from a public health perspective.
Increased long-term care puts a strain on the medical system. Proper patient
education, and continuing drug and vaccine development, remain key components of
reducing the incidence of infections in pregnancy.
Bibliography
Addler, Stuart P., et al. “Recent Advances in the Prevention and Treatment of Congenital Cytomegalovirus Infections.” Seminars in Perinatology 31 (2007): 10-18.An overview of congenital cytomegalovirus and summary of data regarding newer prenatal treatment by hyperimmunoglobulin.
Al-Safi, Z. A., V. I. Shavell, and B. Gonik. “Vaccination in Pregnancy.” Women’s Health (London) 7 (2011): 109-119. Article argues for the importance of clinical discussions of vaccinations in pregnant women and of the risks to their fetuses.
Gratzl, R., et al. “Follow-up of Infants with Congenital Toxoplasmosis Detected by Polymerase Chain Reaction Analysis of Amniotic Fluid.” European Journal of Clinical Microbiology and Infectious Disease 17 (1998): 853-858. A prospective longitudinal study of infants diagnosed prenatally with congenital toxoplasmosis and treated with antibiotics. Provides follow-up on the medical outcomes throughout the first year of life.
Khare, Manjiri. “Infectious Disease in Pregnancy.” Current Obstetrics and Gynaecology 15 (2005): 149-156. An overview of the many infectious diseases of pregnancy, with discussion of their impact.
Yinon, Y., et al. “Cytomegalovirus Infection in Pregnancy.” Journal of Obstetrics and Gynaecology Canada 32 (2010): 348-354. An updated examination of cytomegalovirus infection in pregnant women.
No comments:
Post a Comment