Maternal to Fetal Infections
Maternal to Fetal Infections
Maternal to fetal infections are transmitted from the mother to her fetus, either across the placenta during fetal development (prenatal) or during labor and passage through the birth canal (perinatal).
Antibodies in the maternal blood prevent most infections from being transmitted to the fetus. However some maternal-to-fetal infections, particularly in the first trimester of pregnancy, can cause miscarriage or severe birth defects. Other infections can cause preterm labor, fetal or neonatal death, or serious illness in newborns. Perinatal transmissions infect the fetus after its protective membranes rupture—the waters break—and during labor and delivery when the fetus is exposed to maternal blood. Perinatal transmission is more likely if the waters break prematurely.
Up to one-third of all people are infected with toxoplasmosis. The U.S. Centers for Disease Control and Prevention (CDC) estimate that 25-45% of women of childbearing age carry the parasite Toxoplasma gondii that causes toxoplasmosis. Very few infected people have symptoms and most pregnant women have antibodies that protect the fetus from infection. However in one-third of women who are infected for the first time during pregnancy, the parasite infects the placenta and enters the fetal circulation. Congenital (present at birth) infection occurs in one out of every 800-1,400 infants born to infected mothers. The fetal infection rate is above 60% if maternal infection occurs during the third trimester, but the most severe fetal complications occur with first-trimester infection.
Viral respiratory infections
Cytomegalovirus (CMV) is the most common infection that can be transmitted to a fetus. From 50-80% of childbearing-age women have been infected by CMV prior to pregnancy. However about 1-3% of women have their first or primary CMV infection during pregnancy and about one-third of these infections are transmitted to fetuses. Although most infants with congenital CMV have no problems, infection in early pregnancy can cause miscarriage or birth defects and CMV is a leading cause of congenital deafness. In later pregnancy CMV infection may cause preterm labor, stillbirth, or serious newborn illness. In the United States about 8,000 infants annually are born with potentially fatal CMV-related birth defects.
Fifth disease, caused by the parvovirus B19, is very common among children. About one-half of all adults are susceptible. About one-third of infants whose mothers contract fifth disease during pregnancy show signs of infection at birth. Although not usually dangerous, fifth disease contracted early in pregnancy can cause miscarriage or severe fetal anemia (low blood count) that can lead to congestive heart failure.
A fetus infected from its mother by Varicella zoster virus may develop pocks that can cause limb deformities early in development. If a woman contracts varicella (chickenpox) during the first 20 weeks of pregnancy, there is a 2% chance that her newborn will have varicella syndrome. However the greatest risk from varicella is if the mother contracts the virus just before delivery when she has not yet produced antibodies to protect the newborn.
In the past rubella was a common cause of birth defects. However routine vaccinations have made prenatal infection rare in the developed world. Rubella infection during the first 10 weeks of pregnancy may cause fetal death and more than 50% of newborns have severe birth defects. Infections contracted later in pregnancy do not cause congenital defects, although the newborn may become seriously ill and eventually develop diabetes mellitus.
Invasive group B streptococcal (GBS) disease is the most common cause of life-threatening infection in newborns. Up to 20% of pregnant women carry GBS in their vaginas during the last trimester, with the potential of infecting the fetus during birth. Although premature infants are more susceptible to GBS, 75% of infected infants are full-term. During the 1970s GBS emerged as the most common cause of newborn sepsis, or blood infection, and meningitis—infection of the fluid and lining surrounding the brain. GBS also is a frequent cause of newborn pneumonia. Maternal infection at conception or within the first two weeks of pregnancy may lead to hearing and vision loss and mental retardation. Between 1993 and 2002 congenital GBS infection in the United States decreased from 1.7 per 1,000 live births to 0.4 per 1,000 due to the use of antibiotics during delivery.
The food-borne bacterial infections listeriosis—caused by Listeria monocytogenes—and salmonellosis or food poisoning—caused by Salmonella bacteria—can be transmitted to a fetus. Listeria monocytogenes is ubiquitous in soil and groundwater, on plants, and in animals. Most human infections result from ingesting contaminated foods. Hormonal changes make pregnant women about 20 times more likely than other healthy adults to contract listeriosis and about one-third of all cases occur in pregnant women. Listeriosis can cause miscarriage, fetal or newborn death, premature delivery, or severe illness in the mother and infant.
Each year an estimated 8,000 pregnant women in the United States are infected with syphilis caused by the spirochete Treponema pallidum. Rising rates of syphilis among pregnant women are increasing the number of infants born with congenital syphilis. Congenital syphilis is a severe, disabling, and often life-threatening disease that can cause facial deformity, blindness, and deafness.
Every year in the United States an estimated 40,000 pregnant women are infected with gonorrhea—caused by Neisseria gonorrhoeae—and an estimated 200,000 are infected with chlamydia—caused by Chlamydia trachomatis. Chlamydia can cause premature membrane rupture and labor. Both infections can cause newborn conjunctivitis—a discharge of pus from the eyes.
Sexually transmitted viral infections
Each year an estimated 8,000 pregnant American women are infected with HIV, the human immunodeficiency virus that causes acquired immune deficiency syndrome (AIDS). About 20-25% of pregnant women with untreated HIV transmit it to their fetuses. In developed countries widespread HIV testing and anti-retroviral therapy have reduced maternal-fetal transmission dramatically.
Genital herpes are caused by herpes simplex virus (HSV) type-2 and, less frequently, by HSV type-1 that usually causes cold sores. About 25% of American adults are infected with HSV-2, affecting one in 1,800-5,000 live births. There is little risk of fetal transmission if the mother is infected before the third trimester and has no genital sores at the time of delivery. However infection during the third trimester—when the virus is likely to be active and the mother has not yet made sufficient antibodies to protect her fetus—may lead to congenital HSV infection. This can seriously damage the newborn's eyes, central nervous system, and internal organs, lead to mental retardation and, rarely, death.
Genital or venereal warts are caused by some types of human papillomavirus (HPV). At least 20 million Americans are infected and about 5.5 million new cases are reported annually. Genital warts are highly infectious and tend to grow faster during pregnancy. If vaginal warts are very large they may interfere with the infant's passage through the birth canal, necessitating a cesarean section (C-section).
An estimated 8,000 pregnant women are infected with hepatitis B in the United States every year. They are at risk for premature delivery and, if untreated, newborns may develop chronic liver disease.
Causes and symptoms
The single-celled protozoan Toxoplasma gondii produces eggs in cat intestines. The eggs shed in cat feces and can survive for up to 18 months in the soil. Human infection occurs from handling contaminated soil or feces or by ingesting raw or undercooked meat from infected animals.
Although the symptoms of toxoplasmosis usually are very mild or absent, infection occurring early in fetal development can cause:
- inflammation of the brain, heart, or lungs
- severe or prolonged jaundice
- an enlarged liver and spleen
- an eye inflammation called choriorectinitis which can lead to blindness
- severe illness or death shortly after birth
Symptoms of congenital toxoplasmosis may appear months or years after birth and may include:
- seizures or other neurological problems
- visual impairment
- hearing loss
- mental retardation
Viral respiratory infections
Although most CMV-infected newborns have no symptoms, 10-15% may exhibit:
- low birth weight
- small bruises
- enlarged liver and spleen
- hernias in the groin
- microcephaly or hydrocephaly
- respiratory problems
- brain damage
From 0.5-15% of CMV-infected infants develop hearing, vision, or neurological problems over several years. In addition to crossing the placenta, there is a 1% risk of perinatal CMV transmission.
Symptoms of congenital fifth disease include:
- bright red rash on the cheeks
- lacy, red rash on the neck, trunk, and legs
- joint pain
Varicella syndrome in a newborn is characterized by:
- abnormally small limbs and head
- scarring of the skin
- eye defects
- mental retardation
In addition to various birth defects, newborns infected with rubella early in the pregnancy may have:
- low birth weight
- bluish-red skin lesions
- enlarged lymph nodes
- enlarged liver and spleen
- brain inflammation
Although most GBS carriers have no symptoms, GBS in pregnant women may cause:
- bladder or urinary tract infections
- infection of the womb
Pregnant women are more likely to transmit GBS to their fetuses if they:
- previously delivered a GBS-infected baby
- have a urinary tract infection caused by GBS
- carry GBS late in pregnancy
- begin labor or membrane rupture before 37 weeks of gestation
- have membrane rupture 18 hours or more before delivery
- experience fever during labor
Symptoms of congenital GBS infection include:
- breathing difficulties
Listeriosis may cause flu-like symptoms and the infection can be transmitted prenatally even if the mother has no symptoms.
Symptoms of salmonellosis can be severe in pregnant women and newborns and may include:
- abdominal cramps
- rarely, meningitis
Syphilis can be transmitted to a fetus either prenatally or perinatally if the mother is infected during pregnancy or was inadequately treated for a past infection. In adults syphilis usually causes genital lesions 10-90 days after exposure, with a rash developing six weeks later. Symptoms may go unnoticed. Congenital syphilis can cause premature birth or stillbirth.
A surviving newborn with untreated congenital syphilis may have no initial symptoms but may gain little weight and, during the first month of life, develop:
- rash or small fluid-filled blisters on the palms and soles of the feet
- raised bumps around the nose, mouth, and diaper region
- cracks around the mouth
- nasal discharge of mucus, pus, or blood
- enlarged lymph nodes, liver, and spleen
- bone inflammation
- rarely, meningitis
Early-stage symptoms of congenital syphilis include:
- failure to thrive
- severe congenital pneumonia
- rash and lesions around the mouth, genitalia, and anus
- bone lesions
- nose cartilage infection or saddle nose (lacking a bridge)
Symptoms of late-stage congenital syphilis include:
- copper-colored rashes on the face, palms, and soles
- scarring around earlier lesions
- gray patches on the anus or outer vagina
- notched or peg-shaped teeth
- joint swelling
- bone pain
- abnormalities in the lower leg bones
- neurological conditions
- visual loss or blindness
- hearing loss or deafness
Both gonorrhea and chlamydia can be transmitted perinatally. Conjunctivitis caused by gonorrhea usually appears two to seven days after birth. Conjunctivitis caused by chlamydia usually appears 5-12 days after birth, although sometimes it takes six weeks to develop.
Symptoms of gonorrhea in women, if present, may include:
- bleeding during vaginal intercourse
- pain or burning with urination
- yellow or bloody vaginal discharge
- pelvic inflammatory disease
Sexually transmitted viral infections
HIV can be transmitted through the placenta, during labor and delivery, and through breast milk. HIV-infected infants do not have symptoms at birth, although about 15% develop serious symptoms or die within the first year. Almost one-half die by the age of 10.
Factors that may increase the risk of maternal HIV transmission include:
- the mother's viral load—the amount of HIV in her blood
- use of illicit drugs
- severe inflammation of the fetal membranes
- a prolonged period between membrane rupture and delivery
Most women carrying HSV never have recognizable symptoms; however a first episode of genital herpes during pregnancy can be passed to the fetus and may cause premature birth. Both HSV-1 and HSV-2 can be transmitted during birth if the mother has active genital sores, causing facial or genital herpes in the newborn.
Initial symptoms of congenital herpes usually appear within four weeks of birth and may be quite mild:
- blisters on the skin
- loss of appetite
More serious symptoms of congenital HSV infection include:
- a skin rash with small fluid-filled blisters
- chronic or recurring eye and skin infections
- widespread infection affecting many organs including the lungs and liver
- a life-threatening brain infection called herpes encephalitis
Nearly 50% of women infected with HPV have no symptoms although genital warts may appear weeks or months after infection. They can become larger during pregnancy causing difficulty with urination. Vaginal warts can reduce the elasticity of the vagina and cause obstruction during delivery. Symptoms of congenital HPV infection may include lung infection and obstructed air passages from warts inside the windpipe.
Although hepatitis B can be transmitted to the fetus through the placenta, most often it is transmitted perinatally. Since the virus is thought to pass through the umbilical cord, C-sections do not prevent transmission. Congenital hepatitis B can cause chronic liver infection, although symptoms usually do not become apparent until young adulthood.
Diagnosis of maternal, fetal, or congenital infection can be difficult. An obstetrician may diagnose a maternal infection based on the woman's symptoms and blood tests. Sometimes a fetal infection can be diagnosed using ultrasound. Diagnosis of congenital infections in newborns may be based on a physical examination, symptoms, and blood or urine tests. Ultrasound scanning may be used to image the newborn's brain and echocardiography may be used to diagnose heart problems.
Prenatal tests for toxoplasmosis include:
- a blood test for maternal antibodies
- testing of the amniotic fluid and fetal blood
- fetal ultrasound
Postnatal diagnosis for congenital toxoplasmosis may include:
- antibody tests of the cord blood and cerebrospinal fluid
- an ophthalmologic examination
- neurological examinations
- a computed axial tomography (CT or CAT) scan
A 2005 study advised that all pregnant women and newborns have blood screenings for toxoplasmosis
Viral and bacterial infections
Diagnostic procedures include:
- blood tests for maternal antibodies against CMV or fifth disease
- ultrasound for fetal fifth disease
- bacterial cultures from blood, spinal fluid, skin, the vagina, or rectum for GBS
- a maternal blood test for listeriosis
Sexually transmitted infections (stis)
The CDC recommends that all pregnant women be screened on their first prenatal visit for syphilis, gonorrhea, chlamydia, HIV, hepatitis B, and hepatitis C.
Infants are tested for syphilis at birth. Syphilis in an older infant may be diagnosed by a blood test, a lumbar puncture to look for signs of syphilis in the brain and central nervous system, an ophthalmologic examination, dark-field microscopy to visualize the spirochete, or bone x rays.
Maternal gonorrhea can be diagnosed by staining or culturing a cervical smear or testing for the bacterial DNA in a urine or cervical sample.
Women who were not screened for HIV during pregnancy may be screened during labor or delivery with a rapid test. The most common screening for HIV tests for antibodies in the blood; however most infants born to infected mothers test positive for 6-18 months because of the presence of maternal antibodies. An HIV blood test performed within 48 hours of birth detects only about 40% of infections, so testing is repeated at one and six months.
An HSV culture from an affected genital site—preferably on the first day of the outbreak—can test for herpes simplex. A blood test can show if a person has ever been infected with HSV and may distinguish between HSV-1 and HSV-2 and old or recently acquired infections. An examination or test can indicate whether a pregnant woman has active genital herpes near the time of delivery.
Genital warts are diagnosed visually. Vinegar may whiten infected areas to make them more visible. Cervical warts can be diagnosed by removing a piece of tissue for microscopic examination.
Infants born with serious infections are treated in the neonatal care unit with intravenous drugs. Infants born to infected mothers may be treated with medications even if they show few or no signs of infection.
Maternal toxoplasmosis is treated with spiramycin during the first and early second trimesters of pregnancy. Fetal toxoplasmosis may be treated by giving the mother pyrimethamine and sulfonamides such as sulfadiazine during the later second and third trimesters.
Newborns with symptoms of toxoplasmosis are treated with pyrimethamine and sulfadiazine for one year; leucovorin for one year to protect the bone marrow from pyrimethamine toxicity; corticosteroids for heart, lung, or eye inflammations; clindamycin; and a corticosteroid to reduce the inflammation of chorioretinitis.
Viral respiratory infections
There is no effective treatment for CMV, although ganciclovir may be used to treat some symptoms.
Fetal anemia caused by fifth disease may resolve on its own. If the fetus is at risk for heart failure, a fetal blood transfusion may be performed. The mother also may receive medication that passes through the placenta to the fetus.
Exposure to chickenpox or rubella by a nonimmune pregnant woman may be treated with an injection of immune globulin to help prevent fetal transmission. Congenital chickenpox is treated immediately to prevent serious complications or death. There is no specific treatment for rubella infection.
Pregnant women with GBS in their urine are treated with penicillin. Most GBS-carriers are treated with intravenous antibiotics—from membrane rupture through labor—to prevent fetal transmission. Infants born with congenital GBS infections are treated immediately with intravenous antibiotics.
Maternal and congenital listeriosis and syphilis are treated with antibiotics.
Maternal gonorrhea may be treated with cefixime, ceftriaxone, or levofloxacin. Since women often are infected with both gonorrhea and chlamydia, a combination of antibiotics such as ceftriaxone and doxycycline or azithromycin are used to treat both infections.
An antibiotic ointment such as silver nitrate is placed under the eyelids of all newborns as preventative treatment for gonorrhea. An infant born to a gonorrhea-infected mother is treated with penicillin. Conjunctivitis caused by gonorrhea is treated with an eye ointment containing polymyxin and bacitracin, erythromycin, or tetracycline. An antibiotic such as ceftriaxone is given intravenously. Congenital chlamydia is treated with erythromycin eye ointment and oral tablets.
Women who are being treated for HIV with combination drugs may stop treatment for the first trimester of pregnancy to avoid the risk of birth defects and to avoid missing doses due to vomiting, which can cause the growth of drug-resistant HIV strains. Although the side effects of the anti-retroviral drugs may worsen during pregnancy, stopping treatment can worsen a woman's condition.
Zidovudine (ZDV, AZT, Retrovir) is the only drug that has been proven to help prevent fetal HIV infection. HIV-positive pregnant women usually take ZDV from 14-34 weeks of gestation. During delivery the mother receives ZDV intravenously. The newborn is given liquid ZDV every six hours for six weeks. A 2004 study of HIV-positive Thai women found that oral ZDV beginning at 28 weeks of gestation, with a single dose of nevirapine during labor, greatly reduces HIV transmission.
Pneumonia caused by Pneumocystis carinii often is the first AIDS-related illness to appear in HIV-infected infants and is a major cause of death during the first year. The CDC recommends that all babies born to HIV-infected mothers be treated with antipneumonia drugs beginning at four—six weeks and continuing until the infant is found to be HIV-negative.
Although there is no cure for genital herpes, outbreaks just prior to delivery may be prevented by acyclovir (Zovirax), famciclovir (Famvir), or valacyclover (Valtrex). An HSV-infected newborn is treated immediately with intravenous antiviral drugs such as acyclovir. Eye infections are treated with trifluridine drops.
There is no cure for HPV and treatment during pregnancy often is ineffective, although it may include:
- Imiquimod cream
- 5% 5-fluorouracil cream
- trichloroacetic acid
- freezing or burning the warts with a laser
- surgical removal
- alpha interferon injected into the wart
HPV infection in newborns is treated by surgically removing the warts. If the warts obstruct breathing passages, frequent laser surgery is required. Interferon may be used to reduce the likelihood of recurrence.
Non-infected pregnant women may begin the hepatitis B vaccine series if they are at high-risk for infection. Infants born to mothers infected with hepatitis B are given both the first dose of hepatitis B vaccine and hepatitis B immune globulin within 12 hours of birth. The second and third doses of vaccine are given at one month and six months of age.
Maternal treatment with spiramycin for toxoplasmosis infection occurring within the first two weeks of pregnancy prevents transmission to the fetus. The prognosis for congenital toxoplasmosis depends on its severity.
With treatment most infants with congenital CMV survive, although almost all suffer from its effects.
A GBS-carrier's risk of delivering an infected child decreases from one in 200 to one in 4,000 if she is treated with antibiotics. GBS-infected mothers are less likely to infect their newborns if treated with antibiotics during labor. Although immediate penicillin treatment for GBS-infected newborns is very effective, about 5% of GBS-infected newborns die.
Many fetuses infected with syphilis early in gestation are stillborn. Nearly 50% of untreated fetuses die shortly before or after birth. However the fetus is at minimal risk if the mother receives adequate treatment with penicillin during pregnancy.
Pregnant women on combined antiretroviral therapy are at a 1-2% risk of transmitting HIV to the fetus. If the mother's viral load is under 1,000 and she is treated with ZDV, the risk of transmission is almost zero. Mothers with a high viral load may reduce the risk of transmission by having a C-section before labor begins and the membranes rupture. Congenital HIV infection that is treated with combination drugs, including protease inhibitors, may reduce the risk of death by 67%.
Women with an active HSV infection can reduce the risk of fetal transmission with a C-section. Although immediate medication for the newborn may prevent or reduce the damage from HSV, one-half of infants born with widespread HSV infections die and the other one-half may have brain damage.
Infants born to hepatitis B-infected mothers have a greater-than-95% chance of being protected against the virus if they receive the first dose of vaccine and immune globulin within 12 hours of birth.
General advice for preventing infection during pregnancy includes:
- good hygiene—including frequent thorough hand washing and not sharing food or drinks—particularly for mothers who have or work with young children and may be at risk for CMV
- vaccinations several months before a planned pregnancy
- appropriate vaccinations after the first trimester of pregnancy
- contacting a healthcare provider immediately upon being exposed to a transmittable infection
To avoid Taxoplasma during pregnancy women should:
- keep cats indoors
- avoid handling cat litter without rubber gloves and wash thoroughly
- disinfect the cat box with boiling water for five minutes
- cover sandboxes
- wear gloves for gardening and wash afterwards
- avoid insects that may have been exposed to cat feces
- wash after handling cats, raw meat or poultry, soil, or sand
- avoid raw or undercooked meat and poultry, unwashed fruits and vegetables, raw eggs, and unpasteurized milk
- kill Taxoplasma by freezing food or cooking it thoroughly
All non-immune women of childbearing age should be vaccinated against rubella and chickenpox before pregnancy. Pregnant women should be tested for immunity to rubella at their first prenatal visit.
Women should be tested for GBS between 35 and 37 weeks of pregnancy to determine whether the bacteria are likely to be present at delivery.
Since Listeria can grow at temperatures below 40°F(4°C), pregnant women should handle food cautiously and avoid:
- hot dogs and luncheon and deli meats unless they are reheated to steaming
- soft cheeses
- refrigerated meat spreads
- refrigerated smoked seafood unless it is in a cooked dish
- raw unpasteurized milk
Pregnant women should use precooked or ready-to-eat perishables immediately, clean the refrigerator regularly, and keep the refrigerator at or below 40°F(4°C).
Salmonellosis may be prevented by:
- cooking all meat, poultry, seafood, and eggs thoroughly
- avoiding sushi containing raw fish
- washing raw vegetables thoroughly
- avoiding unpasteurized milk, soft cheeses, and alfalfa sprouts
Prevention of STIs includes:
- abstaining from sexual contact outside of a mutually monogamous relationship
- using latex condoms correctly and consistently
- avoiding blood-contaminated needles, razors, or other items
Precautions for preventing fetal exposure to HIV-infected maternal blood include avoiding: amniocentesis, fetal scalp blood sampling, premature rupturing of the fetal membranes.
Antibody — A blood protein produced in response to a specific foreign substance including bacteria, viruses, and parasites; the antibody destroys the organism, providing protection against disease.
Cesarean section; C-section — Incision through the abdominal and uterine walls to deliver the fetus.
Conjunctivitis — An inflammation of the eye that can be caused by gonorrhea or chlamydia.
Cytomegalovirus; CMV — A common human herpes virus that is normally not harmful but may cause severe complications if transmitted to a fetus.
Fifth disease — Erythema infectiosum; a common respiratory infection among children caused by parvovirus B19 that usually is not serious but can cause fetal complications.
Group B streptococcal (GBS) disease — A common bacterial infection that is potentially life-threatening if transmitted to a fetus during early pregnancy or birth.
Herpes simplex virus; HSV — A very common sexually transmitted infection; Type-2 HSV causes genital herpes and type-1 HSV usually causes cold sores but also can cause genital herpes; congenital HSV can be transmitted to the fetus during birth if the mother has an active infection.
Human papillomavirus (HPV) — A large family of viruses, some of which cause genital warts; HPV can be transmitted to a fetus during birth.
Immune globulin — Serum containing antibodies against a specific infection.
Listeriosis — A food-borne bacterial infection caused by Listeria monocytogenes to which pregnant women are particularly susceptible.
Meningitis — An inflammation of the membranes covering the brain and spinal cord that can be caused by various congenital infections.
Perinatal infection — A maternal infection that is transmitted to the fetus after membrane rupture or during labor or delivery.
Placenta — The uterine organ that provides nourishment to the fetus.
Prenatal infection — A maternal infection that is transmitted to the fetus through the placenta.
Rubella — German measles; three-day measles; a viral infection that causes death or severe birth defects if transmitted to the fetus during the first 10 weeks of gestation.
Salmonellosis — Food poisoning; an infection by bacteria of the genus Salmonella that usually causes severe diarrhea and may be transmitted to the fetus.
Sepsis — A systemic or body-wide response to infection.
Sexually transmitted infection; STI — An infectious disease that is transmitted through sexual activity.
Ultrasound — High-frequency sound waves that are used to visualize parts of the body or a fetus in the womb.
Varicella — Chickenpox; a disease caused by the Varicella zoster virus—human herpes virus 3—that can cause severe birth defects if transmitted to the fetus during the first 20 weeks of pregnancy and newborn complications if it is transmitted perinatally.
Prevention of maternal-to-fetal HSV transmission includes:
- abstaining from sexual activity during the last trimester of pregnancy or if there are signs of an outbreak or visible sores
- using a condom even if no symptoms are present
- postponing membrane rupture
- avoiding a fetal monitor that makes tiny punctures in the scalp
- avoiding vacuum or forceps deliveries which cause breaks in the infant's scalp
Creasy, Robert K., et al. Maternal-Fetal Medicine: Principles and Practices. 5th ed. London: W. B. Saunders, 2003.
MacLean, Allan, et al., editors. Infection and Pregnancy. London: Royal College of Obstetricians and Gynaecologists, 2001.
"Cytomegalovirus; Advances Made in Diagnosis of Maternal CMV Infection." Women's Health Weekly September 2, 2004: 51.
Lallemant, M., et al. "Single-dose Prenatal Nevirapine plus Standard Zidovudine to Prevent Mother-to-Child Transmission of HIV-1 in Thailand." New England Journal of Medicine 351, no. 3 (July 15, 2004): 217-28.
Montoya, J. G., and O. Liesenfeld. "Toxoplasmosis." Lancet 363, no. 9425 (June 12, 2004): 1965-76.
"Parasitology; Preventive Practices Eliminate the Risk for Congenital Toxoplasmosis." Health & Medicine Week May 3, 2004: 715.
American College of Obstetricians and Gynecologists. 409 12th St. SW, PO Box 96920, Washington, DC 20080-6920. 202-863-2518. http://www.acog.org.
American Social Health Association. PO Box 13827, Research Triangle Park, NC 27709-3827. 800-783-9877. http://www.ashastd.org.
Association of Women's Health, Obstetric and Neonatal Nurses. 2000 L Street NW, Suite 740, Washington, DC 20036. 800-673-8499. 202-261-2400. http://www.awhonn.org.
Centers for Disease Control and Prevention. 1600 Clifton Road, Atlanta, GA 30333. 888-232-3228. 〈http://www.cdc.gov〉.
Hepatitis B Foundation. 700 East Butler Avenue, Doylestown, PA 18901-3697. 215-489-4900. http://www.hepb.org.
March of Dimes Birth Defects Foundation. 1275 Mamaroneck Avenue, White Plains, NY 10605. http://www.marchofdimes.com.
Barss, Vanessa A. Patient Information: Avoiding Infections in Pregnancy. UpToDate Patient Information. January 11, 2002 [cited March 15, 2005]. http://patients.uptodate.com/topic.asp?file=pregnan/2251.
Cytomegalovirus (CMV) Infection. National Center for Infectious Diseases, CDC. October 26, 2002 [cited February 21, 2005]. http://www.cdc.gov/ncidod/diseases/cmv.htm.
"Genital Herpes." Health Matters. NIAID Fact Sheet. September 2003 [cited February 21, 2005]. http://www.niaid.nih.gov/factsheets/stdherp.htm.
"Gonorrhea." Health Matters. NIAID Fact Sheet. October 2004 [cited February 21, 2005]. http://www.niaid.nih.gov/factsheets/stdgon.htm.
"Group B Streptococcal Disease (GBS)." Disease Information. Division of Bacterial and Mycotic Diseases, CDC. February 11, 2004 [cited February 21, 2005]. http://www.cdc.gov/ncidod/dbmd/diseaseinfo/groupbstrep_g.htm.
Herpes Simplex and Pregnancy. International Herpes Alliance. [Cited February 21, 2005]. 〈http://www.herpesalliance.org/resources—04.htm〉.
"HIV and AIDS in Pregnancy." Professionals & Researchers. March of Dimes. November 2002 [cited February 22, 2005]. http://www.marchofdimes.com/professionals/681_1223.asp.
"HIV and Pregnancy." AIDSinfo. Health Information for Patients, U.S. Department of Health and Human Services. October 2004 [cited February 22, 2005]. http://aidsinfo.nih.gov/other/cbrochure/English/11_en.html.
"Human Papillomavirus and Genital Warts." Health Matters. NIAID Fact Sheet. July 2004 [cited February 21, 2005]. http://www.niaid.nih.gov/factsheets/stdhpv.htm.
Listeriosis and Pregnancy: What is Your Risk? Food Safety and Inspection Service, U.S. Department of Agriculture. September 2001 [cited March 16, 2005]. http://www.fsis.usda.gov/OA/pubs/lm_tearsheet.htm.
"Mother-To-Infant Transmission." Science. HIV Prevention Site, Division of AIDS, NIAID. May 21, 2002 [cited February 22, 2005]. http://www.niaid.nih.gov/daids/prevention/infant.htm.
Pregnancy and HIV. AIDS InfoNet. May 2, 2004 [cited March 16, 2005]. 〈http://www.aidsinfonet.org/en/doc/611.doc〉.
Pregnant Women and Hepatitis B. Hepatitis B Foundation. [Cited February 22, 2005]. 〈http://www.hepb.org/02-0068.hepb〉.
"STDs & Pregnancy." STD Prevention. National Center for HIV, SID and TB Prevention, CDC. [Cited February 22, 2005]. http://www.cdc.gov/STDFact-STDs&Pregnancy.htm.