Perinatal Infections: What You Need to Know

Frederick R. Jelovsek MD

For years, doctors have routinely screened pregnant women for infections which affect the outcome of the pregnancy or cause birth defects in the baby. Gonorrhea and chlamydia are checked for with cervical smears and syphilis is assessed using a blood test. Each of these STDs can cause a problem in the newborn with eye infections and even congenital structural defects for syphilis. Hepatitis and HIV are other viral diseases that mainly are transmitted to the baby during birth so it is useful to know if they are present so that newborn infections can be prevented. There are other infections in pregnancy, however, that are frequently associated with preterm labor - bacterial vaginosis, group B streptococcus, urinary tract infections, trichomonas and mycoplasma hominis. Doctors are checking for these infections much more frequently now because of the serious impact that prematurity can make in a baby's survival. Approximately 80% of women undergoing preterm labor have one or more of these infections going on.

What signs and symptoms are present when these perinatal infections are present?

Burning urination and urinary frequency are signs of lower urinary tract infections. Vaginal discharge may also be a sign of infection especially if the discharge is any color other than clear or white or if there is an odor present spontaneously or with sexual relations. Many women are unaware that vaginal bleeding during pregnancy is also associated with vaginal infections.

In a study by French JI et al: Gestational bleeding, bacterial vaginosis, and common reproductive tract infections: Risk for preterm birth and benefit of treatment. Obstet Gynecol 1999;93:715-24, the authors found an 11% incidence of 1st trimester bleeding, 6.4% in the second trimester and 4.1% in the third trimester. By analysis, each of the infections of trichomonas, Chlamydia, and bacterial vaginosis, were associated with bleeding problems; group B streptococcal was not. In women with vaginal bleeding during pregnancy, 44% had bacterial vaginosis and 82% had positive cultures for ureaplasma urealyticum. Antibiotic treatment of infections when they were found antenatally resulted in a 50% reduction in the rate of preterm labor.

I have heard that Group B strep can cause death in newborn infants. Will my doctor check me for it?

Group B strep is often associated with premature rupture of the membranes (broken bag of waters). A newborn can acquire group B Strep during labor and delivery and rarely die from the blood born sepsis it causes. Group B strep is extremely difficult to eradicate, however, so that it is not recommended to treat in early pregnancy because most infections come back. Rather, it is recommended to screen women who have had a previous pregnancy with a Group B strep infection, a history of a stillborn or neonatal death, or premature rupture of the membranes in the current pregnancy. Some doctors will also screen women with vaginal and rectal cultures for group B strep at 35-36 weeks of pregnancy and treat those women who are positive during labor and delivery. Penicillin or cephalosporin antibiotics are the treatments of choice.

What It Means To Have An Infection

How bad is it to have urinary tract infections in pregnancy?

Urinary tract infections lead to preterm labor as well as increase the risk for infections that ascend into the kidney, pyleonephritis, and may cause permanent kidney damage. From 3-10% of women have urinary tract infections in pregnancy and most of these are preceded by bacteria in the urine without any symptoms (asymptomatic bactiuria). Most screening tests in pregnancy are designed pick up asymptomatic bactiuria and treat it before it even becomes a UTI, much less a serious pyleonephritis. If a woman does have a pyleonephritis infection during pregnancy, she needs a kidney Xray after delivery to look for congenital anomalies of the urological tract. If the infection does not clear with adequate treatment in pregnancy imaging studies may need to be done during pregnancy to rule out any renal abscesses that do not clear up.

Do other types of vaginal infections cause harm to the baby?

Yeast vaginitis does not seem to cause a problem producing preterm labor or an infection in the newborn. Trichomonas is associated with bleeding and preterm labor as was previously mentioned. A little heard of, but very common infection is mycoplasma hominis, mycoplasma genitalium and ureaplasma urealyticum. They can be cultured so frequently from the vagina and cervix that there is sometimes a question as to whether they really cause a problem. It may have do do with the amount of bacterial load rather than the presence of them that is important. Erythromycin is the treatment of choice for mycoplasma genitalium and ureaplasma urealyticum which are probably the infections to be concerned about. Not enough is known about these and doctors do not routinely culture for them. So unless there is a past history of preterm labor or delivery, it is uncertain to what degree these are clinically important.

What if I have HPV - venereal warts? Will my baby get it?

You cannot diagnose human papilloma virus infection by Pap smear. You can suspect it, but the diagnosis is by DNA sequence subtyping of cervicovaginal smears. The incidence of positivity is 20-30% in all women delivering infants but if one considers historical infections and earlier in pregnancy testing, the overall incidence in the population is about 75%. Studies have shown anywhere from a 3% to a 37% transmission rate to the infant. There is less colonization of newborns when delivery is by C-Section (27%) than by vaginal delivery (51%), but the incidence of a newborn getting an active infection or a bad disease like laryngeal cord papillomas is extremely small. Most doctors consider the infant culture data evidence of contamination when the baby is delivered rather than infection since the positivity of the infant decreases over several months.

There are no current recommendations to alter delivery based on having signs or laboratory studies showing and HPV infection.

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