Infections and Recurrent Miscarriage

a blog by Joseph A. Hill, III, MD, Fertility Centers of New England, August 27, 2010

Infection of the reproductive tract has been linked to pregnancy loss, but there is not strong evidence in support of infections being a cause of recurrent loss.

Mycoplasma, ureaplasma, chlamydia, and Group B streptococcus have been extensively studied. Bacterial vaginosis has also been associated with losses after 12 weeks of gestation. However, the results of a large prospective study involving 70 patients with recurrent loss found no correlation with present or past infection with any of these bacteria.

Certain viruses have also been associated with pregnancy loss, including herpes simplex virus (HSV) and human cytomegalovirus (CMV), which may directly infect the placenta. These viruses may be involved in intrauterine growth restriction, premature rupture of membranes, and preterm birth, but their role in recurrent miscarriage remains speculative.

An inflammatory condition known as endometritis, which is inflammation of the endometrium or uterine lining, has also been associated with both infertility and recurrent pregnancy loss. Endometritis can be caused by a recent or past infection. It may also occur (in rare instances) after pregnancy loss or a procedure such as a D&C or D&E.

Whether chronic infection is a cause of recurrent pregnancy loss is not precisely known. An individual’s susceptibility to an infectious organism may be the determining factor in whether pregnancy loss occurs. Other probable factors include:

• primary exposure to an infection during early pregnancy
• capability of the infection to cause uterine and placental infection
• development of an infectious state, and
• immunocompromise of the person infected

It is known that infection causing fevers over 102 degrees Fahrenheit can potentially kill embryos and destroy early pregnancies. Therefore measures to decrease the likelihood of a high fever (taking acetaminophen), even in illnesses like influenza, are important in those attempting pregnancy and during early pregnancy.