Introduction

Pregnancy is a vulnerable period for the acquisition of infections and infectious diseases. Not only can the pregnant woman herself become infected, but fetal and/or neonatal transmission may also occur. Although pregnancy does not usually affect the incidence and severity of infections, some physiological adaptations of pregnancy can result in increased risk for some infections particularly urinary tract infections, pneumonia and chorioamnionitis. In addition to maternal sequelae, the developing fetus is often placed at risk secondary to hyperpyrexia, hypoxia, preterm labour and congenital infection. The number of maternal infections known to be associated with adverse pregnancy outcomes continues to increase. Adverse pregnancy outcomes can be a direct consequence of fetal or neonatal infection or an indirect effect secondary to vaginal, cervical or intrauterine infections. Specific fetal risks are highly dependent on the causal organism, potential for transplacental passage, timing of exposure and maternal/ fetal immune status. Adverse outcomes associated with maternal infection during pregnancy are varied and include infertility, ectopic pregnancy, miscarriage, congenital anomalies, stillbirth, intrauterine growth retardation, preterm delivery, neonatal death, and long-term disability of the infant.

Maternal infection and pregnancy

Infections are common during pregnancy, but the risks associated with infections vary by pathogen and disease site (Alexander, 1984). Infections such as acute cystitis, upper respiratory viral infections and trichomoniasis are generally of concern for maternal health but pose less risk to the fetus. In contrast, infections such as cytomegalovirus (CMV), genital herpes simplex virus (HSV), parvovirus, and rubella can lead to significant fetal morbidity/mortality but have little or no maternal sequelae. Similarly, relatively innocuous constituents of the genital and rectal flora, such as group B streptococcus (Streptococcus agalactica) and Escherichia coli, may represent benign maternal colonization.