Infections have historically been a major cause of maternal and fetal morbidity and mortality worldwide, and they remain so in the 21st century. Factors such as maternal serological status, timing of infection during pregnancy, mode of acquisition, and immunological status influence disease outcome.
Pregnancy-Induced Immunological Changes
Even after intensive study, many of the maternal immunological adaptations to pregnancy are not well elucidated (see Chap. 5, Immunological Functions). Some of the abnormal aspects of human immunity are considered in Chapter 54. And finally, factors dealing with the maternal-fetal interface that allow immunological tolerance of the fetus as a graft are discussed in Chapter 3, Immunological Considerations of the Fetal–Maternal Interface. Suffice it to say that these myriad changes also affect to a certain degree maternal response to infections. An understanding of fetal and newborn immunology is also imperative as the fetus is susceptible to many of these infections.
Fetal and Newborn Immunology
The active immunological capacity of the fetus and neonate is compromised compared with that of older children and adults. According to Stirrat (1991), fetal cell-mediated and humoral immunity begin to develop by 9 to 15 weeks. The primary fetal response to infection is immunoglobulin M (IgM). Passive immunity is provided by IgG transferred across the placenta. By 16 weeks, this transfer begins to increase rapidly, and by 26 weeks, fetal concentrations are equivalent to those of the mother. After birth, breast feeding is protective against some infections, although this protection begins to decline at 2 months of age (World Health Organization Collaborative Study Team, 2000).
Vertical transmission of infection refers to passage from the mother to her fetus of an infectious agent through the placenta, during labor or delivery, or by breast feeding. Thus, preterm rupture of membranes, prolonged labor, and obstetrical manipulations may increase the risk of neonatal infection. Those occurring less than 72 hours after delivery are usually caused by bacteria acquired in utero or during delivery, whereas infections after that time most likely were acquired afterward. Table 58-1 details specific infections by mode and timing of acquisition.
Table 58-1. Specific Causes of Some Fetal and Neonatal Infections |Favorite Table|Download (.pdf)
Table 58-1. Specific Causes of Some Fetal and Neonatal Infections
Viruses: varicella-zoster, Coxsackie, human parvovirus B19, rubella, cytomegalovirus, human immunodefi-ciency virus
Bacteria: listeria, syphilis, Borrelia
Protozoa: toxoplasmosis, malaria
Bacteria: group B streptococcus, coliforms
Viruses: herpes simplex
Bacteria: gonorrhea, chlamydia, group B streptococcus, tuberculosis, mycoplasmas
Viruses: herpes simplex, papillomavirus, human immunodeficiency virus, hepatitis B, hepatitis C
Bacteria: staphylococcus, coliforms
Viruses: herpes simplex, varicella zoster
Human transmission: staphylococcus, herpes simplex virus
Respirators and catheters: staphylococcus, coliforms
Neonatal infection, especially in its early stages, may be difficult to diagnose because neonates often fail to express classic clinical signs. If ...