Public Health Approach to Emerging Infections Among Pregnant Women

Abstract

As public health professionals respond to emerging infections, particular attention needs to be paid to pregnant women and their offspring. Pregnant women might be more susceptible to, or more severely affected by, emerging infections. The effects of a new maternal infection on the embryo or fetus are difficult to predict. Some medications recommended for prophylaxis or treatment could harm the embryo or fetus. We discuss the challenges of responding to emerging infections among pregnant women, and we propose strategies for overcoming these challenges.

Recent outbreaks of West Nile virus disease,1 severe acute respiratory syndrome,2 monkeypox,3 and anthrax,4 and concern over pandemic influenza5 and bioterrorism,6 highlight the importance of responding to emerging infections7 (defined as those for which the incidence has risen in the past 2 decades or threatens to rise in the near future).8 In developing response strategies, public health practitioners must consider the impact of strategies on pregnant women and their offspring,7^,9^–14 so that exposed women are appropriately advised and treated. We outlined challenges that public health professionals face regarding emerging infections in pregnant women and propose strategies for response (Table 1 ▶).

TABLE 1—

Emerging Infections Among Pregnant Women: Challenges and Proposed Public Health Response

Challenges	Response
Pregnant women could be more susceptible to infection or have increased morbidity and mortality from infection, because of altered immune response or physiological changes of pregnancy	Evaluate pregnancy as a potential risk factor for susceptibility to infection and for increased morbidity and mortality Develop specific recommendations to prevent and treat infection of pregnant women
Emerging infection in pregnant women could cause adverse effects in embryo or fetus, even when maternal infection is mild or asymptomatic	Educate health care providers about emerging infections, available diagnostic studies, preventive measures, and treatment Encourage health care providers to maintain a high index of suspicion for emerging infections when evaluating even mild symptoms in pregnant women; in some cases, screening of asymptomatic women may be indicated so that prophylaxis or early treatment can be provided
Prophylaxis and treatment of emerging infections may be contraindicated in pregnant women, because of potential adverse effects of vaccine or medication on embryo or fetus	Carefully weigh the benefits of prophylaxis and treatment of pregnant women against the potential risks to the embryo or fetus
Effects of emerging infection on embryo or fetus are often unknown and difficult to predict, based on previous experience with maternal infections, and can present long after birth	Consider a wide range of effects of emerging infection on embryo or fetus Initiate surveillance for effects of infections during pregnancy and continue well beyond the newborn period; consider a wide range of possible sequelae
Diagnosis of emerging infections in embryo, fetus, or infant is often difficult and is often dependent on obtaining appropriate specimens at critical time periods	Educate health care providers about appropriate diagnostic specimens and timing of collection

Increased susceptibility and risk for relapse or exacerbation of infections during pregnancy have been reported for several infections.15^–18 Pregnant women are also known to have increased morbidity and mortality from certain infections.19^–23 Thus, when risk factors for disease susceptibility and severity (e.g., age and presence of chronic conditions) are examined, pregnancy should be considered a potential factor. The development of recommendations for treatment and prophylaxis specific to pregnant women may need to be considered (e.g., influenza vaccination is recommended for women who will be pregnant during the influenza season because of increased morbidity and mortality during pregnancy).22

Because seemingly benign maternal infections can have serious consequences on the health of the embryo or fetus (hereafter referred to as “fetus”),24^,25 potential manifestations of infection in pregnant women should be carefully evaluated. Public health professionals should educate health care providers about emerging infections occurring in their area, available diagnostic testing, preventive measures, and treatment. Providers should be encouraged to have a high index of suspicion for emerging infections when evaluating symptoms in pregnant women. For some infections (e.g., HIV),26^,27 screening of asymptomatic women might be indicated to prevent or provide early treatment of congenital infection.

Certain vaccinations or medications are contraindicated during pregnancy because of their potential fetal effects.28 Fetal effects of most medications are not known.29 Benefits of the vaccine or medication to be used for prophylaxis or treatment need to be weighed against the potential risk to the fetus. For example, information on ciprofloxacin, the recommended antimicrobial for adult postexposure prophylaxis against Bacillus anthracis, during pregnancy is limited.30 However, given the high morbidity and mortality known to be associated with anthrax, the benefits of ciprofloxacin prophylaxis have been deemed to outweigh the potential risks in women with high-risk exposure.31

The effects of some infections are well known;25 however, for an emerging infection, diverse fetal effects of infection need to be considered. The risk for transmission from mother to fetus and the likelihood of adverse fetal effects can vary with the gestational timing of infection.32^,33 Fetal effects can vary depending on the infectious agent and include spontaneous abortions, preterm birth, intrauterine growth retardation, neonatal sepsis, birth defects, and developmental disabilities. Some congenital infections can cause later manifestations (e.g., hearing loss) in infants appearing normal at birth.33 Careful physical and developmental examination of infants born to infected women is essential, but it can be difficult to determine additional studies to be performed. Cardiac echocardiography, ophthalmologic examination, brain imaging, and hearing evaluation all could be considered, and surveillance for effects of congenital infections needs to continue beyond the newborn period.

Diagnosis of a new congenital infection can be difficult. New diagnostic assays developed for adults may need to be applied without data regarding their sensitivity and specificity for congenital infection. Microbial culture, nucleic acid amplification, and immunohistochemical staining can document infection, but sensitivity of these tests is limited. Detection of specific IgM in infant serum provides strong evidence of congenital infection.34 However, false-positive IgM results have been reported,35^,36 and infection early in pregnancy might not elicit a fetal IgM response.35^,37 Because maternal IgG in the infant’s circulation disappears by age 12 months, documenting increasing or persistent microbial-specific IgG several months after birth may indicate congenital infection.34^,35 Because health care providers might not be familiar with difficulties associated with diagnosis of congenital infection, public health professionals should provide training about appropriate diagnostic specimens and timing of specimen collection to diagnose an emerging infection.

As public health professionals deal with emerging infections, they must consider the impact of infectious agents on pregnant women and their offspring. A carefully planned public health approach, which includes input from individuals with expertise in pediatrics, obstetrics, and infectious diseases, will improve our ability to protect women and their offspring from adverse consequences associated with emerging infections.