Postnatal Cytomegalovirus Infection of Preterm and Very-low-birth-weight Infants Through Maternal Breast Milk: Does It Matter?

Postnatally acquired cytomegalovirus infection among preterm infants

PURPOSE OF REVIEW

Although there are multiple benefits of mother's own milk feeding for very-low birth weight, low gestation infants, those born to cytomegalovirus (CMV)-seropositive mothers are at risk for acquiring postnatal CMV infection. This review will describe the risk and consequences of postnatal CMV infection among very preterm infants.

RECENT FINDINGS

Postnatal CMV may manifest as clinically silent infection or as mild to severe and occasionally fatal disease. The risk of disease is balanced by the health benefits of human milk feeding to preterm infants. Postnatal CMV infection has been associated with increased risks of multiple preterm morbidities such as bronchopulmonary dysplasia, necrotizing enterocolitis and neurodevelopmental impairment, but current evidence is limited by the selection bias inherent to reporting in case series and retrospective cohort studies.

SUMMARY

Knowledge gaps exist regarding the risk-benefit balance of pasteurization to inactivate CMV in fresh breast milk, as well as the optimal dosing, duration and efficacy of treating infected infants with antiviral medications. Multicenter, prospective studies are urgently needed to accurately determine the true burden that postnatal CMV infection presents to very preterm infants. Such studies will inform the need for preventive strategies and treatment guidance.

Association between viral infection and bronchopulmonary dysplasia in preterm infants: a systematic review and meta-analysis

Bronchopulmonary dysplasia (BPD) is the most common serious complication of very preterm infants (VPI) or very low birth weight (VLBW) infants. Studies implicate viral infections in etiopathogenesis. The aim of this study was to summarize the relationship between viral infections and BPD through a systematic review and meta-analysis. We searched PubMed, Embase, the Web of Science Core Collection, and the Cochrane Database on December 19, 2023. We included observational studies that examined the association between viral infections and BPD in preterm infants. We extracted data on study methods, participant characteristics, exposure assessment, and outcome measures. We assessed study risk of bias using the Newcastle-Ottawa Scale (NOS). We included 17 and 15 studies in the qualitative review and meta-analysis, respectively. The meta-analysis showed a significant association between viral infection and BPD diagnosed at 36 weeks postmenstrual age (odds ratio (OR): 2.42, 95% confidence interval: 1.89-3.09, 13 studies, very low certainty of evidence). In a subgroup analysis of specific viruses, cytomegalovirus (CMV) proved to be significantly associated with BPD diagnosed at 36 weeks postmenstrual age (OR: 2.34, 95% confidence interval: 1.80-3.05, 11 studies). We did not find an association between viral infection and BPD diagnosed on the 28th day of life, probably due to the small sample size of the included prospective studies.  Conclusion: Viral infections, especially CMV, are associated with an increased risk of BPD in preterm infants. Methodologically reliable prospective studies with large samples are needed to validate our conclusions, and high-quality randomized controlled studies are needed to explore the effect of prevention or treatment of viral infections on the incidence of BPD. What is Known: • Studies have attempted to identify viral infections and bronchopulmonary dysplasia in preterm infants; however, results have been inconsistent. What is New: • Systematic demonstration that viral infections, particularly cytomegalovirus, are positively associated with bronchopulmonary dysplasia diagnosed in preterm infants at the 36th week of postmenstrual age. • The importance of screening for viral infections in preterm infants, especially cytomegalovirus. More high-quality studies should be produced in the future to investigate the causal relationship between viral infections and bronchopulmonary dysplasia.

Human cytomegalovirus and neonatal infection

Human cytomegalovirus is an ancient virus that has co-evolved with humans. It establishes a life-long infection in suspectable individuals for which there is no vaccination or cure. The virus can be transmitted to a developing fetus in seropositive pregnant women, and it is the leading cause of congenital infectious disease. While the majority of infected infants remain asymptomatic at birth, congenital cytomegalovirus infection can lead to substantial long-term neurodevelopmental impairments in survivors, resulting in considerable economic and social hardships. Recent discoveries regarding cytomegalovirus pathophysiology and viral replication cycles might enable the development of innovative diagnostics and therapeutics, including an effective vaccine. This Review will detail our understanding of human cytomegalovirus infection, with an in-depth discussion regarding the viral genome and transcriptome that contributes to its pathophysiology. The neonate's clinical course will also be highlighted, including maternal and neonatal testing, treatment recommendations, and long-term outcomes.

Cytomegalovirus in Pregnancy

Cytomegalovirus is a pervasive DNA herpesvirus that, while clinically insignificant to an immunocompetent adult host, can cause significant morbidity to a congenitally infected fetus. Although detection is often possible with several common ultrasonographic markers and good diagnostic accuracy using polymerase chain reaction testing of amniotic fluid, there are no proven prenatal prevention or antenatal treatment options. Therefore, universal screening is not currently recommended in pregnancy. Strategies that have been studied in the past include immunoglobulins, antivirals, and the development of a vaccine. In this review, we will further discuss the themes above, along with future direction for prevention and treatment.

Minimal adverse outcomes of postnatal cytomegalovirus infection in term or moderate and late preterm infants

OBJECTIVE

The aim of study was to investigate at what extent breastfeeding and vaginal delivery can increase mother-to-child transmission of cytomegalovirus (CMV) and to observe the clinical outcomes of postnatal infection in term or moderate and late preterm infants.

METHODS

In this retrospective study of prospectively collected clinical data and serum samples, during 2012-2015, 380 women with CMV IgG positive/IgM negative and their 384 infants (4 twin pairs) with gestational age ≥32 weeks were included. CMV IgG and IgM were measured with enzyme-linked immunosorbent assay.

RESULTS

Of 384 infants followed up at 10.2 ± 2.3 months age, 177 (46.1%) were defined with CMV infection based on the presence of higher CMV IgG levels than in their mothers. The infection rate in 190 breastfed infants was higher than in 194 formula-fed infants (62.6% vs. 29.9%, P < 0.001). Vaginally delivered infants (172) had higher CMV infection rate than 212 infants delivered by caesarean section (55.2% vs. 38.7%, P = 0.001). Compared with formula feeding and caesarean section, breastfeeding and vaginal delivery increased postnatal CMV infection respectively (OR = 3.801, 95% CI 2.474-5.840, P < 0.001; OR = 1.818, 95% CI 1.182-2.796, P = 0.007). Nevertheless, compared to uninfected infants, CMV-infected infants had comparable height and body weight and showed no adverse effect on the liver enzymes.

CONCLUSION

Breastfeeding and vaginal delivery can increase postnatal CMV infection; however, the infection does not influence the growth of the term infants or preterm infants with gestational age ≥32 weeks. Thus, breastfeeding should be encouraged in these infants regardless of maternal CMV IgG status.

Perinatal Cytomegalovirus Infection

PURPOSE OF REVIEW

There have been recent advances in the field of congenital CMV infection (cCMV) related to antiviral treatment of pregnant women and infants, the implementation of newborn CMV screening programs, and the frequency and diagnosis of complications among infected children. In addition, postnatal CMV infection (pCMV) is increasingly recognized as a potential cause of long-term sequelae in addition to acute complications among preterm infants, raising important questions related to treatment, and prevention.

RECENT FINDINGS

High-dose valacyclovir appears to be safe and effective for the prevention of cCMV among women with first-trimester primary CMV infection. New studies reveal high rates of vestibular dysfunction and neuropsychiatric manifestations among children with cCMV. Some studies report associations between pCMV and long-term consequences, including neurodevelopmental delay and bronchopulmonary dysplasia, among very low birth weight infants, in addition to high risk of sepsis and death acutely, which has motivated efforts to eliminate the virus from breast milk by different methods.

SUMMARY

More long-term complications of cCMV are increasingly recognized among children previously thought to be asymptomatic. Although a preventive CMV vaccine may be achievable, strategies to reduce the burden of cCMV disease include maternal education about risk-reduction behaviors, antiviral treatment of pregnant women with primary infection, and newborn screening to allow timely, appropriate care. Similarly, although it remains unclear if pCMV causes long-term problems, there is growing interest in identifying and preventing disease from CMV infections among preterm infants.