Breastfeeding Is Associated with Decreased Hospitalization for Neonatal Fever

Introduction

Breastfeeding provides optimal nutrition during the early months of life. Based on evidence in both developed and developing countries, it is the recommended standard for newborns and infants.^1–4 The World Health Organization and the American Academy of Pediatrics recommend 6 months of exclusive breastfeeding.^3,5 Less than optimal rates of breastfeeding are likely to result in health risks for this population, including increased hospitalization. ⁶

Both duration and exclusivity contribute to the health benefits of breastfeeding. ⁷ Infants who are fully breastfed for 4–6 months have significantly fewer hospitalizations due to infectious causes during the first year of life. ⁶ This protective effect has been reported in particular for respiratory infections (including middle ear) as well as gastrointestinal infections.^8–11 Furthermore, breastfed children with infections tend to have a milder course of illness. ¹²

Fever during the first month of life (neonatal fever, NF) may be the sole presenting sign of many potentially life-threatening infections. Infants less than 1 month of age are routinely hospitalized and undergo extensive and invasive testing to determine the source of fever and are almost always treated with antibiotics until a bacterial infection is ruled out. ¹³ While most cases ultimately prove benign, current management of NF is associated with increased infant stress, ¹⁴ parental anxiety,^15,16 and a financial burden on health system resources. In this study, we examined the association between hospitalization due to NF and type of feeding during the first month after birth.

Materials and Methods

This retrospective case–control study examined all children hospitalized for NF at the Carmel Medical Center between January 2006 and December 2009. Cases included full-term infants who were healthy at birth, discharged home, and were subsequently hospitalized before the age of 1 month due to fever. Fever was defined by a rectal temperature ≥38°C, measured either at home or in the emergency room. Controls were date-of-birth matched, healthy full-term children who were born in the study hospital, but not hospitalized during the first month of life. Matching by date of birth controlled for seasonality and recall bias. A priori exclusion criteria for both cases and controls included birth outside of a hospital, any significant antenatal or perinatal pathology, or birth weight under 2 kg. In addition, infants of parents who could not be contacted or could not recall early feeding history were not enrolled.

Following verbal informed consent, a short, structured parental telephone interview was conducted during 2010 inquiring about the feeding history in the first month of life and other known risk factors for infections during infancy, for example, household smoking habits and crowding. ¹⁷ Because of the time elapsed, we asked only as to the predominant type of feeding, and for women who reported that the infant had received formula, how many feeds per day on an average. Parents were not questioned as to other details such as volumes, frequency, duration, etc. Since the cases and controls were matched by date of birth, we assume that the recall bias was similar in both groups. For patients, additional information was collected from the child's medical record regarding admission age, length of hospitalization, and clinical diagnosis. Controls were asked whether there had been any hospitalizations to ascertain that the infant had not been hospitalized elsewhere. Two feeding categories were used: (1) exclusive or predominant breastfeeding (up to one nonbreast milk feeding a day), and (2) partial breastfeeding (more than one nonbreast milk feeding a day) or formula fed. A positive response to questions regarding maternal, paternal, or other family members smoking at home was categorized as a positive exposure to household smoke. A crowding index (a surrogate for socioeconomic status) was calculated from the number of persons in the household divided by the number of rooms. These were then divided into quartiles with the lowest quartile having the least number of persons per room in the home. We note that this calculated crowding index is one component of socioeconomic status as measured by the Israel Bureau of Statistics.

Statistical analysis was performed using the SPSS statistical analysis package (version 21; SPSS, Inc., Chicago, IL). Categorical information was evaluated using the Pearson's Chi square test. Length of hospitalization was assessed by Student's t-test. Adjusted odds ratios were calculated using logistic regression. A 95% confidence interval (CI) is reported.

The study was approved by the institutional ethics review board of the Carmel Medical Center.

Results

During the study period, 180 neonates were hospitalized in our center with NF. The parents of 141 infants (76 male, 64 female) agreed to participate in the study. The main reason for nonparticipation was inability to locate. One girl in the hospitalized group was diagnosed with a congenital cardiac anomaly and was excluded from further analysis, leaving 140 cases. One hundred twenty nine controls (67 male, 62 female) were matched and enrolled. We ceased to locate controls after contacting 129 when it became clear that the difference between cases and controls with regard to feeding type was very significant. The male: female ratios of both groups (1.19, 1.08) were not significantly different (Table 1). Median age at the time of hospitalization was 20 days (range 2–30 days), with a median in-hospital stay of 4 days (range 2–11 days). In 24 of 140 (17%), a probable source of fever was identified, including the following: urinary tract infection (n = 14), bronchiolitis (n = 10), and acute otitis media (n = 5). One infant had concomitant tympanocentesis-proven pneumococcal acute otitis media and pneumococcal bacteremia. No cause of fever was found for the remaining 116 infants.

Overall at the age of l month, 160 (66.7%) infants were exclusively breastfed, 9 (3.8%) received up to one formula feeding a day, 51 (21.3%) were fed more than one formula feeding a day, and 49 (20.4%) were only formula fed. Since the number of children fed up to one formula feeding a day was so small, this group was merged with the exclusive breastfeeding group. More infants in the hospitalized group were formula or partially breastfed compared to control healthy infants (66.0% and 34.0%, respectively, p < 0.001). Hospitalized children had a 2.5-fold increased risk of not being exclusively or predominantly breastfed (odds ratio = 2.49, 95% CI 1.49, 4.16). Hospitalized infants also had a higher prevalence of any exposure to household smoke than controls (64.7% and 35.3%, respectively, p < 0.001). Multivariate logistic regression analysis showed that the associations between hospitalization and formula/partial breastfeeding or any exposure to household smoke were independently significant and did not change after controlling for gender and crowding index (Table 2). In the patient group, there was no correlation between type of feeding and length of hospitalization.

Discussion

Breastfeeding is the recommended method for feeding infants. It promotes health by protecting newborns and infants from infectious diseases ¹⁸ as well as providing nutritional, developmental, emotional, social, and financial benefits. ¹⁹ This study examined the association between breastfeeding and hospitalization due to NF. Infants hospitalized with NF were 2.5 times more likely to have been formula or partially breastfed than matched, healthy control infants. While some studies have emphasized the significance of exclusive breastfeeding in conferring protection from infection, ²⁰ a protective effect was seen also for infants receiving predominant breastfeeding, but not for those partially breastfed or formula fed. This effect remained significant even after controlling for exposure to smoke and household crowding. The independent association of household smoke with hospitalization for NF found in this study is not surprising, considering the extensive evidence on the effect of exposure to passive smoke and infection in infants. ²¹

NF is a nonspecific presenting sign of many potentially grave conditions, including sepsis and meningitis. ²² The underlying causes of NF are predominantly viral, but also include bacterial infection such as urinary tract infection, bacteremia, meningitis, pneumonia, and gastroenteritis. Early diagnosis is paramount to minimizing morbidity and mortality during this first month of life and compels parents and healthcare providers to seriously address any sign of illness. Previous studies have shown that the protective effect of breastfeeding on the incidence of infection in infants usually lasts for up to 1 year of age.^5–8 Our data suggest that breastfeeding provides significant protection as early as the first month of life.

Hospitalization for NF has the potential for a substantial deleterious impact on the well-being of an infant and his/her parents, as well as incurring considerable direct and indirect costs.^23,24 NF requires extensive and invasive testing to identify its cause and neonates are given empiric intravenous antibiotic therapy until cultures prove negative (2–3 days). ¹² NF is sufficiently common that considerable efforts have been invested to try and reduce the number of children requiring a complete evaluation for sepsis and hospitalization.^25,26 Although in most cases, a bacterial cause is not identified,^27,28 diagnostic and therapeutic procedures such as lumbar puncture, invasive urine sampling, phlebotomy, and intravenous catheter insertion cause substantial pain and stress to the infant and anxiety to parents.^14–16 By reducing the risk of hospitalization due to NF, breastfeeding promotes both infant and family well-being and decreases health-related expenditures.

Compliance with the recommendation for exclusive breastfeeding for 6 months is highly desirable. Data show that this goal has not been attained; currently only 49% of U.S. infants are breastfed at 6 months of age, while 16.4% are exclusively breastfed. ²⁹ Paricio Talayero et al. estimate that full breastfeeding for 4 months or more prevents more than half of the hospitalizations due to nonperinatal infections in infants up to 1 year. ⁶ Breastfeeding in infancy has been reported to reduce the degree of hypoxia and malnutrition in hospitalized infants 0–6 months of age with pneumonia and diarrhea. ³⁰ This study provides evidence of health benefits of exclusive and predominant breastfeeding during the first month of life in a resource-rich country. This adds to known benefits, usually assessed after several months.

Conclusion

This study demonstrates that exclusive or predominant breastfeeding of infants less than 1 month of age and a smoke-free home independently reduce the risk of NF-related hospitalization by over two-fold. The retrospective, single site design of the study requires cautious interpretation. Prospective, multiple-site, larger studies, which would preclude recall bias, are needed to determine whether breastfeeding during the first month of life and a smoke-free home are associated with a decreased risk of NF, the need for diagnostic evaluation, and inpatient therapy.