J Korean Med Sci.  2020 Mar;35(8):e32. 10.3346/jkms.2020.35.e32.

Relationship between Breastfeeding, Birth History, and Acute Pyelonephritis in Infants

• Lee YJ
• Kim KM
• Jung HL
• Shim JY
• Kim DS
• Shim JW

• KMID: 2471052
• DOI: http://doi.org/10.3346/jkms.2020.35.e32

Abstract

BACKGROUND
Although the clinical importance of the immunological benefits of breastfeeding has been emphasized for decades, their direct relationship with acute pyelonephritis (APN) is still not clear. Our goal was to determine whether breastfeeding truly provides protection against APNs, while investigating the effects of other factors such as sex, age, mode of delivery, and birth weight on APN.
METHODS
A total of 62 infants under 6 months of age who had both microbiologically and radiologically-confirmed APN were enrolled in the case group. Healthy infants (n = 178) who visited the hospital for scheduled vaccinations were enrolled in the control group. The following participant characteristics were compared between the case and control groups: age, sex, birth order among siblings, feeding methods, weight percentile by month, birth weight percentile by gestational age, gestational age at birth, and mode of delivery.
RESULTS
Babies exclusively fed with manufactured infant formulae before 6 months of age had significantly higher risk for APN than breastfed or mixed-fed infants (odds ratio [OR], 3.4; 95% confidence interval [CI], 1.687-7.031; P = 0.001). Firstborn babies had lower risk for APN than 2nd- or 3rd-born babies (OR, 0.43; 95% CI, 0.210-0.919). Other factors that increased the risk for APN were low birth weight percentiles (OR, 8.33; 95% CI, 2.300-30.166) and birth via caesarean section (OR, 2.32; 95% CI, 1.097-4.887). There were more preterm births in the case group (10.9% vs. 1.7%; P = 0.002), but this did not increase the risk for APN (OR, 4.47; P = 0.063).
CONCLUSION
Feeding exclusively with formula before 6 months of age was related to higher risk for APN, which demonstrates that breastfeeding has a protective effect against APN. The other risk factors for APN were birth order (≥ 2nd-born), low birth weight, and birth via caesarean section.

Keyword

Breastfeeding; Urinary Tract Infections; Pyelonephritis; Low Birth Weight; Caesarean Section; Infants

MeSH Terms

Birth Order
Birth Weight
Breast Feeding*
Cesarean Section
Feeding Methods
Female
Gestational Age
Humans
Infant Formula
Infant*
Infant, Low Birth Weight
Infant, Newborn
Parturition*
Pregnancy
Premature Birth
Pyelonephritis*
Reproductive History*
Risk Factors
Siblings
Urinary Tract Infections
Vaccination