Kazushige Ikeda

To determine safety and efficacy of exclusive human milk diet (EHMD) for very low birth weight (VLBW, <1500 g) infants. Prospective, controlled, open trial of VLBW infants randomized to EHMD (mother's own milk [MOM]/donor milk [DM] with human milk-based fortifiers) or Standard Diet (MOM/DM with cow milk-based fortifier/formula). Outcomes included superiority of weight gain velocity from birth to 34 weeks gestational age, time to full feeds, and safety. In total, 147 infants received EHMD (n = 77) or Standard Diet (n = 70). The EHMD group had superior mean weight gain velocity versus the Standard Diet (13.44 vs 11.96 g/kg/day, p = 0.006) and earlier mean time to full feeds (20.0 vs 25.9 days, p = 0.03); adverse events were not significantly different (32.5% vs 21.4%, p = 0.13). EHMD is viable for management of VLBW infants, providing improved growth without reduced safety. Japan Registry of Clinical Trials: jRCT2031210384.

In Japanese infants aged ≤12 months at risk for severe RSV-associated lower respiratory tract infections who received two doses of nirsevimab 5–6 months apart, no safety concerns or anti-drug antibodies occurred. Nirsevimab serum concentrations were consistent with those previously demonstrated to be efficacious in healthy preterm and term infants.

Vitamin D (VD) status is assessed by measuring serum 25-hydroxyvitamin D (25(OH)D) levels using immunoassays. In December 2024, a Japanese diagnostic laboratory transitioned from chemiluminescent immunoassay (CLIA: LIAISON® 25 OH Vitamin D Total Assay) to an electrochemiluminescent immunoassay (ECLIA: Elecsys® Vitamin D Total III assay). Although these methods yield comparable results in adults, it remains unclear whether this applies to children, particularly newborns and infants. This study aims to clarify the impact of transition from CLIA to ECLIA on 25(OH)D levels during early infancy. Serum 25(OH)D levels were measured in 84 infants under three months old (67 under four days old) using both CLIA and ECLIA. Correlation and agreement were assessed using Passing–Bablok regression and Bland–Altman analyses, respectively. The obtained regression equation was applied to 252 age- and sex-matched cases from 2,253 historical controls in the registry to evaluate changes in VD classification. The regression equation was YECLIA = 0.846XCLIA – 2.281 (τ = 0.53, p < 0.001). Bland–Altman analysis revealed a constant negative bias of –4.89 ± 3.53 ng/mL [–5.66, –4.12] (mean ± standard deviation [95% confidence interval]) for ECLIA versus CLIA. Reclassification revealed an increase in VD deficiency (25(OH)D < 12 ng/mL) from 27.8% to 61.9%, and VD insufficiency (25(OH)D < 20 ng/mL) from 75.4% to 91.7%. The transition from CLIA to ECLIA led to lower measured 25(OH)D levels in newborns and infants and increased VD deficiency and insufficiency diagnoses. Method-specific differences should be considered when evaluating VD status during early infancy, particularly in infants under four days.

Respiratory syncytial virus (RSV) is a leading cause of hospitalization in infants and young children worldwide. Although most RSV hospitalizations occur at secondary hospitals, information on RSV-related healthcare costs in these settings is limited. A retrospective analysis of RSV-related hospitalizations was conducted at Saitama City Hospital, a secondary hospital, between April 2018 and May 2024. Patients with laboratory-confirmed RSV infection were included. The study period was divided into three phases based on revisions of the national medical reimbursement schedule. Hospitalization costs were calculated, and high-cost outliers were identified using the interquartile range (IQR) method. A total of 345 patients were hospitalized for RSV, with a marked reduction in Phase II admissions corresponding to the early COVID-19 pandemic. Median hospitalization costs per episode increased in all three phases, from JPY 318,930 to JPY 393,930. Eighteen admissions were identified as cost outliers and classified into three subgroups: (1) children with airway or neurologic disorders, often older than 24 months; (2) otherwise healthy infants under 12 months; and (3) children eligible for palivizumab who contracted RSV before or after the recommended prophylaxis period. Our findings emphasize the existence of high-cost RSV cases outside the currently recognized high-risk groups, including older children with chronic airway disease and healthy young infants. Clinical burden and healthcare costs may be reduced by refining prophylaxis strategies and early intervention in Japan.

Vitamin D (VD) insufficiency in pregnant women is a serious health problem worldwide. To prevent VD insufficiency during pregnancy, several guidelines recommend 600 IU/day VD for all pregnant women. In Japan, no national guidelines for preventing VD insufficiency have been implemented, and no study has evaluated adequate VD intake in pregnant women; however, the number of pregnant women taking commercial dietary supplements containing VD has increased in recent years. This study aimed to examine the effects of maternal commercial supplementation of VD on 25-hydroxyvitamin D (25(OH)D) levels in newborns. We retrospectively analyzed the serum 25(OH)D levels in 279 four-days-old newborns born at the Saitama City Hospital from 2022 to 2023. Newborns were classified into a supplement group (mothers who took VD-containing commercial supplements regularly throughout pregnancy; n = 103) and a non-supplement group (mothers who did not take any supplements during pregnancy; n = 176). The study findings revealed that serum 25(OH)D levels in newborns in the supplement group were higher than those in the non-supplement group (median [interquartile range]: supplement group 17.2 [14.6, 22.9] vs. non-supplement group 14.3 [11.6, 16.7], p < 0.001). In the supplement group, approximately 70% of newborns still showed VD insufficiency. Although the maternal use of VD-containing commercial supplements during pregnancy increased the serum 25(OH)D levels in newborns at four days of age, additional measures, such as VD supplementation for newborns, are needed to improve neonatal VD status.