Adherence to vitamin D prophylaxis was significantly lower in families with more than one child, with the presence of siblings being the only factor significantly associated with poor adherence (odds ratio 2.72, 95% confidence interval 1.25-5.92).
Key Findings
Results
Overall adherence to vitamin D supplementation was high, with 85% of infants receiving supplements at least four times per week.
241 caregivers completed the survey
Cross-sectional survey conducted between March 21 and April 30, 2023
Study population included infants aged 4 weeks to 12 months at Ca' Granda Hospital, Milan, Italy
Adherence was defined as administration at least four times per week
Results
Good adherence to vitamin D prophylaxis was significantly more frequent in families with one child compared to families with two or more children.
Good adherence was 91% in families with one child
Good adherence was 78% in families with two or more children
Multiple logistic regression was used to identify factors associated with poor adherence
Results
The presence of siblings was the only factor significantly associated with poor adherence to vitamin D supplementation in multivariable analysis.
Odds ratio for poor adherence with siblings present: 2.72 (95% confidence interval 1.25-5.92)
No associations were found with caregiver education, infant age, chronic disease, intercurrent illness, or time spent outdoors
Multiple logistic regression analysis controlled for demographic and household factors
Methods
The study investigated a broad range of demographic and household factors as potential determinants of vitamin D supplementation adherence.
Survey collected data on demographic data, health status, daily vitamin D3 administration frequency, and family characteristics
Factors examined included caregiver education, infant age, chronic disease, intercurrent illness, and time spent outdoors
None of these additional factors were significantly associated with poor adherence in multivariable analysis
Conclusions
The authors conclude that awareness of the association between family size and lower vitamin D adherence could inform counselling strategies and intervention design.
Findings suggest that families with multiple children may benefit from targeted counselling
The authors recommend this association be considered in designing interventions to sustain adherence
Study was a cross-sectional survey design conducted at a single hospital in Milan, Italy
Panicola M, Cereghetti G, Agostoni C, Alberti I, Vassilopoulou E, Bettocchi S, et al.. (2026). Lower Adherence to Vitamin D Prophylaxis in Families With Multiple Children.. Acta paediatrica (Oslo, Norway : 1992). https://doi.org/10.1111/apa.70435