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Seasonality of births and childhood inflammatory bowel disease
Miroslav Mikulecký1, Iveta Cierna
11st Medical Clinic, Teaching Hospital, Comenius University, Bratislava, Slovak Republic. biometrik@pobox.sk
Insights
Children with Crohn disease show a seasonal birth pattern, with more births in summer, similar to type 1 diabetes. This suggests a potential environmental link to autoimmune conditions in Slovak children.
Area of Science:
- Pediatric autoimmune disorders
- Epidemiology of chronic diseases
- Seasonal birth patterns
Background:
- Type 1 diabetes in children exhibits seasonal birth variations in certain regions, with higher incidence in summer.
- Inflammatory bowel disease (IBD) is a group of autoimmune disorders affecting the gastrointestinal tract.
- Understanding birth seasonality may offer insights into environmental factors influencing IBD development.
Purpose of the Study:
- To investigate if a seasonal birth pattern exists for pediatric inflammatory bowel disease (IBD) in Slovakia.
- To compare the birth seasonality of Crohn disease and ulcerative colitis with that of type 1 diabetes.
Main Methods:
- Birth month data collected for children diagnosed with Crohn disease and ulcerative colitis.
- Birth data normalized for month length and population, then transformed into moving averages.
- Statistical analysis using cosinor regression to detect significant seasonal variations in birth rates.
Main Results:
- Crohn disease births showed a significant peak from June to October and a trough from December to March.
- Ulcerative colitis births exhibited a less pronounced increase from June to August and a decrease from December to February.
- The observed seasonal pattern for Crohn disease births mirrored findings for childhood type 1 diabetes.
Conclusions:
- A seasonal effect on births is evident for childhood-onset Crohn disease, aligning with type 1 diabetes patterns.
- Summer births are associated with a higher frequency of Crohn disease diagnosis in children.
- The findings suggest potential shared environmental influences on the development of these autoimmune conditions.
Purpose:
In some geographical areas, including Slovakia, children with diabetes mellitus type 1 are born more often in summer than in late autumn and winter. Does this also apply to another autoimmune disorder - inflammatory bowel disease - in Slovakia?
Basic Procedures:
The month of birth was recorded for 30 boys and 36 girls with Crohn disease and 23 boys and 40 girls with ulcerative colitis. The monthly numbers of births were adapted to the length of the given month, divided by the number of boys or girls born in the whole Slovak children population in the same calendar month in comparable years, transformed to moving averages from three successive values each, and expressed as the fraction of the yearly total, which was equal to 1. According to the null hypothesis, there should be equal probability (1/12) of being born in any month. The significance of departures from this value was evaluated with cosinor regression using two sinusoidal functions with period lengths of 12 and 6 months. The most illustrative measure is the relation of the corridor of 95% confidence for the total approximating function to the midline estimating statistic of rhythm (the mesor) (1/12). Significant departures up or down are recognized as nonoverlapping of the mesor straight line by the confidence corridor.
Main Findings:
These were similar to those reported for childhood diabetes mellitus type 1. In our sample of Crohn disease, the number of births was markedly higher between June and October and lower between December and March. In ulcerative colitis, there was a slight increase between June and August and a decrease between December and February.
Principal Conclusions:
The seasonal effect on births of children with later childhood-onset Crohn disease is similar to that described for diabetes mellitus type 1, i.e., maximal frequency of births in summer.
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