The month of birth and the incidence of multiple sclerosis in the israeli population

Background: Recent studies on date of birth of multiple sclerosis (MS) patients showed a spring peak and an autumn nadir. We examined the effect of date of birth in a large group of MS patients and non-MS patients, compared to the general population in Israel. Methods: A retrospective analysis was performed in a large cohort of MS patients and patients with other neurological disorders. The date of birth, gender, and country of birth were identified for each patient. The results were compared to a national database. Results: There were 2,264 MS patients and 1,758 patients with other diagnoses. No significant peak or nadir in the date of birth was identified in either group, both in patients born in Israel or in immigrants. No difference was found compared to the national birth rate. When we controlled for the country of birth, there was no difference. Conclusion: An increased frequency of MS patients born in the months of April and May was considered as a proof of maternal influence. The results of our study show that this finding is not consistent worldwide. The month of birth was not found to be a significant factor in Israeli MS patients.