Objective An individual’s birth month has a significant impact on the diseases they develop during their lifetime. Previous studies reveal relationships between birth month and several diseases including atherothrombosis, asthma, attention deficit hyperactivity disorder, and myopia, leaving most diseases completely unexplored. This retrospective population study systematically explores the relationship between seasonal affects at birth and lifetime disease risk for 1688 conditions.Methods We developed a hypothesis-free method that minimizes publication and disease selection biases by systematically investigating disease-birth month patterns across all conditions. Our dataset includes 1 749 400 individuals with records at New York-Presbyterian/Columbia University Medical Center born between 1900 and 2000 inclusive. We modeled associations between birth month and 1688 diseases using logistic regression. Significance was tested using a chi-squared test with multiplicity correction.Results We found 55 diseases that were significantly dependent on birth month. Of these 19 were previously reported in the literature (P < .001), 20 were for conditions with close relationships to those reported, and 16 were previously unreported. We found distinct incidence patterns across disease categories.Conclusions Lifetime disease risk is affected by birth month. Seasonally dependent early developmental mechanisms may play a role in increasing lifetime risk of disease.

Background and Purpose Thrombolysis rates among minor stroke (MS) patients are increasing due to increased recognition of disability in this group and guideline changes regarding treatment indications. We examined the association of delays in door-to-needle time (DTN) with stroke severity. Methods We performed a retrospective analysis of all stroke patients who received tissue plasminogen activator in our emergency department between 7/1/2011 and 2/29/2016. Baseline characteristics and DTN were compared between MS (NIHSS ≤5) and non-minor strokes (NIHSS>5). We applied causal inference methodology to estimate the magnitude and mechanisms of the causal effect of stroke severity on DTN. Results Of 315 patients, 133 (42.2%) had NIHSS ≤5. Median DTN was longer in MS than non-minor strokes (58 vs. 53 minutes, P=0.01); fewer MS patients had DTN ≤45 minutes (19.5% vs. 32.4%, P=0.01). MS patients were less likely to use Emergency Medical Services (EMS) (62.6% vs. 89.6%, P<0.01) and to receive EMS pre-notification (43.9% vs. 72.4%, P<0.01). Causal analyses estimated MS increased average DTN by 6 minutes, partly through mode of arrival. EMS pre-notification decreased average DTN by 10 minutes in MS patients. Conclusion MS had longer DTN times, an effect partly explained by patterns of EMS pre-notification. Interventions to improve EMS recognition of MS may accelerate care.