Table 1. Evaluation of seasonality of birth by histology, gender and age.

Histology		Walter and Elwood's test
ICCC-2	Cases	χ 2	P-value	Theta (θ)	Peak-month
Ependymoma	162	8.0	0.02	13.81	January
Astrocytoma	607	1.45	0.48
PNET	270	0.61	0.74
Other glioma	76	3.28	0.19
Other specified intracranial and intraspinal neoplasm	199	1.63	0.44
Unspecified intracranial and intraspinal neoplasm	326	0.85	0.65
All CNS tumours	1640	0.37	0.83
Ependymoma by age and gender
0–4 years	69	2.2	0.34
5–19 years	93	10.3	0.006	−4.30	December
Boys	88	4.0	0.13
Girls	74	9.7	0.008	−13.78	December

CNS=central nervous system; ICCC-2=International Childhood Cancer Classification second edition; PNET=primitive neuroectodermal tumour.