Table 2

Month of birth for the general population and Crohn's disease (CD) by decade (1941–50; 1951–60; 1961–70)

	Jan	Feb	Mar	Apr	May	June	July	Aug	Sep	Oct	Nov	Dec	Total
Births 41–50	121 568	113 544	127 964	123 961	129 254	122 631	123 359	119 583	119 780	117 480	112 275	118 803
CD births 41–50	26	20	31	27	16	24	26	25	20	23	21	19	278
Exp CD births 41–50	23.30	21.77	24.53	23.76	24.78	23.51	23.65	22.92	22.96	22.52	21.52	22.77

Births 51–60	118 827	113 138	128 071	122 211	126 777	118 837	119 705	115 822	115 968	114 244	107 377	114 030
CD births 51–60	34	35	35	36	49	31	29	33	27	32	21	28	390
Exp CD births 51–60	32.75	31.18	35.30	33.68	34.94	32.75	32.99	31.92	31.96	31.49	29.59	31.43

Births 61–70	140 152	132 757	152 520	141 979	146 563	139 200	141 715	138 147	136 317	134 945	127 271	133 645
CD births 61–70	30	25	31	28	24	26	28	19	27	23	18	21	300
Exp births CD 61–70	25.25	23.92	27.48	25.58	26.40	25.08	25.53	24.89	24.56	24.31	22.93	24.08

Total CD births	90	80	97	91	89	81	83	77	74	78	60	68	968
Total Exp births	81.30	76.87	87.31	83.03	86.12	81.34	82.17	79.73	79.48	78.32	74.05	78.28
Obs/Exp	1.11	1.04	1.11	1.10	1.03	1.00	1.01	0.97	0.93	1.00	0.81	0.87