Table 1

Temporal patterns and frequency of outcomes and explanatory variables over four consecutive time intervals, each of 63 months

Variable	Time period/observed frequency				Expected frequency	χ²	P value
Variable	1	2	3	4	Expected frequency	χ²	P value
Number of cases	52	57	66	50	56	2.7	0.4
Antenatally diagnosed	29	38	46	35	37	4	0.3
Terminations	2	4	15	5	6	15.5	<0.0001
Live birth	52	55	53	48	52	0.5	0.9
Surgical repair	37	42	41	39	40	0.4	0.9
Alive	30	40	35	29	34	2	0.5
HFOV	15	19	26	19	22	3	0.4
iNO	21	19	29	29	22	3	0.4
Prostin	2	15	23	18	14	16	0.001
ECMO	1	0	5	5	5	4	0.2
Significant cardiac anomaly	10	12	14	14	13	1.1	0.7
Isolated non-cardiac anomaly	4	5	4	2	4	1.5	0.6

ECMO, extracorporeal membrane oxygenation; HFOV, high-frequency oscillatory ventilation; iNO, inhaled nitric oxide.