Table 6. The clinical pregnancy rate according to the operation times.

	First cycle	Second cycle	Third cycle	≥ Fourth cycle	χ2 value	P value
Pregnant group	42	26	17	4	4.655	0.199
Non-pregnant group	256	154	54	27
Clinical pregnancy rate (%)	14.09%	14.44%	23.94%	12.9%

	One cycle	Two cycles	Three cycles	≥ four cycles
Pregnant couples	42	68	85	89
Infertile couples	298	222	139	116
Accumulative pregnancy rate (%)	14.09%	30.63%	61.15%	76.72%