Table 2 Comparison of differences between the case group and control group

Patient age (years)

(32.68 ± 4.78)

(33.06 ± 4.24)

0.738

Gestational age (weeks)

6.53 ± 1.24

6.65 ± 1.32

0.637

Crown-rump length (mm)

(7.98 ± 8.43)

(8.65 ± 8.63)

0.597

Number of caesarean sections

1.39 ± 0.53

1.35 ± 0.48

0.692

Number of abortions

1.51 ± 1.31

1.94 ± 1.28

0.105

Mean gestational sac diameter (mm)

(24.99 ± 10.80)

(30.07 ± 11.16)

0.024

RMT (mm)

(3.33 ± 1.52)

(2.01 ± 0.84)

0.000

Percentages of the total number of grade 2 and 3 blood flow

36.7% (18/49)

67.3% (33/49)

0.002

Percentages of cases with normal heartbeat

69.4% (34/49)

57.1% (28/49)

0.209

Percentages of type I CSP

38.8% (19/49)

14.3% (7/49)

0.006

Percentages of type III CSP

10.2% (5/49)

34.7% (17/49)

0.004