Table 1. Demographic information and comparison of the frequency of the pregnancy-related variables between two groups, i.e., Natural pregnancy and ART-induced pregnancy.
Variables All cases (n=2857)
Natural pregnancy
[n=2577 (90.2%)]
ART-induced pregnancy
[n=280 (9.8%)]
p Classification of ART cases based on the causes of infertility
Male factor Female factor Other Both
AGE [n(%)]
< 25
25≥ ≤35
> 35
324 (12.57)
1625 (63.06)
628 (24.37)
14 (5)
162 (57.86)
104 (37.14)
<0.001a 7 (2.50)
63 (22.50)
28 (10)
1 (0.36)
30 (10.72)
24 (8.57)
6 (2.14)
60 (21.43)
42 (15)
0
9 (3.21)
10 (3.57)
BMI [n(%)]
< 18
18-24.9
25-29.9
30-40
Missed data:
26
72 (2.80)
1185 (45.98)
771 (29.92)
523 (20.30)
Missed data: 6
6 (2.14)
107 (38.21)
106 (37.86)
55 (19.64)
<0.001 3 (1.07)
36 (12.86)
38 (13.57)
18 (6.43)
1 (0.36)
21 (7.50)
22 (7.86)
10 (3.57)
1 (0.36)
43 (15.36)
39 (13.93)
24 (8.57)
1 (0.36)
7 (2.50)
7 (2.50)
3 (1.07)
Have child with cardiac disease [n(%)]
No
Yes
2382 (92.43)
195 (7.57)
280 (100)
0
<0.001 98 (35)
0
55 (19.64)
0
108 (38.57)
0
19 (6.79)
0
Increased NT [n(%)]
No
Yes
2365 (91.77)
212 (8.23)
272 (97.14)
8 (2.86)
<0.001 96 (34.29)
2 (0.71)
54 (19.29)
1 (0.36)
104 (37.14)
4 (1.42)
18 (6.43)
1 (0.36)
Extra-cardiac anomalies in ultrasound [n(%)]
No
Yes
2022 (78.46)
555 (21.54)
268 (95.71)
12 (4.29)
<0.001 94 (33.57)
4 (1.43)
52 (18.57)
3 (1.07)
103 (36.78)
5 (1.79)
19 (6.79)
0
Type of extra-cardiac anomalies:
No obvious non-cardiac anomalies
CPC 
SUA
Cardiac echogenic focus
Pyelectasis
Echogenic Bowel
CPC + SUA
Cardiac echogenic focus +CPC
Pyelectasis +CPC
Cardiac echogenic focus +SUA
Echogenic Bowel + SUA
Cardiac echogenic focus + Pyelectasis
Cardiac echogenic focus+ Pyelectasis + echogenic bowel
2021 (78.42)
234 (9.08)
58 (2.25)
177 (6.87)
45 (1.75)
6 (0.23)
2 (0.08)
11 (0.43)
14 (0.54)
2 (0.08)
1 (0.04)
5 (0.19)
1 (0.04)
268 (95.71)
3 (1.07)
1 (0.36)
6 (2.14)
1 (0.36)
0
0
0
1 (0.36)
0
0
0
0
<0.001
0.06
<0.01
0.13
...
...
...
...
...
...
...
....
...
94 (33.57)
0
1 (0.36)
1 (0.36)
1 (0.36)
0
0
0
1 (0.36)
0
0
0
0
52 (18.57)
0
0
3 (1.07)
0
0
0
0
0
0
0
0
0
103 (36.79)
3 (1.07)
0
2 (0.71)
0
0
0
0
0
0
0
0
0
19 (6.78)
0
0
0
0
0
0
0
0
0
0
0
0
Mother’s diabetes
No
Yes
2272 (88.16)
305 (11.84)
253 (90.36)
27 (9.64)
0.32 88 (31.43)
10 (3.57)
48 (17.14)
7 (2.50)
98 (35)
10 (3.57)
19 (6.79)
0
Mother’s rheumatic diseases
No
Yes
2540 (98.56)
37 (1.44)
279 (99.64)
1 (0.36)
0.22 97 (34.64)
1 (0.36)
55 (19.64)
0
108 (38.57)
0
19 (6.79)
0
Major cardiac anomaly
No
Yes
Mild cardiac anomaly
1432 (55.57)
34 (1.32)
1111 (43.11)
136 (48.57)
0
144 (51.43)
0.08
0.009
57 (20.36)
0
41 (14.64)
23 (8.21)
0
32 (11.43)
48 (17.14)
0
60 (21.43)
8 (2.86)
0
11 (3.93)
Fetal Non-major Cardiac Anomalies
no
VSD
ASD
Arrhythmia
VSD + ASD
VSD + Arrhythmia
VSD + ASD
1503 (58.32)
1045 (40.55)
3 (0.12)
20 (0.78)
1 (0.04)
5 (0.19)
0
137 (48.93)
140 (50)
0
0
0
2 (0.71)
1 (0.36)
0.003
0.67
0.27
0.17
0.30
0.17
57 (20.35)
40 (14.29)
0
0
0
1 (0.39)
0
24 (8.57)
31 (11.07)
0
0
0
0
0
48 (17.14)
58 (20.71)
0
0
0
1 (0.36)
1 (0.36)
8 (2.86)
11 (3.93)
0
0
0
0
0
Fetal echocardiographs
Medical indication by parents
1987 (77.10)
590 (22.90)
195 (69.64)
85 (30.36)
0.006 63 (22.50)
35 (12.50)
41 (14.64)
14 (5)
76 (27.14)
32 (11.43)
15 (5.36)
4 (1.43)

a: Comparison of pregnancy frequency in different age ranges
ART= Assisted reproductive technology.
BMI= Body mass index
NT= Nuchal thickness
CPC= Choroid plexus cysts
SUA= Single umbilical cord artery
VSD: Ventricular septal defect
ASD: Atrial septal defect