Table 1 Maternal and neonatal characteristics of the participants

Maternal age [n (%)]

 ≤ 30 years

11 (35.48)

76 (55.47)

0.044

22 (27.85)

250 (40.78)

0.027

 > 30 years

20 (64.52)

61 (44.53)

57 (72.15)

363 (59.22)

Gravidity [n (%)]

 ≤ 1

17 (54.84)

60 (43.80)

0.265

48 (60.76)

336 (54.81)

0.317

 ≥ 2

14 (45.16)

77 (56.20)

31 (39.24)

277 (45.19)

Parity [n(%)]

 0

24 (77.42)

91 (66.42)

0.234

67 (84.81)

511 (83.36)

0.744

 ≥ 1

7 (22.58)

46 (33.58)

12 (15.19)

102 (16.64)

Gestational weight gain (kg)

13.0 (11.0–16.0)

16.0 (12.5–20.0)

0.037

15.0 (12.0–18.0)

15.0 (12.0–18.0)

0.923

Pre-pregnancy BMI (kg/m²)

21.00 (20.00–23.73)

20.56 (18.95–22.00)

0.083

21.23 (19.53–22.86)

20.83 (19.23–23.16)

0.811

Gestational age at delivery (weeks)

33 (31–35)

35 (34–36)

< 0.001

36 (34–37)

36 (35–37)

0.689

ART [n(%)]

5 (16.13)

15 (10.95)

0.538

58 (73.42)

433 (70.64)

0.608

Pre-gestation systolic pressure (mmHg)

115.0 (107.0–120.0)

111.0 (106.5–120.0)

0.799

113.0 (110.0–120.0)

111.0 (108.0–120.0)

0.528

Pre-gestation diastolic pressure (mmHg)

70.0 (65.0–76.0)

70.0 (65.0–77.0)

0.821

70.0 (63.0–73.0)

70.0 (65.0–75.0)

0.362

Delivery

 Vaginal delivery [n(%)]

2 (6.45)

15 (10.95)

0.742

0 (0.00)

49 (7.99)

0.009

 Cesarean section [n(%)]

29 (93.55)

122 (89.05)

79 (100.00)

564 (92.01)

Obstetric complications

 GDM [n(%)]

3 (9.68)

27 (19.71)

0.188

20 (25.32)

129 (21.04)

0.385

 ICP [n(%)]

3 (9.68)

9 (6.57)

0.465

10 (12.66)

61 (9.95)

0.455

 Preeclampsia [n(%)]

8 (25.81)

23 (16.79)

0.242

19 (24.05)

111 (18.11)

0.203

 Hypothyroidism [n(%)]

1 (3.23)

13 (9.49)

0.471

10 (12.66)

62 (10.11)

0.486

 Premature rupture of membranes [n(%)]

1 (3.23)

10 (7.30)

0.691

9 (11.39)

80 (13.05)

0.679

 Anemia along with pregnancy [n(%)]

8 (25.81)

41 (29.93)

0.649

22 (27.85)

148 (24.14)

0.472

Newborn characteristics

 Birth weight of the larger fetus (g)

1980.97 ± 475.02

2295.36 ± 405.29

< 0.001

2553.29 ± 508.76

2524.59 ± 359.61

0.628

 Birth weight of the smaller fetus (g)

1422.90 ± 434.94

2110.29 ± 402.21

< 0.001

1878.61 ± 445.93

2309.76 ± 337.48

< 0.001

 1-min Apgar (average score of two fetuses)

8.71 ± 1.24

9.41 ± 0.82

< 0.001

9.39 ± 0.76

9.49 ± 0.75

0.287

 5-min Apgar(average score of two fetuses)

9.67 ± 0.69

9.90 ± 0.31

0.006

9.79 ± 0.64

9.91 ± 0.33

0.013

Neonatal anemia [n(%)]

6 (19.35)

21 (15.33)

0.592

8 (10.13)

59 (9.62)

0.887

 NRDS [n(%)]

18 (58.06)

18 (13.14)

< 0.001

14 (17.72)

40 (6.53)

< 0.001