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Table 1 Comparison of demographic and clinical characteristics of participants across maternal age groups

From: Adverse maternal and neonatal outcomes among singleton pregnancies in women of very advanced maternal age: a retrospective cohort study

 

20–34 years

35–42 years

≥ 43 years

Overall

P

n

%

n

%

n

%

n

N

298,844

77.4

83,913

21.7

3266

0.8

386,023

 

Maternal age, year (mean ± SD)

28.7 ± 3.7

 

37.2 ± 2.0

 

44.2 ± 1.9

  

< 0.001

Gravidity (median, IQR)

2 (2)

 

2 (2)

 

3 (3)

  

< 0.001

Parity (Median, IQR)

1 (1)

 

1 (2)

 

1 (2)

  

< 0.001

 0

137,021

45.9

22,231

26.5

910

27.9

160,162

< 0.001

 1

103,802

34.7

32,606

38.9

958

29.3

137,366

 

 ≥2

53,739

18.0

27,619

32.9

1342

41.1

82,700

 

 Missing

4282

1.4

1457

1.7

56

1.7

5795

 

Neighbourhood income quintile

 1st (Lowest)

69,635

23.3

16,583

19.8

753

23.1

86,971

< 0.001

 2nd

55,635

18.6

13,656

16.3

523

16.0

69,814

 

 3rd

53,391

17.9

13,787

16.4

536

16.4

67,714

 

 4th

54,983

18.4

16,644

19.8

576

17.6

72,203

 

 5th (Highest)

52,827

17.7

20,171

24.0

758

23.2

73,756

 

 Missing

12,373

4.1

3072

3.7

120

3.7

15,565

 

Neighbourhood education quintile a

 1st (Lowest)

56,392

18.9

9173

10.9

381

11.7

65,946

< 0.001

 2nd

62,349

20.9

13,141

15.7

510

15.6

76,000

 

 3rd

61,921

20.7

16,257

19.4

574

17.6

78,752

 4th

61,929

20.7

21,041

25.1

767

23.5

83,737

 5th (Highest)

46,246

15.5

21,776

26.0

935

28.6

68,957

 Missing

10,007

3.3

2525

3.0

99

3.0

12,631

BMI (kg/m2) (mean ± SD)

25.3 ± 6.2

 

25.9 ± 6.1

 

26.4 ± 6.2

  

< 0.001

 Underweight (<18.5)

15,876

5.3

2634

3.1

64

2.0

18,574

< 0.001

 Normal weight (18.5–24.9)

134,814

45.1

35,362

42.1

1235

37.8

171,411

 

 Overweight (25–29.9)

62,058

20.8

19,415

23.1

780

23.9

82,253

 

 Obese (≥ 30)

46,129

15.4

14,087

16.8

580

17.8

60,796

 

 Missing

39,967

13.4

12,415

14.8

607

18.6

52,989

 

ART type

 IVF/ IVF + ICSI

2530

0.8

2890

3.4

575

17.6

5995

< 0.001

 IUI

3561

1.2

2026

2.4

82

2.5

5669

 Other

87

0.0

72

0.1

< 6

S

160

 None

292,666

97.9

78,925

94.1

2608

79.9

374,199

Previous cesarean section (yes)

35,687

11.9

18,038

21.5

732

22.4

54,457

< 0.001

Maternal health problems (yes)

30,889

10.3

11,607

13.8

562

17.2

43,058

< 0.001

 Pre-existing hypertension

2025

0.7

1369

1.6

117

3.6

3511

< 0.001

 Pre-gestational diabetes mellitus

2427

0.8

1216

1.4

76

2.3

3719

< 0.001

 Maternal heart disease

3407

1.1

1125

1.3

46

1.4

4578

< 0.001

 Maternal pulmonary diseases

12,188

4.1

3038

3.6

127

3.9

15,353

< 0.001

 Maternal endocrine disorders

12,569

4.2

5712

6.8

268

8.2

18,549

< 0.001

 Thrombophilia

198

0.1

69

0.1

7

0.2

274

0.003

Drug/alcohol/tobacco use (yes)

38,228

12.8

5897

7.0

209

6.4

44,334

< 0.001

 Drug use (any drug)

6051

2.0

680

0.8

21

0.6

6752

< 0.001

 Alcohol use b

5489

1.8

1499

1.8

65

2.0

7053

0.26

 Maternal smoking c

32,974

11.0

4427

5.3

157

4.8

37,558

< 0.001

Infant gender

 Male

153,326

51.3

42,894

51.1

1643

50.3

197,863

0.62

 Female

145,323

48.6

40,968

48.8

1622

49.7

187,913

 Undetermined or missing

195

0.1

51

0.1

< 6

S

247

  1. ART assisted reproductive technology, BMI body mass index, ICSI intracytoplasmic sperm injection, IQR interquartile range, IUI intra-uterine insemination, IVF in vitro fertilization, S suppression due to cell < 6, SD standard deviation
  2. aPercentage of university degrees among population between 25 and 64 years old at dissemination areas level
  3. bAlcoholic drink during pregnancy
  4. cSmoking at any time during pregnancy
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