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Table 1 Baseline characteristics of the eligible study sample and propensity score matched sample

From: Is in vitro fertilization associated with preeclampsia? A propensity score matched study

  

Eligible study sample (n = 3084)

Propensity score matched sample (n = 948)

  

IVF group (n = 474)

Non-IVF group (n = 2610)

P value

IVF group (n = 474)

Non-IVF group (n = 474)

P value

Maternal demographics

       

Age

Year, mean (SD)

38.3 (3.3)

34.8 (4.2)

<0.001

38.3 (3.3)

38.4 (3.3)

0.97

Age at marriage

Year, mean (SD)

30.8 (4.1)

29.3 (3.8)

<0.001

30.8 (4.1)

31.0 (4.1)

0.91

Parity

0, n (%)

370 (78.1)

1319 (50.5)

<0.001

370 (78.1)

378 (79.8)

0.74

 

≥1, n (%)

104 (21.9)

1291 (49.5)

 

104 (21.9)

96 (20.3)

 

Abortion

0, n (%)

291 (61.4)

1767 (67.7)

0.009

291 (61.4)

304 (64.1)

0.39

 

1-2, n (%)

152 (32.1)

734 (28.1)

 

152 (32.1)

136 (28.7)

 
 

3≤, n (%)

31 (6.5)

109 (4.2)

 

31 (6.5)

34 (7.2)

 

Work

Homemaker, n (%)

189 (39.9)

1122 (43.0)

0.31

189 (39.9)

190 (40.1)

0.93

 

Full time, n (%)

248 (52.3)

1268 (48.6)

 

248 (52.3)

238 (50.2)

 
 

Part time, n (%)

36 (7.6)

200 (7.7)

 

36 (7.6)

45 (9.5)

 
 

Missing, n (%)

1 (0.2)

20 (0.8)

 

1 (0.2)

1 (0.2)

 

Maternal health status

       

Height

cm, mean (SD)

160.0 (5.4)

159.4 (5.2)

0.015

160.0 (5.4)

159.8 (5.1)

0.75

Weight before pregnancy

kg, mean (SD)

52.4 (6.9)

51.5 (7.8)

0.011

52.4 (6.9)

52.0 (7.2)

0.74

Smoking during pregnancy

Yes, n (%)

6 (1.3)

92 (3.5)

0.01

6 (1.3)

6 (1.3)

0.27

Drinking during pregnancy

Yes, n (%)

0 (0)

11 (0.4)

0.39

0 (0)

0 (0)

NA

Family history of hypertension

Yes, n (%)

110 (23.2)

414 (15.9)

<0.001

110 (23.2)

104 (21.9)

0.82

Systolic blood pressure <20 weeks of gestation

mmHg, mean (SD)

110.4 (10.4)

108.4 (10.2)

<0.001

110.4 (10.4)

110.9 (9.9)

0.75

Diastolic blood pressure <20 weeks of gestation

mmHg, mean (SD)

64.8 (7.3)

62.8 (7.1)

<0.001

64.8 (7.3)

65.0 (7.0)

0.86

Maternal medical complication

       

Central nervous system disease

Yes, n (%)

0 (0)

27 (1.0)

0.016

0 (0)

1 (0.2)

>0.99

Cerebrovascular disease

Yes, n (%)

0 (0)

4 (0.2)

>0.99

0 (0)

1 (0.2)

>0.99

Asthma

Yes, n (%)

13 (2.7)

92 (3.5)

0.49

13 (2.7)

9 (1.9)

0.29

Respiratory disease (except asthma)

Yes, n (%)

2 (0.4)

3 (0.1)

0.17

2 (0.4)

4 (0.8)

>0.99

Gastrointestinal disease

Yes, n (%)

2 (0.4)

33 (1.3)

0.15

2 (0.4)

1 (0.2)

0.57

Liver disease

Yes, n (%)

3 (0.6)

16 (0.6)

>0.99

3 (0.6)

2 (0.4)

0.57

Hematologic disease

Yes, n (%)

2 (0.4)

16 (0.6)

>0.99

2 (0.4)

2 (0.4)

>0.99

Cardiovascular disease

Yes, n (%)

5 (1.1)

51 (2.0)

0.26

5 (1.1)

4 (0.8)

0.42

Hyperthyroidism

Yes, n (%)

7 (1.5)

47 (1.8)

0.85

7 (1.5)

4 (0.8)

>0.99

Hypothyroidism

Yes, n (%)

13 (2.7)

70 (2.7)

0.88

13 (2.7)

14 (3.0)

0.29

Psychiatric disease

Yes, n (%)

10 (2.1)

64 (2.5)

0.75

10 (2.1)

9 (1.9)

>0.99

Autoimmune disease

Yes, n (%)

9 (1.9)

55 (2.1)

0.86

9 (1.9)

6 (1.3)

>0.99

Pre-existing diabetes mellitus

Yes, n (%)

1 (0.2)

15 (0.6)

0.49

1 (0.2)

2 (0.4)

0.57

Paternal demographics

       

Age

Year, mean (SD)

40.8 (4.8)

37.3 (4.9)

<0.001

40.8 (4.8)

40.6 (4.8)

0.25

Age at marriage

Year, mean (SD)

33.3 (5.3)

31.7 (4.8)

<0.001

33.3 (5.3)

33.2 (5.6)

0.37

Paternal health status

       

Partner's smoking status

Yes, n (%)

136 (28.7)

705 (27.0)

0.31

136 (28.7)

140 (29.5)

0.84

 

Missing, n (%)

6 (1.3)

59 (2.3)

 

6 (1.3)

6 (1.3)

 

Partner's height

cm, mean (SD)

172.7 (5.8)

173.1 (5.7)

0.16

172.7 (5.8)

173.4 (5.6)

0.10

Partner's weight

kg, mean (SD)

69.6 (9.2)

69.8 (9.6)

0.70

69.6 (9.2)

70.1 (9.0)

0.64

  1. IVF, in vitro fertilization; SD, standard deviation.
  2. Chi-squared or Fisher’s exact tests for categorical variables and t-tests for continuous variables were used for the whole study population. Conditional logistic regression for categorical variables and regression analysis using the fixed effect model for continuous variables were used in the propensity score matched sample.
  3. Values in bold are significant at the p = 0.05 level.