Table 1 Characteristics of pregnant women with and without preeclampsia

Maternal age at conception, years, mean ± SD

30.1 ± 3.86

31.2 ± 4.14

< 0.0001

Maternal Pre-pregnancy weight, kg, mean ± SD

52.7 ± 7.63

57.1 ± 10.12

< 0.0001

Maternal height, cm, mean ± SD

159.9 ± 5.01

159.5 ± 5.27

0.237

Pre-pregnancy BMI, kg/m², mean ± SD

20.6 ± 2.73

22.4 ± 3.77

< 0.0001

Smoke during pregnancy, n (%)

175 (0.6)

4 (1.1)

0.221

Parity

 Nulliparous, n (%)

20477 (68.2)

269 (71.5)

0.170

 Parous with previous PIH, n (%)

93 (0.3)

8 (2.2)

< 0.0001

 Pregnancy interval in years, mean ± SD

5.7 ± 3.27

6.9 ± 3.75

0.001

Medical history

 Chronic hypertension, n (%)

119 (0.4)

7 (1.9)

< 0.0001

 Diabetes mellitus, n (%)

111 (0.4)

2 (0.5)

0.608

Family history of chronic hypertension, n (%)

7986 (27.2)

154 (41.7)

< 0.0001

Conception

0.003

 Spontaneous, n (%)

28228 (97.0)

344 (94.3)

 In-vitro fertilization, n (%)

880 (3.0)

21 (5.8)