Table 2 Odds ratios (95% confidence interval) of occurrence of Down syndrome California, 1996–97

Sex of infants

Boy

1

1

Girl

0.85

0.72

1.00

0.84

0.71

0.99

Education of mother

Primary

1.99

1.52

2.62

2.80

2.12

3.72

Vocational

0.97

0.72

1.31

2.24

1.62

3.10

Secondary

1.16

0.90

1.50

1.87

1.44

2.44

University

1

1

P for trend

<0.001

<0.001

Maternal age

-19

1

1

20–22

1.32

0.84

2.08

1.66

0.95

2.92

23–25

1.45

0.94

2.26

2.05

1.14

3.68

26–28

1.40

0.90

2.17

2.18

1.20

3.99

29–31

1.71

1.12

2.63

2.74

1.49

5.04

32–34

3.29

2.20

4.92

5.47

3.00

9.98

35–37

3.72

2.45

5.66

6.27

3.37

11.64

38–40

8.21

5.43

12.40

12.34

6.61

23.05

41–43

20.07

13.12

30.71

28.42

14.98

53.91

44+

19.40

10.30

36.55

27.57

12.22

62.21

Paternal age

-19

1

1

20–22

1.11

0.59

2.10

0.85

0.44

1.67

23–25

1.13

0.61

2.06

0.69

0.35

1.37

26–28

1.27

0.71

2.29

0.65

0.32

1.31

29–31

1.92

1.09

3.38

0.83

0.41

1.66

32–34

1.94

1.10

3.43

0.67

0.33

1.37

35–37

2.55

1.44

4.51

0.68

0.33

1.40

38–40

2.47

1.36

4.49

0.54

0.26

1.13

41–43

6.33

3.55

11.27

1.02

0.49

2.11

44+

6.37

3.58

11.34

0.86

0.41

1.79