Table 5 Hazard ratios of under-five mortality by previous birth interval according to mother’s age at first birth in India

Less than and equal 18 years

19 to 24 years

25 to 29 years

30 years and above

HR^a

95% CI

HR^a

95% CI

HR^a

95% CI

HR^a

95% CI

HR^a

95% CI

Previous Birth Interval

First-order birth

2.72

**

1.69

4.37

2.34

**

1.84

2.96

2.49

**

1.35

4.60

2.86

*

1.04

7.86

Less than 12 months

4.36

**

3.54

5.36

3.32

**

2.85

3.88

2.45

**

1.59

3.78

2.16

0.78

6.01

12 to 23 months

1.74

**

1.51

2.01

1.76

**

1.59

1.95

1.81

**

1.39

2.35

1.87

*

1.03

3.38

24 to 35 months

1.15

0.99

1.32

1.12

*

1.01

1.25

1.21

0.92

1.58

1.43

0.78

2.62

36 to 47 months ®

48 to 59 months

0.90

0.73

1.11

1.04

0.90

1.21

1.29

0.91

1.81

0.75

0.29

1.94

60 to 85 months

1.08

0.88

1.33

1.17

*

1.01

1.36

1.49

*

1.06

2.09

1.97

0.94

4.16

86 months and above

1.91

**

1.56

2.34

1.59

**

1.33

1.89

2.20

**

1.50

3.22

1.39

0.50

3.88