Table 2 Final multivariable logistic regression of young mother’s HIV infection using the development and validation data sets for Model One from the 2010, 2011–2012, and 2012–2013 prevention of mother-to-child transmission surveys, South Africa

Risk factor

Coefficient

Odds Ratio (95% CI)

P-value

Score (coefficient*10)

Coefficient

Odds Ratio (95% CI)

P-value

Score (coefficient*10)

Age of mother (years)

 < 20

0

1

-

0

0

1

-

0

20–24

0.81

2.26

(1.62–3.14)

 < 0.001

8

0.75

2.11

(1.38–3.23)

0.001

7

Planned pregnancy

No

0.52

1.68

(1.24–2.27)

0.001

5

Yes

0

1

-

0

Knowledge of weeks pregnant when received last HIV test result

No

0

1

-

0

0

1

-

0

Yes

0.83

2.30

(1.39–3.82)

0.001

8

0.68

1.98

(1.01–3.85)

0.046

7

Knowledge of HIV status of child’s father

No

0.82

2.26

(1.74–2.93)

 < 0.001

8

0.71

2.04

(1.40–2.96)

 < 0.001

7

Yes

0

1

-

0

0

1

-

0

Ethnicity

Black

1.61

5.03

(2.32–10.89)

 < 0.001

16

2.56

12.94

(1.79–93.59)

0.011

26

Non-black

0

1

-

0

0

1

-

0

Knowledge of breastfeeding as a mode of MTCT

No

0.82

2.28

(1.60–3.25)

 < 0.001

8

0.77

2.17

(1.29–3.64)

0.003

8

Yes

0

1

-

0

0

1

-

0

Knowledge of PMTCT programme

No

0

1

-

0

0

1

-

0

Yes

0.67

1.95

(1.32–2.88)

0.001

7

1.00

2.71

(1.39–5.27)

0.003

10

Number of pregnancies

1

0

1

-

0

 >  = 2

0.49

1.64

(1.26–2.12)

 < 0.001

5

Type of house

Brick/cement

-

-

-

-

Informal

0.35

1.42

(1.07–1.89)

0.016

4

Type of toilet

Flush

0.28

1.32

(1.02–1.72)

0.035

3

Pit-latrine/Portable/other

0

1

-

0