Table 2 Percentage of adverse birth outcomes by prenatal exposure factors in the MACE Study (2013–2017)

Median annual exposure to air pollution (μg/m³)

 PM2.5

13.2

13.2

13.2

 SO₂

2.6

2.2

2.7

 NOx

32.6

29.2

34.6

Behavioural factors

 Maternal smoking (Smoker)

8.6

6.9

11.5

 Passive smoking (PSmoker)

29.0

27.8

34.5

 Alcohol consumption

9.7

9.7

8.0

Low socio-economic factors

 Primary or less maternal education (PLEduc)

3.2

2.8

5.3

 Maternal Unemployment (Unemp)

18.3

20.8

21.2

 Low maternal annual income (LInc) (< US$2000)

91.4

91.7

89.4

 Low socio-economic housing (LSEH)

40.9

34.7

33.6

Demographic factors

 Maternal age in years Mean (SD)

25.7(6.5)

25.5(6.2)

25.9(5.7)

 Multiparous

16.1

23.9

15.3

 Child gender (Female)

45.2

44.4

50.4

Clinical factors

 HIV status (Positive)

34.4

34.7

36.3

 Syphilis (Positive)

9.7

9.7

4.4

 BMI at first trimester (BMIT1) (kg/m²)

25.5(6.6)

25.0(5.5)

25.8(6.3)

 Gestational weight gain (WeightGain) (kg)

6.3(6.1)

6.6(6.1)

6.5 (6.0)

 Physical exercise (at least once in a week)

45.2

44.4

44.2

 Residential location (South Durban)

52.7

45.8

55.8