Table 3.
Estimated percent of preterm births attributed to risk factors for Sub-Saharan region and South Asia region*, in the final and extended models
| Sub Saharan Africa |
South Asia |
|||
|---|---|---|---|---|
|
|
Final model PAF (Min-Max)
|
Extended model PAF (Min-Max)
|
Final model PAF (Min-Max)
|
Extended model PAF (Min-Max)
|
|
Pregnancy history:
| ||||
| Short birth interval |
1.54 (0.70-4.06) |
1.40 (0.63-3.70) |
2.41 (1.32-3.60) |
2.26 (1.19-3.48) |
| Young maternal age (<18 years) & primiparity |
1.50 (0.48-2.60) |
1.37 (0.44-2.35) |
1.03 (0.59-3.65) |
0.95 (0.57-3.30) |
| Maternal age 18-35 years & parity >3 |
3.90 (1.42-4.85) |
3.56 (1.32-4.40) |
2.90 (1.45-4.35) |
2.72 (1.32-4.21) |
| Older maternal age (>35 years) & parity >3 |
2.88 (1.22-3.56) |
2.63 (1.13-3.26) |
1.01 (0.72-2.26) |
0.95 (0.67-2.19) |
|
Maternal nutritional status:
| ||||
| Low zinc intake |
0.00 (0.00-0.00) |
1.88 (1.78-2.14) |
0.00 (0.00-0.00) |
2.19 (1.44-2.46) |
| Maternal anemia |
12.40 (5.99-16.17) |
11.30 (5.46-14.58) |
14.87 (13.24-15.16) |
13.88 (12.26-14.08) |
| Low calcium intake |
0.00 (0.00-0.00) |
7.72 (1.01-9.87) |
0.00 (0.00-0.00) |
5.56 (0.93-9.54) |
| Short height (<145 cm) |
0.52 (0.05-1.69) |
0.47 (0.04-1.52) |
2.41 (1.15-2.95) |
2.23 (1.12-2.67) |
| Low BMI (<18.5 kg/m2) |
2.11 (1.02-3.59) |
1.92 (0.92-3.27) |
4.20 (2.50-4.49) |
3.91 (2.28-4.16) |
|
Maternal morbidity:
| ||||
| Chronic hypertension |
6.27 (5.93-7.12) |
5.71 (5.41-6.50) |
3.74 (3.43-4.03) |
3.49 (3.32-3.67) |
|
Fetal Characteristics
|
|
|
|
|
| Twin pregnancy |
2.55 (2.41-2.89) |
2.32 (2.20-2.64) |
1.81 (1.66-2.28) |
1.69 (1.51-2.20) |
| Fetal gender (male) |
1.63 (1.54-1.85) |
1.48 (1.41-1.69) |
1.75 (1.71-1.85) |
1.63 (1.55-1.68) |
|
Environmental exposures during pregnancy:
| ||||
| Indoor air pollution |
11.30 (2.73-13.15) |
10.29 (2.48-11.90) |
9.17 (6.63-11.17) |
8.56 (6.04-10.12) |
| Ambient air pollution |
2.60 (0.88-4.18) |
2.37 (0.79-4.01) |
4.05 (3.85-4.51) |
3.78 (3.51-4.09) |
| Intimate partner violence |
3.09 (2.92-3.51) |
2.82 (2.67-3.20) |
2.73 (2.39-3.97) |
2.56 (2.17-3.84) |
| Tobacco smoking |
0.09 (0.01-0.67) |
0.08 (0.01-0.61) |
0.08 (0.02-0.88) |
0.08 (0.01-0.82) |
|
Uterine, placental, and cervical factors:
| ||||
| Short cervical length (<25mm) |
2.10 (1.98-2.38) |
1.91 (1.81-2.17) |
2.25 (2.20-2.38) |
2.10 (1.99-2.17) |
|
Pregnancy-related morbidity
|
|
|
|
|
| Gestational diabetes |
2.02 (1.91-2.29) |
1.84 (1.74-2.09) |
2.86 (2.75-3.06) |
2.67 (2.49-2.96) |
| Pre-eclampsia |
0.88 (0.83-1.00) |
0.80 (0.76-0.91) |
0.58 (0.28-0.68) |
0.53 (0.28-0.62) |
|
Maternal infections:
| ||||
| HIV |
0.97 (0.03-6.85) |
0.88 (0.03-6.19) |
0.02 (0.00-0.03) |
0.02 (0.00-0.03) |
| Malaria |
4.46 (0.00-9.91) |
4.06 (0.00-9.05) |
0.08 (0.00-0.11) |
0.08 (0.00-0.10) |
| Syphilis |
1.78 (1.54-2.34) |
1.62 (1.40-2.12) |
0.50 (0.35-0.63) |
0.46 (0.32-0.61) |
| Chlamydia |
0.53 (0.50-0.61) |
0.49 (0.46-0.55) |
0.33 (0.27-0.54) |
0.31 (0.25-0.52) |
| Asymptomatic bacteriuria |
0.05 (0.04-0.08) |
0.05 (0.04-0.08) |
0.08 (0.06-0.08) |
0.07 (0.06-0.08) |
| Periodontal infection |
1.88 (0.32-4.65) |
1.71 (0.29-4.26) |
4.47 (2.69-4.91) |
4.17 (2.50-4.55) |
| Bacterial vaginosis |
10.02 (9.48-11.39) |
9.13 (8.65-10.39) |
9.12 (8.24-9.86) |
8.51 (7.98-8.98) |
| Group B Strep colonization |
0.00 (0.00-0.00) |
2.29 (2.17-2.60) |
0.00 (0.00-0.00) |
1.39 (1.21-1.95) |
| Total | 77.1% | 82.1% | 72.4% | 76.8% |
BMI – body mass index, HIV – human immunodeficiency virus, PAF – population attributable fraction
*Bangladesh, Bhutan, India, Nepal, Pakistan.