Table 2.
Estimated percent of preterm births attributed to risk factors for all 81 LMICs, in the final and extended models
| Final model PAF (Min-Max) | Extended model PAF (Min-Max) | |
|---|---|---|
|
Pregnancy history
|
|
|
| Short birth interval |
1.96 (0.70-4.06) |
1.81 (0.63-3.70) |
| Young maternal age (<18 years) & primiparity |
1.24 (0.23-3.65) |
1.13 (0.22-3.30) |
| Maternal age 18-35 years & parity >3 |
3.32 (1.39-5.12) |
3.06 (1.26-4.98) |
| Older maternal age (>35 years) & parity >3 |
2.15 (0.72-3.66) |
1.98 (0.67-3.44) |
|
Maternal nutritional status:
| ||
| Low zinc intake |
N/A |
2.01 (0.90-2.51) |
| Maternal anemia |
13.07 (5.99-17.20) |
12.05 (5.46-15.52) |
| Low calcium intake |
N/A |
6.96 (0.07-10.88) |
| Short height (<145 cm) |
1.50 (0.05-5.89) |
1.39 (0.04-5.50) |
| Low BMI (<18.5 kg/m2) |
2.96 (0.52-4.49) |
2.73 (0.48-4.16) |
|
Maternal morbidity
|
|
|
| Chronic hypertension |
4.86 (3.43-7.32) |
4.47 (3.21-7.02) |
|
Fetal characteristics:
| ||
| Twin pregnancy |
2.19 (1.66-5.18) |
2.02 (1.51-4.95) |
| Fetal gender (male) |
1.72 (1.54-2.05) |
1.59 (1.41-1.96) |
|
Environmental exposures during pregnancy:
| ||
| Indoor air pollution |
9.72 (0.17-14.32) |
8.94 (0.16-13.01) |
| Ambient air pollution |
3.17 (0.73-4.51) |
2.93 (0.66-4.09) |
| Intimate partner violence |
2.95 (1.83-4.64) |
2.73 (1.65-4.40) |
| Tobacco smoking |
0.16 (0.01-1.48) |
0.15 (0.01-1.42) |
|
Uterine, placental, and cervical factors
|
|
|
| Short cervical length (<25mm) |
2.22 (1.98-2.63) |
2.04 (1.81-2.52) |
|
Pregnancy-related morbidity:
| ||
| Gestational diabetes |
2.53 (1.63-3.50) |
2.33 (1.51-3.27) |
| Pre-eclampsia |
0.72 (0.28-1.14) |
0.66 (0.27-1.04) |
|
Maternal infections:
| ||
| HIV |
0.42 (0.00-6.85) |
0.38 (0.00-6.19) |
| Malaria |
1.92 (0.00-9.91) |
1.75 (0.00-9.05) |
| Syphilis |
1.03 (0.24-2.34) |
0.95 (0.22-2.12) |
| Chlamydia |
0.47 (0.27-1.32) |
0.43 (0.25-1.25) |
| Asymptomatic bacteriuria |
0.07 (0.04-0.20) |
0.06 (0.04-0.20) |
| Periodontal Infection |
3.13 (0.32-5.68) |
2.90 (0.29-5.32) |
| Bacterial vaginosis |
9.53 (8.03-11.70) |
8.77 (7.29-11.23) |
| Group B Strep colonization |
N/A |
1.84 (1.21-2.82) |
| Total | 73.0% | 78.1% |
BMI – body mass index, HIV – human immunodeficiency virus, PAF – population attributable fraction