The worldwide incidence of preterm birth: a systematic review of maternal mortality and morbidity
Stacy Beck, Daniel Wojdyla, Lale Say, Ana Pilar Betran, Mario Merialdi, Jennifer Harris Requejo, Craig Rubens, Ramkumar Menon & Paul FA Van Look
Volume 88, Number 1, January 2010, 31-38
Table 2. Characteristics of the estimates and reports used in a systematic review to estimate the worldwide incidence of preterm birth, by region/country grouping
| Variable | Africa | Asia | Latin America and Caribbean | Developed countriesa | Total |
|---|---|---|---|---|---|
| Total | 22 | 22 | 13 | 35 | 92 |
| Study design | |||||
| Cross-sectional | 10 | 13 | 4 | 29 | 56 |
| Cohort/controlled trial | 3 | 5 | 2 | 1 | 11 |
| Survey | 9 | 4 | 7 | 5 | 25 |
| Type of estimate | |||||
| Population-based: national | 0 | 6 | 3 | 23 | 32 |
| Population-based: subnational | 1 | 5 | 2 | 5 | 13 |
| Facility-based | 21 | 11 | 8 | 7 | 47 |
| Estimate based on | |||||
| Adolescents | 1 | 1 | 0 | 0 | 2 |
| Mixed ethnic group | 0 | 1 | 0 | 0 | 1 |
| Tribal group | 0 | 2 | 0 | 0 | 2 |
| Lower socioeconomic class | 1 | 1 | 2 | 1 | 5 |
| Not specific (general population) | 18 | 15 | 11 | 29 | 73 |
| Unspecified | 2 | 2 | 0 | 5 | 9 |
| Preterm birth definition | |||||
| Less than 37 weeks gestation | 17 | 16 | 11 | 31 | 75 |
| Other | 1 | 1 | 1 | 0 | 3 |
| No definition reported | 4 | 5 | 1 | 4 | 14 |
| Diagnostic procedure | |||||
| Ultrasound | 2 | 1 | 0 | 2 | 5 |
| Last menstrual period | 2 | 4 | 0 | 6 | 12 |
| Best obstetric estimate | 6 | 0 | 6 | 0 | 12 |
| Other | 0 | 0 | 0 | 2 | 2 |
| No method reported | 11 | 18 | 7 | 25 | 61 |
| Denominator used | |||||
| Live births | 3 | 8 | 2 | 16 | 29 |
| Pregnancies | 1 | 3 | 4 | 8 | 16 |
| Deliveries | 18 | 12 | 7 | 10 | 47 |
a Europe, North America (excluding Mexico), Australia and New Zealand comprise the developed countries category.