Infertility and spontaneous abortion
General categories of infertility, by developing status and region (WHO study)
| Categories | Developed countries | Africa | Asia | Latin America | East Mediterranean | 
| Became pregnant | 12 | 15 | 16 | 13 | 15 | 
| No cause found in both | 14 | 5 | 13 | 10 | 3 | 
| Female cause only | 31 | 37 | 34 | 25 | 25 | 
| Male cause only | 22 | 8 | 13 | 22 | 19 | 
| Causes found in both | 21 | 35 | 24 | 30 | 38 | 
Cates W, Farley TMM, Rowe PJ. Patterns of infertility in the developed and developing worlds. In: Rowe PJ, Vikhlyaeva EM, editors. Diagnosis and treatment of infertility. Toronto: Hans Huber Publishers; 1988. p. 57-67.