It’s not clear exactly what is to blame. About 20 to 30 per cent of infertility cases are due to male factors, 20 to 35 per cent are due to female, and 25 to 40 per cent are due to combined problems in both parts. Up to 20 per cent of cases remain ‘unexplained’.
Haijulikani ni nini hasa cha kulaumiwa. Takriban asilimia 20 hadi 30 ya kesi za ugumba zinatokana na sababu za kiume, asilimia 20 hadi 35 ni za wanawake, na asilimia 25 hadi 40 zinatokana na matatizo ya pamoja katika sehemu zote mbili. Hadi asilimia 20 ya kesi zinabaki kuwa 'zisizoelezewa'.