THE ECOLOGY OF LOW NATURAL FERTILITY IN LADAKH

The existence of very low rates of fertility among non-contracepting h uman populations has intrigued researchers in demography and reproduct ive ecology. Long inter-birth intervals, driven primarily by the lacta tional amenorrhoea associated with breast-feeding, have been shown to be important determinants of low natural fertility in several populati ons. Other reports have suggested that sterility brought about by sexu ally transmitted diseases (STDs) might also explain low fertility in s ome populations, especially in Africa. This report presents an analysi s of 1981 Indian census data that documents low natural fertility in L adakh, a high-altitude region of the Himalaya in north India. In Ladak h, there is evidence for low rates of marriage among women that may be attributable to the practice of polyandry, but also high rates of pri mary and secondary sterility within marriage, resulting in low complet ed parities for post-reproductive age married women. Age-specific fert ility rates derived from the number of current births are also unexpec tedly low. Hypotheses to explain very low fertility in Ladakh are cons idered from among the likely proximate determinants and evaluated usin g two supplementary sources of information derived from fieldwork in L adakh in the early 1990s. The most likely explanations for low marital fertility include sterility from STDs, high rates of fetal loss, and possibly nutritional contraints on ovarian hormone status.