[en] To measure effects of early tritium-induced oocyte loss on lifetime reproduction, we determined total reproductive capacity (RC) of female mice in which known oocyte deficiencies had been produced in early life by chronic exposure to ³HOH administered to their mothers in drinking water from the day of conception to 14 days postpartum. At that time ³HOH administration was stopped, and oocytes were enumerated in the suckling young. Over the subsequent two years, RC was determined in these young by counting the litters and offspring they produced during continuous breeding over their entire reproductive life spans. Offspring were removed at birth to avoid interrupting the breeding process. Tritium-induced diminution of RC was found to be done dependent but less than - and, interestingly, different from - diminution of oocyte number. Oocyte loss was stochastic; RC reduction, nonstochastic. Also, despite oocyte deficiencies, productivity of exposed females tended to be normal during early reproductive life but failed prematurely as oocytes ran out. 15 refs., 4 figs., 3 tabs