ABSTRACT In the present work, the effects of undernutrition of beef cows during early pregnancy on their productivity in the short, medium and long term were studied. Thus, 115 cows (Brown Mountain and Pyrenean breeds) were used and they were oestrous synchronizeted, and then managed with a protocol of fixed time artificial insemination 11 days later (76 ± 14 days postpartum). During the first third of pregnancy, cows received a diet 100% (CONTROL) or 65% (SUBNUT) of their energy requierements; the rest of the pregnancy period and during the following lactation all cows received a diet that supply 100% their requirements. The imposed maternal undernutrition did not affect fertility (77.4%); however, undernourished cows lost live weight and body reserves during the first third of gestation. Maternal undernutrition also caused lower growth in calves that were simultaneously raising undernourishment. Six months after the end of the maternal feeding treatment, the undernourished cows had a lower body condition at calving, which affected the majority of parameters analyzed in the cows and their offspring. All cows lost weight during the following lactation, except for the undernourished Pyrenees, who maintained their live weight; on the contrary, their calves had the lowest growth, the lowest weaning weight (21% less) and the lowest IGF-1 values (closely related to animal development). This experiment confirmed that early maternal undernutrition has short, medium and long-term effects on cows, on calves raised and on offspring gestated during such undernutrition.