Genetically obese (O) or lean (L) primiparous gilts were assigned on the day of mating to an adequate [control (C) or restricted (R)] intake of feed. Body weight and ultrasonically estimated backfat depth were recorded at wk 0 (mating), 4, 8, 12 and 16 of pregnancy, and at d 2-3, 21 and 28 of lactation. Number of pigs born, survival rate to 28 d of age and piglet body weight at 0, 14, 21 and 28 d of age were recorded. Four male and four female progeny from each diet group of each genetic strain were slaughtered at 6 mo of age for carcass and organ weight measurements. OR and LR gilts responded similarly to feed restriction in body weight change, backfat depth and plasma traits. Body weight increased throughout gestation in OC and LC gilts but decreased about 6 kg in OR and LR gilts. Backfat remained relatively constant throughout gestation in OC and LC gilts but declined steadily in LR and OR gilts. There were no genetic group x diet interactions for any trait measured. Litter size and piglet survival were not affected by diet or genetic group, but piglet birth weight and daily gain to d 28 and to wk 25 were lower in both R groups. Backfat accretion and other indices of carcass fatness were reduced in progeny of R dams.(ABSTRACT TRUNCATED AT 250 WORDS)