The effect of programmed assistance at parturition on the behaviour of the mother and its offspring in primiparous ewes under extensive rearing was evaluated. Programmed parturition assistance was defined as the manoeuvres performed immediately after the beginning of the expulsion phase to shorten it. Twenty-eight 2-year-old Corriedale primiparous ewes (body condition score (BCS):3.4 ± 0.1; body weight (BW):35.5 ± 0.7 kg) with a single foetus were used. Before lambing and considering BW, BCS and sire, the ewes were randomly assigned to (i) Programmed-parturition-assisted (PPA; n = 14):ewes whose lambing was programmed to be assisted or (ii) Not-assisted (NA; n = 14):ewes that were not assisted and their lambs were born through natural labour. The duration of the foetus expulsion phase, maternal behaviour score (MBS, 1-5), onset of grooming, lamb/ewe BW ratio and lamb desertion were determined in the ewes. Birth weight, Apgar test (score 0-10), O2 saturation, meconium-stained coat, latency to first bleat, success to stand and suck, were registered in the lambs. PPA ewes registered shorter duration of labour (19.2 ± 4.2 vs. 42.6 ± 7.8 min), earlier onset of grooming (1.2 ± 0.4 vs. 3.0 ± 0.6 min), higher MBS (4.5 ± 0.1 vs. 3.1 ± 0.4) and did not desert any lamb during the first 72 h from birth. The lambs born to PPA mothers registered higher O2 saturation (97.6 ± 1.0 % vs. 93.4 ± 1.3 %), bleated earlier (2.4 ± 0.5 vs. 4.6 ± 0.8 min), stood up earlier (24.1 ± 4.2 vs. 36.8 ± 8.0 min) and recorded shorter time to suck (36.5 ± 6.7 vs. 71.0 ± 12.9 min). No effect of treatment on Apgar test or meconium-stained coat was observed, but regardless of treatment, meconium-stained lambs had a higher lamb/ewe BW ratio than unstained ones. The reduction of the duration of foetal expulsion phase, through programmed parturition assistance, positively affected the vigour of the lambs as well as the maternal behaviour of primiparous ewes, which in turn would increase the chances of lamb survival and ultimately, improve the welfare of the ewe-lamb unit. © 2023 Elsevier B.V. All rights reserved.