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Dystocia and stillbirth are important sources of economic loss for the dairy industry. The goal of this study was to assess parturient steroids and labor duration as potential risk factors for them. Close-up cows from a Transition Management Facility in Western Wisconsin (n = 78) and from a large dairy in Central Michigan (n = 50) were monitored hourly to identify animals in labor (e.g. mucoid vaginal discharge, calf limbs visible), which were moved into individual maternity pens for videotaping of parturition and recording of calf birth weight (BW) and status (alive, dead) and cow body condition score (BCS). In the Wisconsin cows, calving ease score (CES; 1 = easy to 5 = very difficult) was recorded and a venous blood sample collected within 1 h of delivery for enzyme immunoassay of serum cortisol and progesterone. In both herds, BCS and BW did not associate with calving difficulty. In the Wisconsin cows, progesterone was lower (P ≤ 0.05) in CES 5 cows (378.8 ± 167.2) than in cows with CES 1-4 (mean 1085.6 ± 18.0 pg/ml) with little difference in cortisol, driving the cortisol:progesterone ratio higher (P ≤ 0.05) in the CES 5 cows. All calves from CES 4-5 cows (n = 18) were born dead. In CES 1-3 cows, mean cortisol was higher (P = 0.03) in animals delivering live (22,315 ± 3,921 pg/ml; n = 31) versus dead calves (14,347 ± 2,488 pg/ml; n = 29). The same trend was observed for progesterone (P = 0.11). In the Michigan cows presenting with mucoid vaginal discharge, time to live assisted delivery was 212.2 ± 24.5 min and to dead assisted delivery was 293.1 ± 24.1 min (P ≤ 0.05) but times to live assisted and unassisted deliveries did not differ. Collectively, these preliminary results suggested that parturient concentrations of cortisol and progesterone and labor duration are potential risk factors for dystocia and stillbirth. Future studies will determine if variations in serum steroids are linked to cervical dilation and labor duration, which may underlie dystocia and (or) stillbirth. [ABSTRACT FROM AUTHOR]