Our objective was to assess the association between body condition score (BCS) change and back fat thickness (BFT) during the transition period with pregnancies per AI (P/AI) and health events in Holstein cows in a prospective cohort study. Measurement of BCS and BFT in Holstein cows (n = 645) began ~3 wk before calving, and at 4 ± 3, 25 ± 3, 52 ± 3, 80 ± 3, and 113 ± 3 d after calving. All cows received a timed artificial insemination (TAI) at 80 ± 3 DIM after a Double Ovsynch protocol. Health events included milk fever, ketosis, retained placenta, DA, mastitis, and respiratory disorders. Data were analyzed using logistic regression with GLIMMIX and ANOVA with MIXED procedures of SAS. Changes in BCS before but not after calving were associated with P/AI at first TAI. Cows were grouped based on BCS change (5 point scale; 0.25 point increments) before calving as follows: 1) cows that lost ≥0.5; 2) cows that lost 0.25; and 3) cows that maintained or gained BCS. Change in BCS before calving differed (P < 0.01) among groups and was −0.57; −0.25; and 0.03 for cows in groups 1, 2, and 3, respectively. Change in BFT before calving differed (P < 0.01) among groups and was −2.49, −1.32, and −0.66 mm for cows in groups 1, 2, and 3, respectively. The proportion of cows with ≥1 health event during the first 120 DIM differed (P = 0.01) among groups and was 77% (54/70), 60% (105/174), and 62% (116/186) for cows in groups 1, 2, and 3, respectively. At 32 d after TAI, P/AI differed (P = 0.04) among groups and was 37% (23/62), 48% (73/153), and 55% (92/168) for cows in groups 1, 2 and 3, respectively. Cows with ≥1 health event had fewer P/AI compared with healthy cows [47% (180/379) vs. 64% (127/199), respectively]. The proportion of cows culled by 300 DIM did not differ (P = 0.74) among groups and was 25% (14/56), 27% (36/135) and 23% (33/145) for cows in groups 1, 2, and 3, respectively. We conclude that cows that lost BCS before calving lost more back fat, had fewer P/AI, and had more health events during the first 120 d of lactation. Supported by USDA NIFA Hatch project 231440.