The objective of this experiment was to determine the relationship between body condition changes during the 1st 30 d of lactation and the chances of pregnancy following 1st AI in lactating dairy cows. All cows were assigned a body condition score (BCS) value on a 1 to 5 scale (in tenths) within 1 week of calving and 30 d following calving. All cows received timed-AI using G6G/Ovsynch at 75 to 81 DIM. Cows were diagnosed for pregnancy using ultrasonography 35 d following 1st AI. Body condition loss during the 1st 30 d in lactation was greater for 1st and 3rd compared with 2nd parity cows (−0.26 ± 0.01 and −0.26 ± 0.02 vs −0.15 ± 0.01; n = 736). A greater % of 2nd parity cows maintained or gained BCS during the measurement period compared with 1st and 3rd+ parity cows (32 vs. 14 and 19%; n = 736). In 1st and 2nd parity cows there was a significant negative relationship between BCS loss in the 30 d period following calving and chances of pregnancy later in lactation. Cows with the least loss had the greatest pregnancies per AI. There was no relationship between BCS loss and chances for pregnancy in 3rd + parity cows. One of the best predictors for fertility was previous calving interval. Quartiles of cows with a previous calving interval between 343 and 362 and 363 to 407 DIM had less mean ± SEM BCS loss compared with cows that had 408 to 433 and 434 to 619 DIM in previous calving interval (−0.14 ± 0.01, −0.19 ± 0.02, −0.22 ± 0.02 and −0.30 ± 0.03; n = 736), a greater % of cows that maintained or gained during the 30d period (34 vs. 22 vs. 17 vs. 14%; n = 736) and a greater chance for pregnancy at 1st AI (41, 46, 33, and 31%; n = 316). In summary, cows with the least amount of BCS loss between calving and 30 d post-calving had greater fertility following timed-AI at 75 to 81 DIM. Previous calving interval was predictive of BCS loss and future level of fertility.