Objectives were (1) to quantify lying behavior (LB) changes around estrus, and (2) to assess risk factors for reduced changes in LB during estrus, ovulation risk and pregnancy per AI (P/AI). Holstein cows (n = 1,039; 45.6 ± 10.7 kg milk/d) were fitted with pedometers; 1,179 estrus episodes were evaluated. LB measurements were bout frequency (BOUT), total lying time/d (TOTAL), average lying bout duration (AVG), and ratio of lying/standing time (RATIO). Relative changes from d −7 to d −1 (d of estrus) and from d −7 to d +1 were calculated. Thresholds for high intensity estrus were set as a decrease in BOUT >25% and in TOTAL and RATIO >22%. AVG did not change with estrus. Descriptive statistics and logistic regressions were used to analyze the data. At d −1 BOUT, TOTAL, and RATIO were, respectively, 19 ± 34% (−3 ± 5 bouts/d), 20 ± 30% (−145 ± 190 min/d), and 21 ± 26% (−11 ± 21%) lower than at d −7. Major risk factors associated with reduced estrus expression were d 0 progesterone (P4) concentration, season and parity. Cows with P4 < 0.2 ng/mL were twice as likely to have high intensity estrus (large decrease in LB from d −7 to d −1). High intensity estrus increased ovulation rate (OR = 2.7 [BOUT], 4.6 [TOTAL], 4.8 [RATIO]). Cold season also increased ovulation rate (OR = 1.8 [BOUT] and 1.9 [TOTAL and RATIO]). BOUT, TOTAL, and RATIO tended to affect P/AI at 32 and 60 d, but parity, BCS, and season were more important predictors. Interestingly, TOTAL, RATIO, and AVG were greater at d +1 than at d −7 by 8 ± 30% (TOTAL), 10 ± 21% (RATIO), and 13 ± 36% (AVG). When d +1 TOTAL and RATIO were ≥10% d −7 values, there was greater likelihood of ovulation (OR = 2.6 [TOTAL] and 2.4 [RATIO]; 92% vs. 81%). P/AI at 32 d was 1.5 and 1.6 times greater for episodes followed by high d +1 TOTAL and RATIO (38% vs. 27%). BOUT, TOTAL and RATIO could improve the use of information from activity monitors (e.g.: increased estrus detection, fertility prediction). Relationships between P4 at AI, estrus behavior, ovulation and conception should be further investigated.