The aim of this summary is to provide new insights into the use of data from estrus events and automated activity monitors as a tool to predict fertility. Recently, more studies have demonstrated how estrus events and intensity is associated with ovulation, ovarian and uterine function, and fertility. In one study, the likelihood of ovulation was greater for high vs. low relative increase estrus, but a more detailed experiment also showed slight differences in the timing of ovulation. Expression of estrus near AI also modified the expression of genes related with the immune system, adhesion molecules and prostaglandin synthesis in the endometrium (MX1, MX2, MYL12A, MMP19, CXCL10, IGLL1, SLPI, OTR and COX-2) and those related with apoptosis, P4 synthesis and prostaglandin receptor (CYP11A, BAX and FPr) in the CL. The expression of estrus (yes vs no) was associated with increased P/AI for timed-AI (38.9 vs. 25.5%) and embryo transfer (46.2 vs. 32.7%) protocols. Moreover, there was a decrease in pregnancy loss in both programs. Data from other recent studies involving spontaneous and induced estrus have shown that greater relative increase and longer duration of estrus, captured by different activity monitors, significantly improve P/AI (over 12% points across different studies). Intensity and duration of estrus were correlated with BCS, parity, milk production and secondary behavior signs as expected, but surprisingly not associated with follicle diameter and concentration of estradiol at estrus. Collectively, ovulation could partly explain the observed reduction in fertility, but it is clear that the endometrium and the CL play an important role. Quantitative information from estrus events could be used to improve estrous detection quality and develop decision-making strategies at the farm level. Further studies in this field should aim to 1) better understand ovarian, embryo and endometrium mechanisms associated with either the expression or intensity of estrus and, 2) refine the collection of phenotypes related to estrus (i.e., relative increase, absolute increase, baseline levels, duration, and repeatability within cow) to improve estrous detection and possibly genetic selection.