While often undiagnosed due to the absence of clinical signs and the price tag associated with collecting blood samples required for diagnosis, subclinical hypocalcemia (SCH) affects nearly 45 percent of multiparous dairy cows. Traditionally, one day in milk (DIM) was thought to be the opportune time to diagnose SCH; however we have recently discovered that decreases in blood calcium occurring at four DIM are more closely associated with lower milk production, reduced feed intake, and an increased risk for additional disease development. Although we understand the negative effects of SCH, particularly episodes occurring at four DIM, on future health and milk production, its effect on reproductive success is largely unknown. Results from past reports are inconsistent, likely due to the range of days in which SCH was diagnosed, as well as the variation in calcium cutpoints used for diagnosis. As successful and efficient reproduction is critical for the success of dairy operations, we were interested in exploring the association of SCH occurring at four DIM with the odds of pregnancy to first service and the time from calving to pregnancy.