In pregnant dairy cows, the hormone kisspeptin‑10 (Kp‑10) first stays steady, rises around day 90‑120, drops again, and then rises one more time near the end of pregnancy. The opposite hormone, GnIH, falls early, climbs later, and both hormones go up together in the final weeks. Other hormones like cortisol stay mostly the same, while estradiol spikes twice.

Recently, two different molecules have been discovered to play an important role in reproduction: kisspeptin (Kp) and gonadotropin inhibiting hormone (GnIH). The aim of this study was to establish the trend of kisspeptin 10 (Kp‑10) and GnIH concentrations, during all phases of pregnancy in cattle, in order to understand their possible role in the physiology of pregnancy. To examine the correlation between these hormones and steroid hormones, cortisol and oestradiol 17β (E2) were also analyzed. Eighty pregnant cows were enrolled and the pregnancy was divided into 8 periods of 30 days each (from 30‑60 days to 240‑270 days). Blood samples were collected from all cows, once only for cow. Kp‑10, GnIH, cortisol and E2 were measured in sera. After an initial plateau, Kp‑10 concentrations increased at 90‑120 days and then decreased until 180‑210 days, undergoing a further increase until 240‑270 days. GnIH concentrations decreased until 90‑120 days, then increased until the end of gestation. These trends were opposing until 180‑210 days, whereat concentrations of both increased until the end of gestation. Cortisol concentrations were homogenous at all times, except at the final period, in which they were higher. E2 showed two peaks, at 90‑120 days and 240‑270 days. The trends in Kp‑10 and GnIH concentrations suggest that these two hormones might act to maintain the delicate endocrine equilibrium of pregnancy.