Evaluation of serum anti-Müllerian hormone (AMH) and equine chorionic gonadotrophin (eCG) concentrations in pregnant mares in relation to foetal sex

The aim of this study was to investigate the foetal sex related difference and progression in maternal serum anti-Müllerian hormone (AMH) and equine chorionic gonadotrophin (eCG) concentrations during different points of time in pregnant Arabian mares. The study groups formed by 12 healthy male offspring- and 12 healthy female offspring-foaling mares, designated as group MFM and group FFM, respectively. Peripheral blood samples were collected on the day of natural mating and then monthly until the 6th month (mo) of gestation. Serum AMH was measured in all serum samples; eCG was measured in samples collected from 2 to 5 months Of gestation. Serum AMH concentrations of group FFM at mo 4 and mo 5 (3.89 ± 0.49 ng/ml; 2.89 ± 0.32 ng/ml), were significantly higher than in group MFM (2.11 ± 0.46 ng/ml; 1.87 ± 0.32 ng/ml), (P < 0.05). The mo of gestation (mo 1–6) had no effect on serum AMH concentrations of either group MMF or FFM (P > 0.05). Serum eCG concentrations of group FFM at mo 2 (359.73 ± 41.51 mIU/ml), were significantly higher than in group MFM (255 ± 21.18 mIU/ml) (P < 0.05). Group-time interaction for eCG concentrations at mo 2–4 was non-significant (P > 0.05). Concentrations of serum AMH showed no relationship with corresponding eCG levels at mo 2–4 (P > 0.05). Individual variations in AMH and eCG concentrations and the inability to determine a cut-off point for determination of foetal sex make these hormones unlikely candidates for determining foetal sex in the mare.