KISS1 and spontaneous abortion: The death of a single fetus during twin pregnancy significantly reduced MoM kisspeptin and MoM hCG to levels comparable with successful singleton pregnancy (MoM kisspeptin: 1.06 ± 0.42, singleton, no miscarriage; 1.15 ± 0.58, twin pregnancy with miscarriage of one fetus, P = NS vs singleton, no miscarriage) (MoM hCG: 1.08 ± 0.47, singleton, no miscarriage; 1.23 ± 0.84, P = NS vs singleton, no miscarriage) (data not shown).