Sahin ME, Madendag IC, Sahin E, et al. - Researchers examined if women with unexplained infertility differed from fertile women in terms of the progesterone-induced blocking factor (PIBF) level. They performed a cross-sectional study including 46 healthy participants (volunteers between 18 and 35 years) and divided them into two groups—the unexplained-infertility group and the control group. Among participants, 22 had unexplained infertility. Observations revealed significantly lower serum PIBF levels in unexplained-infertility group vs the fertile control group.