Changes induced in serum protein profiles by ovarian stimulation during in-vitro fertilization-embryo transfer treatment: a comparison between conception and non-conception cycles

The profiles of plasma protein concentrations during the follicular phase in unstimulated women and in women undergoing ovarian stimulation for in-vitro fertilization-embryo transfer (IVF-ET) treatment are described. Plasma protein concentrations are correlated with those of total oestradiol (protein-bound and free) and total progesterone. In addition, 10 conception cycles and 18 non-conception cycles are compared in an attempt to identify predictors of successful treatment. Ovarian stimulation caused a significant increase in follicular phase in serum concentrations of sex hormone binding globulin (SHBG), cortisol binding protein (CBP) and insulin-like growth factor binding protein 1 (IGFBP1). In contrast no increase was observed in unstimulated cycles. Serum levels of endometrial protein PP14 decreased significantly during the follicular phase in both stimulated and unstimulated cycles. Levels of pregnancy zone protein (PZP) were more than doubled at the time of oocyte aspiration compared to the unstimulated cycles. Albumin concentrations were unchanged by the stimulation. Throughout the follicular phase, levels of SHBG were significantly higher, and total oestradiol significantly lower in women who became pregnant, than in those who did not. Therefore, a low concentration of free, biologically active oestradiol seemed to favour pregnancy, as the concentration of albumin is similar in the two groups. The endometrial protein PP14 was significantly lower during the follicular phase in conception than in non-conceptional cycles. On day 2 of the treatment cycle, the PP14 concentration showed a 75% correct prediction of conception and non-conception cycles. These results suggest that levels of PP14 may predict successful IVF cycles even before hormonal treatment is commenced.