Circulating placental protein 14: in the first trimester of spontaneous and IVF pregnancies.

Circulating placental protein 14 (PP14) levels were measured during the first trimester in three groups of pregnant women: (i) natural conception (n = 15); (ii) pituitary desensitization with buserelin and ovarian stimulation with human menopausal gonadotrophin (HMG) followed by in-vitro fertilization and embryo transfer (IVF-ET) (n = 15); and (iii) ovarian stimulation with clomiphene citrate and HMG, followed by IVF-ET (n = 16). A 7- to 8-fold increase in serum PP14 levels was observed in normal pregnancies between weeks 4 and 10. This increase was earlier and less marked in group (ii) and absent in group (iii). These findings support the concept that endometrial function is altered in pregnancies achieved following ovarian stimulation. Alternatively, if the ovary is an important source of PP14, then these data suggest that in contrast to ovarian synthesis of steroids and the peptide relaxin, ovarian stimulation results in an impairment of PP14 synthesis, and that this is most marked when clomiphene citrate has been used.