Previous studies suggest that, in pregnancies after in-vitro fertilization (IVF) and embryo transfer following pituitary down-regulation with a gonadotrophin-releasing hormone analogue (buserelin) and ovulation induction with human gonadotrophins, the serum placental protein 14 (PP14) concentration is lower than in normally conceived pregnancies. We studied serum PP14 concentrations in two groups of women: (i) in 17 infertile women whose pregnancy followed IVF and embryo transfer using buserelin (long protocol) and human menopausal gonadotrophin for ovulation induction; (ii) in 15 women whose pregnancy followed transfer of frozen-thawed embryos. Similar PP14 concentrations were found in both groups on days 9-10, 14-15 and 70-77 after human chorionic gonadotrophin administration (buserelin, IVF/embryo transfer) or spontaneous luteinizing hormone surge (frozen-thawed embryo transfer). Our results show that PP14 secretion is not compromised by pituitary down-regulation with buserelin in infertile women with functional ovaries.