Relation between pregnancy-associated plasma protein A (PAPP-A) in human peri-ovulatory follicle fluid and the collection and fertilization of human ova in vitro.

In 42 patients, blood-free peri-ovulatory follicular fluid was aspirated from 86 follicles for estimation of pregnancy-associated plasma protein A (PAPP-A) and related to several variables associated with the fertilization of human ova in vitro. Follicle growth was stimulated by clomiphene citrate alone or in combination with human menopausal gonadotrophin (hMG) and ovulation was triggered by human chorionic gonadotrophin (hCG) except in six patients who had a spontaneous surge of luteinizing hormone (LH). PAPP-A was detected in 83 of the 86 follicles aspirated, ranging from 'undetectable' to 1044 micrograms/l. The concentration of PAPP-A was statistically significantly correlated with increasing follicle size, follicular oestradiol-17 beta concentration and oocyte recovery. At PAPP-A concentrations of greater than 200 micrograms/l, there was no correlation noted with the ability of the ovum to be fertilized, to cleave, or between PAPP-A levels in follicles from pregnant and non-pregnant cycles. There was no significant difference in the mean PAPP-A concentration for the two stimulation regimens, but concentrations were greater in follicular fluid from patients who surged spontaneously (P less than 0.001). It appears PAPP-A levels may provide an index of follicle maturity but not of the pregnancy potential of the ovum.