The appearance of one-pronuclear human oocytes is associated with a better ovulation-induction response and successful pregnancy outcome.

OBJECTIVE

To study the relationship between the presence of one-pronuclear oocytes in in vitro fertilization (IVF) patients and ovulation-induction response, oocyte and embryo development, and clinical outcome.

DESIGN

Retrospective analysis of 535 consecutive IVF retrievals. Retrievals in which one or more oocytes exhibited one pronucleus were compared with retrievals in which no one-pronuclear oocytes (control) were observed. The following one-pronuclear versus control subgroups were also examined: leuprolide acetate/human menopausal gonadotropin (LA/hMG) ovulation inductions, high estradiol (E2) response cases, and retrievals in which a large number of oocytes (greater than or equal to 15) were recovered.

SETTING

Brigham and Women's Hospital, a tertiary care, university-affiliated hospital.

PATIENTS

Three hundred forty-six IVF patients were treated between January 1989 and May 1991.

MAIN OUTCOME MEASURES

Parameters examined included E2 concentration and number of follicles with maximum diameter greater than or equal to 12 mm on day of human chorionic gonadotropin administration; number of total and mature oocytes retrieved; total fertilization rates; number of embryos; and percent per retrieval of embryo transfers (ETs), clinical pregnancies, and ongoing-livebirths.

RESULTS

The one-pronuclear patients had higher E2 levels and larger number of follicles, yielded significantly more total and mature oocytes, had a higher overall fertilization rate, produced more embryos, and had higher ET, clinical pregnancy and ongoing-livebirth rates per retrieval than did the control patients. Analysis of the subgroup populations revealed no significant differences in the majority of the main outcome measures studied; however, the one-pronuclear patients yielded significantly more total and mature oocytes per retrieval.

CONCLUSIONS

Although there was an increase in the clinical and ongoing-livebirth pregnancy rates (PRs) in one-pronuclear patients, this was probably associated with an improved ovulation-induction response in the one-pronuclear patients. They achieved significantly higher E2 levels, recruited a larger number of follicles, and yielded more oocytes and embryos per retrieval than the control patients. When only the LA/hMG, E2 greater than or equal to 1,500 pg/mL, or the greater than or equal to 15 oocytes/case retrievals were analyzed, the PRs were no longer different; however, the one-pronuclear patients still yielded significantly more total and mature oocytes per retrieval than the controls. Therefore, the appearance of one-pronuclear oocytes is probably associated with the maturation stage of the oocytes obtained and is indicative of an ovulation induction in which a large number of preovulatory, metaphase II oocytes have been recruited.