Conception rate after in vitro fertilization in patients who conceived in a previous cycle.

OBJECTIVE

To evaluate whether a previously successful in vitro fertilization and embryo transfer (IVF-ET) cycle is a favorable prognostic factor for a subsequent cycle.

DESIGN

A retrospective comparison between current IVF patients who have previously conceived in an IVF versus natural cycle.

SETTING

The IVF unit of a university hospital.

PATIENTS

Group A consisted of 51 patients (70 cycles of IVF-ET) who previously conceived in an IVF-ET cycle, and group B included 141 patients (201 cycles of IVF-ET) who previously conceived in a natural cycle. All couples with male factor infertility were excluded. Ovulation induction protocol was identical for both groups and consisted of gonadotropin-releasing hormone agonist pretreatment followed by gonadotropin stimulation.

MAIN OUTCOME MEASURES

Pregnancy rate per ET, cumulative pregnancy rate, and livebirth rate in both groups.

RESULTS

The following parameters were comparable for both groups: age, menotropin dosage required for an adequate stimulation, ovarian response, mean number of oocytes retrieved per cycle, fertilization and cleavage rates, and the mean number of embryo transferred. Group A attained a significantly higher pregnancy rate (PR) than group B (31.4% versus 19.4%). Group A also achieved a significantly higher livebirth rate (22.9% versus 11.4%) than group B. Similarly, the cumulative PR curves and the cumulative livebirth rate curves for three consecutive IVF-ET cycles differed significantly between the two groups.

CONCLUSION

A previous successful IVF cycle is a positive prognostic factor for a repeated IVF attempt. This effect could be because of either an improved endometrial response or a better embryo quality. It may be that this patient population is relatively immune to the known untoward effects of ovulation induction on endometrial development and, therefore, may represent a potential clinical model that can be used to further identify the factors influencing uterine receptivity after ovulation induction.