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

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

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

The IVF unit of a university hospital.

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.

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

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.

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.