CONTRALATERAL OVULATION SHORTENS FOLLICULAR PHASE LENGTH AND FAVORS PREEMBRYO DEVELOPMENT DURING OVARIAN STIMULATION WITH CLOMIPHENE CITRATE

The present study was undertaken to evaluate whether the site of ovula tion affects the following follicular phase length and pre-embryo deve lopment during infertility treatment with ovarian stimulation using cl omiphene citrate. a total of 363 cycles in 97 patients undergoing infe rtility treatment (182 intrauterine insemination (IUI) cycles in 60 pa tients and 181 in-vitro fertilization (IVF) cycles in 52 patients) wer e studied, The cycles mere divided into two main groups: preceding uni lateral ovulation (PUO) and preceding bilateral ovulation (PBO), In th e PUO group, the cycles were subdivided into contralateral ovulation, bilateral ovulation and ipsilateral ovulation, In IVF cycles alone, bi lateral ovulations mere further divided into bilateral ovulation-contr alateral side and bilateral ovulation, ipsilateral side, Contralateral ovulations were seen in 134 of 240 cycles (56%), excluding bilateral ovulation and PBO, The follicular phase length in contralateral ovulat ion (16.2 +/- 2.6 days, mean +/- SD) was significantly (P < 0.05) shor ter than that of ipsilateral ovulation (16.9 +/- 2.8). There were no s ignificant differences of follicular phase length among contralateral ovulation, bilateral ovulation and PBO, Of IVF cycles including contra lateral ovulation-ipsilateral ovulation and bilateral ovulation a tota l of 107 preovulatory follicles was assessed in the contralateral side (contralateral ovulation + bilateral ovulation-contralateral side) an d 97 in the ipsilateral side (ipsilateral ovulation + bilateral ovulat ion, ipsilateral side). The oocyte retrieval rate (88%), fertilization rate (84%), cleavage rate (95%), embryo transfer rate (70%) of contra lateral follicles were higher than those of ipsilateral follicles (71, 62, 86, 38% respectively) and those of PBO (76, 62, 87, 41% respectiv ely). The total pregnancy rate of both IUI and IVF did not differ amon g contralateral ovulation (15%), ipsilateral ovulation (8%), bilateral ovulation (11%) and PBO (10%). The results confirm and extend our pre vious findings in natural cycles, suggesting that local ovarian factor s, e.g. from corpus luteum, affect the health of preovulatory follicle and the enclosed oocyte in the same ovary (ipsilateral) negatively, C ontralateral selection of preovulatory follicles in the succeeding cyc le shortens the follicular phase length and favours pre-embryo develop ment, The chance of conceiving during ovarian stimulation with clomiph ene citrate may thus be affected by the site of ovulation in the previ ous cycle.