Treatment of anovulatory infertility: the problem of multiple pregnancy

The aim of the study was to assess patient, treatment and cyclecharacteristics in relation to the risk of multiple conceptionfollowing ovulation induction in order to reduce the prevalenceof this complication of treatment. We performed a retrospectiveanalysis of 208 pregnancy cycles achieved in the Middlesex Hospitaloutpatient fertility unit. These pregnancies were achieved in175 anovulatory women who conceived after gonadotrophin or pulsatileGnRH therapy. The multiple conception rate was 13.4%. Afterspontaneous reductions and abortions the multiple delivery ratewas 9.6%. Clinical features associated with an increased riskof multiple pregnancies were the presence of polycystic ovarysyndrome and secondary infertility. Comparison between differentprotocols of ovulation induction revealed no relationship withthe risk of multiple conceptions. Although total number of follicleswas increased in the multiple conception cycles, the distributionof follicles according to their diameter on the day of humanchorionic gonadotrophin (HCG) administration was similar inmultiple and singleton conception cycles. Thus, the risk ofmultiple conception could not be attributed to an increasednumber of follicles of any particular size but directly relatedto the total number of the cohort follicles (5=14 mm) and leadingfollicles (>17 mm), rising from 7% with one follicle to 33%with six or more follicles. As we could not find a specificpattern of follicular development that could be associated withmultiple conception, we conclude that the difference in theovarian response leading to multiple conception is quantitativerather than qualitative. The data presented enable the assessmentof the risk of multiple conception in any given cycle.