[Intrauterine insemination: spontaneous or medically-assisted ovulation?]

Intrauterine insemination (i.u.i.) is usually proposed as the first-line therapy for infertility related to cervical factor, male and unexplained infertility. The overall success rate of i.u.i. is about 10-20% clinical pregnancies per cycle. i.u.i. may be performed in patients with or without prior controlled ovarian hyperstimulation (COH). The aim of COH is to closely monitor follicular growth in order to achieve a timely triggering of ovulation and i.u.i. Additionally, ovarian stimulation allows to increase the number of developing follicles. According to the review of previous prospective randomized studies and meta-analyses, it seems that: (i) when a cervical factor is involved, the advantage of COH in conjunction with i.u.i. is likely but has to be confirmed; (ii) in male infertility, COH with gonadotropins in conjunction with i.u.i. increases the clinical pregnancy rate by two. In this situation, the better the sperm parameters are, the more advantageous COH is; (iii) in unexplained infertility, COH in addition to i.u.i. improves the pregnancy rate but stimulation with clomifene citrate appears to be less effective than gonadotropins administration. Beside the sperm parameters, the success rate depends on both woman's age and degree of ovarian stimulation. Meanwhile, ovarian hyperstimulation exposes to the risk of multiple pregnancy and hyperstimulation syndrome. Increasing the number of preovulatory follicles from one to two allows to approximately double the pregnancy rate. However, there is clear evidence that getting three or more than three follicles exposes to a worrying risk of multiple pregnancy. At the present time, the successful outcome of i.u.i. should not be assessed by the clinical pregnancy rate any longer but by the singleton birth rate. Our therapeutic strategy for COH prior to i.u.i. should take into account woman's age, infertility duration and associated infertility factors. The objective in terms of preovulatory follicle number must be determined prior to the stimulation in order to optimise the cycle outcome with a singleton birth.