Infertility is a significant global problem affecting 1:7 worldwide. An estimated 24% of couples had no detected conception within 12 and 24 months of unprotected intercourse on a nation-wide representative sample of couples from the general population. Unexplained infertility is one of the most frequent infertility diagnoses given to women, encompassing up to approximately 30% of all cases.
Unexplained infertility refers to couples who fail to conceive, even though the female ovulates normally, has no obvious abnormalities in the reproductive tract, and the male is producing an adequate number of motile sperm. Nowadays, there are plenty of infertility treatments available, however many assisted reproduction techniques like IVF are very expensive and not often covered by insurance; therefore IVF is an option less commonly offered.
Women with unexplained infertility are commonly treated with drugs for ovarian stimulation. During this procedure the ovaries release an egg and sperm is directly inserted into the uterus. This is a quite successful treatment and definitely less costly. Letrozole, gonadotropins and clomiphene citrate are the drugs most commonly used for ovarian stimulation.
Unfortunately, medication for ovarian stimulation has its side effects and can be complicated by ovarian hyperstimulation syndrome, which results in multiple pregnancies with increased risk of preterm birth. The challenge is to determine which medication is best at achieving and maintaining pregnancy while reducing multiple pregnancies.
In a recent study, scientists assessed the frequency of multiple pregnancies among women with clinical pregnancies. Women age 18 to 40 who were ovulating and had at least one Fallopian tube were treated with letrozole, gonadotropins or clomiphene for up to four cycles, comparing the outcome for the three drugs. According to the study, ovarian stimulation with letrozole resulted in significantly lower frequency of multiple pregnancies, but also a lower frequency of live births, as compared with gonadotropins, but not as compared with clomiphene. Therefore, scientists concluded that clomiphene citrate is the most appropriate means to stimulate ovulation in unexplained infertility treated with intrauterine insemination (IUI).