A more effective treatment to trigger ovulation

The current study examined the safety and efficacy of letrozole (Femara) for ovulation induction in women with polycystic ovarian syndrome.

Polycystic ovarian syndrome is the most common cause of infertility due to non-ovulation. The first treatment for women with polycystic ovarian syndrome trying to achieve pregnancy is clomiphene citrate (Clomid), which stimulates ovulation. However, clomiphene results in only a 22% live birth rate, a 3–8% rate of multiple pregnancy (twins for example), side effects such as mood changes and hot flashes, and a higher risk of ovarian hyperstimulation syndrome; painful, swollen ovaries which can lead to fluid leakage into the abdomen or chest.

Aromatase inhibitors, such as letrozole (Femara), are thought to be more likely to induce ovulation with a single egg (which lowers the risk of multiple pregnancies and ovarian hyperstimulation syndrome) and fewer side effects. It is not clear, however, whether letrozole has an effect on the developing fetus. The current study examined the safety and effectiveness of letrozole in comparison to clomiphene in women with polycystic ovarian syndrome.

In this study, 750 women with polycystic ovarian syndrome undergoing ovulation induction therapy were randomly assigned to receive either letrozole or clomiphene. Treatment began on Cycle day 3 and continued for 5 days. The primary outcome measured was the rate of live birth. Participants who conceived following treatment were invited to have their child examined and followed for up to 3 years following birth to determine any developmental effects related to treatment.

Letrozole resulted in a 27.5% live birth rate, which was significantly higher than the 19.1% live birth rate following clomiphene. Letrozole also resulted in an 88.5% ovulation rate and a 41.2% conception rate, both significantly higher than the 76.6% ovulation rate and 27.4% conception rate following clomiphene.

Letrozole was more likely to cause fatigue and dizziness, while clomiphene was more likely to cause hot flashes. There were no significant differences between the treatments for pregnancy complications such as gestational diabetes, preeclampsia (high blood pressure during pregnancy), or preterm birth. There were no significant differences in post-birth complications, which included jaundice (yellowing of the skin caused by liver or bile duct damage) or respiratory distress syndrome, which generally occurs in preterm infants whose lungs did not fully develop.

This study concluded that letrozole was associated with a higher ovulation, conception, and live birth rate compared to clomiphene in women with polycystic ovarian syndrome.