The Follicular Output Rate was Improved with 3-Day Letrozole Administration Compared with 5-Day Letrozole Administration Under Progestin-Primed Ovarian Stimulation.

PURPOSE: Progestin-primed ovarian stimulation (PPOS) has been widely employed in in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) cycles. In recent years, letrozole (LE) combined with medroxyprogesterone acetate (MPA) has been used in this protocol to enhance ovarian response. This study compared the effects of a 5-day regimen with those of a 3-day regimen of letrozole within PPOS, focused on the follicular output rate (FORT) and blastocyst formation rates.

PATIENTS AND

METHODS

From January 2017 to January 2020, 1,754 infertility patients who received PPOS protocol were divided into two groups: 577 patients received 2.5 mg/day LE for 5 days (LE 5-day), and 1177 patients received the same dose of LE for 3 days (LE 3-day). Propensity score matching (1:1) balanced confounders, yielding 489 patients per group. The primary outcoms was the FORT. The rate of blastocyst formation was evaluated as the secondary outcome. A multivariable logistic regression analysis was performed to compare the disparity in the FORT between the two groups.

RESULTS

After matching, the number of oocytes retrieved, number of mature oocytes, number of blastocysts, blastocyst formation rates, FORT, and clinical pregnancy rates were more favourable in the LE 3-day group than in the LE 5-day group (P < 0.05). In the multivariable linear regression model, after making adjustments for factors such as age, anti-Müllerian hormone (AMH), antral follicle count (AFC), body mass index (BMI), infertility type, and basal P, patients in the LE 3-day group exhibited an increase in the FOTR (β = 0.08, 95% confidence interval [CI] 0.02 to 0.14, P = 0.0082) and blastocyst formation rate (β = 0.23, 95% CI 0.17 to 0.29, P < 0.0001) compared to those in the LE 5-day group.

CONCLUSION

Compared with LE administration for 5 days, LE administration for 3 days may increase the FORT and the rate of blastocyst formation.