FSH dose to stimulate different patient' ages: when less is more

To determine the effect of FSH doses on intracytoplasmic sperm injection (ICSI) outcomes according to the age of the patient.

Patients undergoing controlled ovarian stimulation (COS) for ICSI cycles in a university-affiliated in vitro fertilization center were split into age groups: ≤35 y.o. (n=1523); >35 and ≤38 y.o. (n=652); >38 and ≤40 y.o. (n=332); and >40 y.o. (n=370). The effect of FSH dose on COS, laboratorial and clinical outomes was determined by linear regression models.

The FSH dose didn't affect the ovarian response in terms of total number of follicles, retrieved oocytes and mature oocytes within the age groups, but we found that the lower the age, the lower the FSH dose needed per oocyte retrieved. In the group of patients ≤35 y.o., we also found a positive effect of the FSH dose on oocyte yield. Despite that, for patients ≤38 y.o. there was a negative effect of the FSH dose on embryo quality and blastocyst formation rate, and an increase in the cycle's cancelation rate. In patients ≥39 y.o., there were no effects of the FSH doses on the analysed variables.

Ovarian stimulation with high doses of FSH is not recommended in younger women (≤38 y.o.), once we found a decrease in embryo quality and an increase in cycle's cancelation rate. Mild ovarian stimulation protocols may be more appropriate; however, it may not be applicable for women in advanced age, since a higher FSH dose is needed for oocyte retrieval in these patients.