serum progesterone concentration and ongoing pregnancy rate in frozen-thawed embryo transfers with intramuscular plus vaginal progesterone administration for endometrial preparation

Background: insufficient serum progesterone level in the implantation phase may reduce the rate of pregnancy during freeze embryo transfer (fet) cycles. the present study aimed to evaluate the impact of fet day serum progesterone level on pregnancy outcomes in patients receiving intramuscular plus vaginal progesterone administration for endometrial preparation.methods: based on serum progesterone level on fet day, patients were divided into four quartiles: first ( < 25%), second (26–50%), third (51%–75%), and fourth ( > 75%). there was no significant difference among groups in basal characteristics.results: no statistically significant difference was seen among groups concerning the mean number of retrieved and mature oocytes, embryos transferred, and endometrial thickness (ent). the rate of implantation (p = 0.5), biochemical (p = 0.75), clinical (p = 0.54), and ongoing pregnancy (p = 0.5) were not associated with serum progesterone level on embryo transfer day. conclusion: we found that there is no association between serum progesterone level on et day and pregnancy outcome during fet cycles. it seems that combination therapy using intramuscular and vaginal progesterone, keeps the serum progesterone on et day high enough that eliminates the need for serum progesterone measurement.