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09-01-2011 | Gynaecology | Article

CC-, hCG-induced cycles deliver similar outcomes in normo-ovulatory women


Journal abstract

MedWire News: Researchers have found comparable live-birth and pregnancy rates with human chorionic gonadotropin (hCG)-induced natural or clomiphene citrate (CC)-induced cycles during frozen embryo transfer (FET) in normo-ovulatory women.

"To our knowledge, there are no published studies comparing the natural cycle and the use of CC in FET using exogenous hCG to induce final oocyte maturation," say Dimitra Kyrou (Vrije University Brussels, Belgium) and co-authors.

Using data on 261 hCG-induced natural and 167 CC-induced cycles (50 mg/day, days 3-7) from women aged 37 years on average, the researchers retrospectively compared live birth, ongoing pregnancy, and implantation rates with FET.

Similar live birth, ongoing pregnancy, and implantation rates were seen for hCG-induced natural and CC-induced cycles, at 22.6 and 22.2 percent, 23.0 and 23.4 percent, and 17.9 and 19.8 percent, respectively.

Subgroup analysis for only single-embryo transfer (n = 144) revealed significantly higher pregnancy and implantation rates in the hCG-induced natural compared with CC-induced cycles, at 22.7 versus 8.5 percent, and 21.6 versus 6.4 percent, respectively, although the group numbers were too small to draw definitive conclusions.

The only parameter affecting outcome was the number of embryos transferred, which was significantly higher among the CC group, at 1.72 versus 1.63 embryos (odds ratio = 1.81).

"The major advantage of the hCG-induced natural protocol is that it reduces the inconvenience of an extra drug exposure and the possible risks linked to CC administration," conclude the researchers.

MedWire ( is an independent clinical news service provided by Current Medicine Group, a trading division of Springer Healthcare Limited. © Springer Healthcare Ltd; 2011

By Ingrid Grasmo