Low dose human chorionic gonadotropin alone can complete follicle maturity: successful application to modified natural cycle in vitro fertilization

Low-dose human chorionic gonadotropin can be used to complete follicle maturity after gonadotropin releasing hormone antagonist administration in the late follicular phase of a natural cycle, leading to successful pregnancies in modified natural cycle in vitro fertilization.


Richard J. Paulson, M.D., Karine Chung, M.D., M.S.C.E., Alexander M. Quaas, M.D., Ph.D., Sara J. Mucowski, M.D., Sami I. Jabara, M.D., Kristin A. Bendikson, M.D.

Volume 105, Issue 5, Pages 1228-1231



To investigate the feasibility of utilizing low-dose hCG alone to complete follicle maturity in a natural cycle, without the need for antecedent exogenous FSH stimulation.


Case series.


Academic fertility program.


Normally ovulatory women with infertility thought to be predominantly due to male factor.


Modified natural IVF cycles were conducted as follows: natural ovulatory cycles were monitored with serial ultrasound examinations and serum E2 determinations. When the lead follicle reached preovulatory status according to cycle day, ultrasound, and E2 levels, 0.25 mg of the GnRH antagonist ganirelix acetate was administered along with 200 IU of hCG. These medications were repeated daily for 2 to 3 days with further serial monitoring. A trigger dose of 10,000 IU of hCG was followed by follicle aspiration, IVF, and ET in a standard manner.

Main Outcome Measure(s):

Follicle maturity, live births, documentation of the feasibility of this new approach.


In all cases, E2 levels rose and the dominant follicle continued to increase in size in response to low-dose hCG after GnRH antagonist administration. Follicle aspiration yielded one or more mature oocytes. In vitro fertilization and ET resulted in live births.


Low-dose hCG can be used to complete follicle maturity in a natural cycle without the need for antecedent exogenous FSH stimulation. This finding may have strong clinical utility in modified natural cycle IVF.

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