The purpose of this study is to determine if pretreatment with Estrogen can assist in the planning and programming of In Vitro Fertilization treatments.

A randomised controlled trial in which study group will be given estrogen derivative before ovarian stimulation in GnRH antagonist protocol and compared to the classical GnRH agonist protocol.Estrogen will be given P.O , "PROGYNOVA' , in a dose of 2 mg /d, starting day 2 of menses and until first Monday to follow. Main outcome measure will be ability to control the ovum pickup day, calculated as a rate of ideal pickups divided by the entire pickup number. All women enrolled will be under 38 years of age, with a clear indication for IVF other than ovulatory dysfunction. women with past 4 treatment failures will be excluded as well as cases in which sperm achieved in surgical methods.

Inclusion Criteria:

• IVF treatment in the following indications: Male, Mechanical, Unexplained
• Age<38 years
• Treatment Cycle number 1-4

Exclusion Criteria:

• Ovulatory disorder as an indication for IVF
• Repeated failure in previous IVF treatments (> than 4 cycles)
• Sperm used for treatment was retrieved by surgical procedure