The role of progesterone (P) supplementation in the luteal phase of in vitro fertilization (IVF) cycles is well established world-wide , but the influence of the luteal phase estradiol level on implantation is not clearly defined . There is a significant difference in estradiol levels between fertile and infertile cycles of fertile women who underwent donor insemination.

Inclusion Criteria:

• Participants included in this study will have the following criteria : ( 2 of 3 criteria )

  1. advanced maternal age or any other risk factor for POR :

     1. Age ≥35 years
     2. other risk factor of poor responder : ovarian surgery especially in case of endometrioma , chemotherapy, radiotherapy, autoimmune disorders, single ovary, chronic smoking, and unexplained Infertility.

  2. previous poor ovarian response : Number of oocytes at the pickup time 3 or less .

  3. Abnormal ovarian reserve tests :

     1. FSH ≥12 mIu/ml in the early follicular phase .
     2. Estradiol level more than 70 pg/dl in the early follicular phase
     3. Anti-Mullerian hormone (AMH) below 0.5-1.1 ng/ml.
     4. Antral follicle count (AFC) < 5-7 follicles .

Exclusion Criteria:

1. Age >35 with good ovarian response .
2. any intra-uterine pathology can affect receptivity , ( for example ; Sub-mucosal fibroid , intra-uterine adhesions ).
3. Severe male factor infertility.
4. Extended endometriosis (stage 3 or more) .
5. All contraindications for estradiol : venous thrombo-embolism , stroke and breast cancer