Table 2 Deleterious effects of the supraphysiological estrogen levels attained during ovarian stimulation:

1-Effect on the endometrium: most of the available evidence

a: Dys-synchronization of the implantation window.

b: Abnormal Temporal expression of the endometrial pinopodes.

c: Defective endometrial estrogen and progesterone receptors.

d: Impaired endometrial blood flow

e: Abnormal endometrial integrins expression

2-Effect on the developing oocyte

a: Effect on chromosomal and cytogenetic integrity of the oocyte

b: Effect on the mitochondrial function

3-Effect on the sperm causing possible premature acrosome reaction and deactivation

4-Effect on the developing embryo and blastocyst hatching

5-Effect on the ovaries and pituitary (defective corpus luteum function and luteal phase):

a: Defective LH secretion:

- Abnormal LH surge

- Abnormal LH tonic pulse

b: Defective corpus luteum function

6-Other probable targets:

I-Leptin

II-Coagulation system: III-Fallopian tubes

• a: Effect on the ductal environment and ductal fluid

• b: Effect on the ductal transfer and motility

IV-Early developing placenta