Hi

I believe it  should be started for both following the LH surge (early luteal phase).

Regards,

Bassem

Dear Jain

I would to explain the FET protocol, usually  we start  GnRH from day 21 of previous cycle till the patient down-regulated( E2 LESS THAN 70 pg/dl and Endometrial thickness less than 5, then start E2 at least 6 mg daily and you can rise the dose if the response sub-optimal till the End.thickness of 8 or more mm then add progesterone in form of vaginal supp. 400mg BID and consider this as the day of egg collection ( from her you can indicate the transfer day)

If you going to do FET  using natural cycle, start to check for ovulation by LH surge kit ( usually depend of the cycle frequency, but generally start checking from day 10), once early morning urine sample positive for LH. the consider the egg collection day 24 hrs later and start progesterone as above.

hope this to be useful1

Progesterone rises significantly a day before pick up. Hence the age of the embryo plus 1 should be the number of days that matches the natural synchrony between embryo and endometrium.