Endometrial preparation

The ROPA method consists of two parts: the partner that donates her eggs must go through ovarian stimulation and egg retrieval, while the other partner will undergo hormonal treatment which will improve her endometrial lining in order to receive an embryo during the implantation process.

Why prepare the endometrium?

The endometrium is the innermost layer of the uterus and it plays a fundamental part in the gestational process and during pregnancy.

Endometrial thickness varies throughout the menstrual cycle. Implantation can only occur during certain days of the cycle, this is known as the “implantation window”, generally within the 19th-21st day of the cycle. If the embryo hasn’t been implanted then the endometrium disappears in the form of menstruation.


Endometrial preparation consists of undergoing a hormonal treatment which imitates and optimises the natural cycle. This facilitates the implantation of the embryo and the chances of pregnancy.

The treatment is usually composed of progesterone and estrogen, which, depending on the type of medication may be given orally or via vaginal ovules or patches.

Endometrial preparation is key for the ROPA method. Estrogen is administered on the first days of the menstrual cycle and then progesterone is given on fertilisation day.

This medications may have some minor side effects such as bloating, fatigue and increased vaginal discharge.

Factors that contribute to a successful implantation

Optimal endometrium: when the lining is within 7 to 10 mm and contains three layers (triple-line endometrium) the chances of pregnancy are high.

Embryo quality: implantation is more likely with good quality embryos.

Endometrial receptivity: the implantation window may be too early or too late.

Also, the day the embryo develops and the endometrial receptivity must be perfectly synchronised.


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