Frozen Embryos into the Uterus in a Natural Cycle Approach
This method is considered to be an alternative to the previous one. It is conducted during the Surrogate Mother’s natural cycle. In this case there is no need for a Surrogate Mother to take any hormones either during the preparatory phase or after the embryo transfer procedure. This is why this method is much more convenient for Surrogate Mothers.
When this approach is applied, the embryos, which were taken from the Egg Donor and frozen beforehand, are used. It is necessary to freeze the embryos, simply because it is not possible to predict when the uterus of a Surrogate Mother will be ready to accept the embryos nearly until the last minute, though it is generally known 2 to 4 days beforehand.
The cycle of the Surrogate Mother is monitored for follicle growth with the help of an ultrasound, as well as for the characteristic hormonal changes, which take place somewhere around ovulation. Taking these events into consideration and relying on them, the doctors can plan the best day for the embryo transfer procedure. These hormonal changes include the following ones:
The fall in estradiol level;
A LH surge;
The progesterone production;
The follicle collapse.
Therefore, this method has its disadvantages; the main of which is that the frozen embryos are required. And it should be noted, that freezing does not improve odds of embryos, it only reduces them. Generally, in accordance with the investigations conducted, up to 30% of embryos do not survive the process of freezing and thawing. Here comes the risk that no good embryos will remain after the thawing process. Therefore, in case if there are still good embryos, this method can be quite an effective one and much more simple for the Surrogate Mother.
To possible advantages of frozen embryo replacement method the following ones may be referred:
The Surrogate Mother does not have to take any medications;
It is cheaper than the Fresh Embryo Replacement method;
This method requires, of no doubt, to be more “natural” endometrial preparation;
It is possible that there would be dissociation of the cycle of egg retrieval from the cycle of embryo transfer, which makes scheduling much more simple for many couples.
Actually, both methods of the Surrogate Mother’s preparation for the embryo transfer procedure are available nowadays. In case of the first method, fresh embryos are transferred into the endometrial cavities, which are prepared in an artificial way, as for the second one – frozen embryos can be transferred into the cavity during natural menstrual cycles. Both methods have produced comparable pregnancy results, however, each of them has its own advantages as well as disadvantages.
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