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Treatment with thawed, fertilised eggs (frozen embryo treatment)

If you have eggs (embryos) in the freezer, they’ll have been cultured for 5-6 days in the laboratory and are now known as blastocysts. These eggs have a high chance of resulting in pregnancy and can best withstand the freezing procedure. On average, 1/3 of the fertilised eggs reach this stage of development.

At the clinic, the laboratory employs a special freezing method – vitrification, which we began using in 2006 as the first clinic to do so in Denmark. The method has now gravitated to the rest of Denmark due to our good results, as well as experience with the method internationally. Vitrification involves flash-freezing the eggs, whereby the minimum possible damage occurs during the freezing process.

In our experience, >95 % of the eggs survive the thawing process.

You must remember that we’re not allowed to thaw your eggs unless we’ve received a written consent from you to do this. This request (thaw declaration) must be signed by both parties, or in the case of treatment of single women, by this party. The thaw declaration can be downloaded on our website (under the menu: “documents”).

Registration for frozen embryo treatment

On your first day of menstruation, you must call IVF-SYD on tel. +45 76 24 50 20 from 9.15-12.00 or 12.30-14.30 and sign up for treatment. If your menstruation begins on a Friday after 14.30 or during the weekend, you can call on the following Monday during telephone hours.

On your first day of bleeding you begin with Østradiol 2 mg, (3 tablets at night time). Østradiol builds up the mucous membrane on the uterine wall and enables it to receive the egg.

You report for a scan 10-12 days after beginning a course of Østradiol. This enables the mucous membrane of the uterus to be measured. If things look fine and the membrane has a thickness of more than 7 mm, you must – according to the nurse’s instructions – begin a course of Crinone (3 x per day) and continue with Østradiol. Thawing and embryo transfer take place on the 6th Crinone day.

Embryo transfer

If, contrary to expectations, the egg hasn’t survived the thawing process, we’ll contact you on the morning concerning the cancel of the embryo transfer.

If the egg has survived, however, you just need to observe your appointment for embryo transfer. Remember to make sure that your bladder is HALF FULL!

Following embryo transfer, you have to continue with both Østradiol and Crinone until your pregnancy test 14 days later. If this test is positive, you continue with both Østradiol and Crinone until the 10th week of pregnancy. The hormones don’t affect the foetus.

A pregnancy scan is conducted 3-4 weeks after a positive test.

If the test is negative, treatment with Østradiol and Crinone is stopped and bleeding will occur within a few days. If there are more eggs in the freezer, treatment can start over again according to agreement with the clinic.

Registration for treatment in spontaneous cycle.

On your first day of menstruation, you must call IVF-SYD on tel. +45 76 24 50 20 from 9.15-12.00 or 12.30-14.30 and sign up for treatment and make an appointment for a scan on the 10th-12th day of your cycle (depending on the length of your cycle). If your menstruation begins on a Friday after 14.30 or during the weekend, you can call on the following Monday or on one of the following days during telephone hours. You can also register by mail (

The schedule in the case of treatment for a woman with a 28-day cycle is typically as follows:

Scan on the 10th-12th day with measurement of the dominant follicle; Ovitrelle injection on the 14th day; thawing and embryo transfer on the 21st day. Supplement of Ovitrelle with 12 clicks on the day of embryo transfer and 12 clicks 4 days later in order to ensure appropriate hormone production. The Ovitrelle must be kept in the refrigerator. You can administer the injections at any time of the day.

If the pregnancy test is positive, a pregnancy scan is conducted 3-4 weeks later.

What are the chances of pregnancy with a frozen eembryo (blastocyst)?

The clinical pregnancy rate with one blastocyst (cultured for 5 days) is 30-35 %, which is the same as if we implanted 2 fertilised eggs (cultured for 2-3 days). The pregnancy rate depends on the age of the woman and the appearance of the blastocyst, however. The figure of 30-35% is the average pregnancy rate at IVF-SYD.

When can I start treatment again if the test after frozen embryo treatment is negative?

You can begin new treatment immediately and don’t need to take a break.

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Fertilitetsklinik IVF-SYD
Skærbækvej 4
DK-7000 Fredericia

Tlf.: +45 76 24 50 20

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