Having the Bonus of Frozen Embryos

The techniques for freezing eggs haven't yet been perfected (see Chapter 15) but scientists have developed very successful methods for freezing and thawing embryos (see Chapter 7). After a stimulated cycle, extra embryos are sometimes available that the embryologist judges as good quality and these embryos can be frozen for later transfers. Depending on how many embryos you have, these extra frozen embryos give you bonus chances of getting pregnant without having to go through all the hormone injections again!

Embryos can be kept frozen for many years, so if you fall pregnant after a stimulated cycle you can use your frozen embryos to have a second (or third or fourth . . .) baby if you want. If you don't fall pregnant after the stimulated cycle, you can use your frozen embryos as soon as you're ready. Some lucky couples complete their family with a single 'batch' of embryos: One clinic website mentions a couple who've had four children, one at a time, from the one stimulated cycle.

One of the critical parts of a frozen embryo transfer cycle is getting the transfer timing right. To maximise the chance of an embryo implanting, it needs to be transferred when the lining in the uterus is just right for implantation.

1 If you have a regular menstrual cycle, the clinic monitors your cycle to determine when you ovulate, because just after ovulation is the right time to transfer the embryo. So, to use a frozen embryo, you contact the clinic on the first day of your period and the nurses tell you when to start monitoring ovulation, which in most clinics involves the following:

• A few days before ovulation is expected you have an ultrasound examination to check the size of the largest follicle and measure the thickness of the lining in the uterus, which are clues to when you're likely to ovulate.

• When you're close to ovulation you also have either daily blood or urine tests to detect the surge of luteinising hormone, which happens about a day before ovulation.

• Embryo transfer is scheduled three to five days after this luteinising hormone surge, depending on the stage at which the embryos were frozen.

1 If you have an irregular menstrual cycle and it's difficult to know if or when you ovulate, you need to either complete an artificial cycle or have some hormone stimulation to make you ovulate. Both these methods aim to make the lining in your uterus suitable for implantation.

To complete an artificial cycle, you take medication to mimic the hormones produced by the ovaries in a normal menstrual cycle:

• You start by taking oestrogen tablets, which help grow the uterine lining.

• Ten to 14 days later you have an ultrasound examination to measure the thickness of the lining in your uterus.

• When the lining reaches a certain thickness (in most clinics this means 8 mm or more), you take progesterone in the form of injections, vaginal gel or pessaries.

• Embryo transfer is scheduled a few days after you start the progesterone.

• You must keep taking oestrogen and progesterone until the day of your pregnancy test and continue until week ten of the pregnancy if you're pregnant.

To help you to ovulate in preparation for transfer of frozen embryos your doctor:

• Prescribes a course of clomid tablets or FSH injections (see Chapter 6)

• Monitors follicle growth via ultrasound

• Asks you to have daily blood or urine tests when you're close to ovulating until the tests show a surge of luteinising hormone, which happens about one day before ovulation

• Schedules embryo transfer three to five days after this surge of luteinising hormone, depending on the stage at which your embryos were frozen tSER

In a natural cycle, you may get a period before you have your pregnancy test if the treatment hasn't worked. This is because the progesterone level drops if the embryo doesn't implant — which triggers the period to start. But in an artificial cycle you continue to take progesterone until the day of your pregnancy test, so the level doesn't drop and the period isn't triggered if the embryo hasn't implanted. As a result, if you've completed an artificial cycle you need to keep your cool and wait for the results of your pregnancy test before getting too hopeful. Even if your period doesn't start before the pregnancy test, the treatment may not have worked.

Report immediately to the nurses any bleeding you have, because bleeding may indicate that your progesterone levels are too low and need to be topped up with additional progesterone pessaries, gel or injections.

Pregnancy Guide

Pregnancy Guide

A Beginner's Guide to Healthy Pregnancy. If you suspect, or know, that you are pregnant, we ho pe you have already visited your doctor. Presuming that you have confirmed your suspicions and that this is your first child, or that you wish to take better care of yourself d uring pregnancy than you did during your other pregnancies; you have come to the right place.

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