In vitro fertilisation (IVF) is one of several assisted reproductive technologies (ART) used to help infertile couples to conceive a child. Approximately 20 per cent of couples experience fertility difficulties. (1.)
IVF is the process of fertilising eggs with sperm outside of the human body. Once the eggs are fertilised, the resulting embryos are placed in the woman’s uterus in the hope that a successful pregnancy will follow.
Success rates vary across IVF clinics and procedures, and with the woman’s age. Some clinics achieve pregnancies in about 90 per cent of women aged under 35 years, 85 percent of women aged 35 to 39, and 45 per cent of women aged 40 to 44. (1.)
How is PGD Performed
This process begins with a standard IVF cycle. For full details of this please go to the IVF section of the web site. Briefly, the ovaries are stimulated with medication. The eggs are harvested by ultrasound. Each egg is injected with a single sperm (ICSI). This is done to prevent the embryo from being covered with sperm DNA which can contaminate the embryo biopsy. The fertilized eggs (embryos) are then incubated for 3 days. Some embryos will naturally stop dividing. Others will be healthy and continue to divide. Healthy embryos which are at the 6 - 8 cell stage can then be biopsied. The biopsy technique involves removing carefully one cell and either fixing it to a slide or releasing its DNA for further analysis. The image below is of such a biopsy in progress.
Typically the biopsy is done by the IVF program and the genetic material is sent off to a genetic lab which is frequently in another city. The lab will then try to get results within the next 48 hours. If the results are available in that time frame, we have an opportunity to do a fresh embryo transfer usually 5 or 6 days after egg retrieval. If the results cannot be obtained within this time frame, the embryos can be frozen until the results are known. Then a frozen embryo transfer can be performed. Some programs will routinely biopsy at the blastocyst stage and freeze all the embryos. Transfer would later occur in a frozen cycle.
Stimulating the ovaries
Hormones are usually given to stimulate the ovaries to produce more than the usual one egg per cycle. This is to enable the collection of several eggs. The development of the eggs is monitored by blood tests and ultrasounds that ensure eggs are collected at precisely the right time.
Collecting the eggs
When the time comes to collect the eggs, an ultrasound probe is placed in the vagina while the woman is under light sedation. The ultrasound monitor shows where the follicles are within the ovaries.
A fine needle is passed through the vaginal wall and into the ovaries. Each follicle (sac of fluid) in the ovary is pierced in order to collect its egg.
Once the embryos have grown to a predetermined size, one or two will be transferred back to the woman’s uterus at the appropriate time in her menstrual cycle. This procedure involves passing a very fine plastic tube (catheter) through the cervix and into the uterine cavity under ultrasound guidance.
Embryo transfer is very similar to a pap test, is generally painless and usually involves no anaesthetic. Only one or two embryos are transferred at a time.
Two weeks after the transfer, blood is taken and tested to determine if the woman is pregnant.
Sex Selection: Can we choose the sex of our child?
Fertility specialists have the ability to create and identify embryos of either sex. However, it is illegal to choose baby's gender in the UK, unless there's a medical reason for it.
It’s illegal to choose baby's gender in the UK if you have a serious genetic condition that you risk passing on to your children. Only pre-implantation genetic diagnosis (PGD) has been approved as a technique which does this. So you can't medically intervene with conception just to balance your family, or for social or cultural reasons.
What would sex selection qualify?