The IVF Journey: Test Tube Baby

Q1. What is IVF? What is the success rate?

In vitro fertilisation (IVF)refers to fertilisation in a laboratory outside a body. In a laboratory setting, the eggs are fertilised by a man’s sperm outside the body, develops into an embryo and are transferred back into the uterine cavity. The baby thus conceived is also known as a “Test Tube Baby”.

In natural conception, the chance of pregnancy each month is about 10 to 15%. A total of 10 to 15 eggs are usually retrieved in each IVF cycle for selection, and those which are abnormal, unfertilised or fail to divide as a normal embryo are discarded.  The chance of pregnancy increases as we have better selection, and only embryos that survive and normally divide are selected.

Q2. What are the procedures of IVF? Who are suitable?

A cycle of IVF involves five steps. It begins with ovarian stimulation with hormone injection, which typically starts on day 2 or 3 of the menstrual cycle to stimulate the ovaries to produce multiple eggs. The injections are usually given for 8 to 10 days with the aim of developing more than 10 eggs. The second step is egg retrieval, in which a needle is inserted to remove the eggs through vagina under anaesthesia and ultrasound guidance. In the embryology laboratory, the retrieved eggs are fertilised with the husband’s sperm. The resulting embryos will be cultured in the laboratory for 2 to 5 days, only those that divide normally will be selected for transfer or frozen for later use. Finally, the selected embryo(s) is/are transferred back into the uterine cavity for implantation.

IVF helps couples who are subfertile with various causes; like for patients with ovulation disorder or poor ovarian reserve, as more eggs are developed and available for selection with ovarian stimulation.  In addition, as the eggs are retrieved vaginally, it helps to bypass any pelvic-peritoneal or fallopian tube factors.  Moreover, by placing the eggs and sperm in close proximity in the culture medium or even by injecting a single sperm directly into the egg when necessary, it helps to facilitate fertilisation especially for patients with male factor or fertilisation problem.  As the embryos can be selected, not only people with infertility but those with recurrent miscarriage or in need of embryo testing, e.g. couples with hereditary disease, can choose to undergo preimplantation genetic screening.

Q3. What is PGT?

PGT, i.e. preimplantation genetic testing (PGT) is a genetic test done on an embryo before the embryo is selected for transfer. During IVF, the embryos are cultured for 5 to 6 days until the blastocyst stage. A few cells are then extracted from the outer layer (trophectoderm) for DNA testing to check if there is any abnormality in the number of chromosomes or monogenic diseases.

Q4. Who should consider PGT? How can PGT help?

There are 3 types of PGT, namely PGT-A, PGT-M and PGT-SR. PGT-A is performed to check for any abnormality in the number of chromosomes, i.e. aneuploidy. It is suitable for women with recurrent miscarriage, recurrent implantation failure or at advanced maternal age, given they are at higher risk of having embryos with numerical abnormalities of chromosomes such as Down syndrome. PGT-A helps to reduce the chance of failed pregnancy or miscarriage caused by numerical chromosomal abnormalities.

PGT-M tests for monogenic diseases, and is usually performed for couples with monogenic or single gene disorders, the most common of which is Thalassemia. If both partners are thalassemia carriers, the chance of their baby suffering from Thalassemia major is 25%. Genetic testing can be performed before embryo transfer to reduce the risk.

The third type is Structural Rearrangement (SR). Couples of balanced chromosomal rearrangements (BCRs) are at increased risk of producing offspring with chromosomal abnormality for hereditary reasons. The chance of failed pregnancy or miscarriage can be reduced if the embryos are checked prior to transfer.

Q5. Is IVF painful?

With fine needles, injections for ovarian stimulation are usually given subcutaneously into the abdomen for 8 to 10 days. The injections are similar to insulin injections and do not cause too much discomfort. The pain is largely reduced or eliminated during egg retrieval as it is carried out under anaesthesia.

Q6. Can IVF prevent ectopic pregnancy?

Although the embryo is transferred into the uterine cavity, the risk of ectopic pregnancy still exists. There is still a chance that the embryo is expelled due to uterine contraction. The risk of ectopic pregnancy increases in patients with fallopian tube problems, inflammation or a history of surgery. Therefore, the implantation site must be checked by doctors even in an IVF pregnancy.