In vitro fertilization (IVF) (in vitro means “in glass”) – technique of assisted reproductive technology. It is a process by which an egg is fertilized by sperm outside the body. The process involves a few stages such as: monitoring and stimulating a woman’s ovulatory process, removing eggs from the woman’s ovaries, letting sperm fertilize eggs in a liquid in a laboratory.
The fertilized egg is cultured for 2–6 days in a growth medium. After eggs are cultured they are implanted in another woman’s uterus, with the intention of establishing a successful pregnancy.
IVF technique is very popular in gestational surrogacy among gay couples. Male same sex couples often require a donated egg for IVF. In this case fertilized donor egg is implanted into a surrogate’s uterus, and the resulting child is genetically unrelated to the surrogate.
Louise Brown – first successful birth of a “test tube baby” occurred in 1978. She was born as a result of natural cycle IVF without stage of stimulation.
In 2010 Robert G. Edwards (physiologist who developed the treatment), was awarded the Nobel Prize in Physiology or Medicine. With egg donation and IVF all couples and singles who are in different situations because of which they can’t become parents can become parents.
There are five basic IVF stages:
Stage 1: Stimulation
In natural cycle a woman produces one egg per month. During the stimulation medicines are given to the woman to boost egg production and due to fertility drugs ovaries start to produce several eggs.
During stimulation, the woman will have regular examination (transvaginal ultrasounds) to examine the ovaries, make blood tests to check hormone levels and avoid problems with health.
Stage 2: Egg retrieval
A minor surgery (follicular aspiration) is done to remove the eggs from the ovaries.
The woman will be given medicines so she does not feel nothing during the procedure. Using ultrasound images a thin needle is inserted through the vagina into the ovary and sacs (follicles) containing the eggs. The needle is connected to a suction device, which pulls the eggs and fluid out of each follicle, one at a time.
Stage 3: Insemination and Fertilization
Insemination – mixing of the sperm and egg. The man’s sperm is placed together with the best quality eggs and are then stored in an environmentally controlled chamber. The sperm most often fertilizes an egg a few hours after insemination.
Intracytoplasmic sperm injection (ICSI) – direct sperm may injection into the egg in case of low chances of fertilization.
Stage 4: Embryo culture
When the fertilized egg divides, it becomes an embryo. Within about 5 days, a normal embryo has several cells that are actively dividing.
Pre-implantation genetic diagnosis (PGD) – removal of a single cell from each embryo and screening the material for specific genetic disorders in case of a high risk of passing a genetic disorder to a child. The procedure is done about 3 – 4 days after fertilization.
Stage 5: Embryo transfer
Embryos are placed into the woman’s womb 3 – 5 days after egg retrieval and fertilization.
The doctor inserts catheter containing the embryos into the woman’s vagina, through the cervix, and up into the womb. If an embryo sticks to the lining of the womb and grows, pregnancy happened.
Using IVF procedure there are high chances of multiple births. This is directly related to the practice of transferring multiple embryos at embryo transfer.
So, in some countries (e.g. Britain, Belgium) there are strict limits on the number of embryos that may be transferred to reduce the risk of high-order multiples (triplets or more), but are not universally followed or accepted.
Spontaneous splitting of embryos in the womb after transfer can occur, but this is rare and would lead to identical twins.