Understanding Assisted Reproductive Technologies: In Vitro Fertilization (IVF)
In vitro fertilization (IVF) is an assisted reproductive technology (ART) in which a woman’s eggs and a man’s sperms are retrieved and then manually combined for fertilization in a petri-dish in a laboratory. The resulting embryo is then transferred to the uterus.
When is IVF used?
IVF treatment is usually suggested when other less invasive ARTs, like ovulation induction and intrauterine insemination, have failed. It can be used as an alternative for the below conditions:
- Fallopian tube blockage or damage/ Absent tubes: This makes it difficult for the egg to get fertilized or for the embryo to travel to the uterus.
- Ovulation disorders: The total number of eggs available for fertilization are impacted by irregular ovulation or its absence.
- Advanced Reproductive age: Where time is of the essence and chance of conceiving naturally are lower.
- Endometriosis: This leads to uterine tissue developing outside the womb and can adversely impact the function of uterus, ovaries and fallopian tubes.
- Uterine fibroids: These are small, benign tumors on the walls of the uterus, which affects the ability of the fertilized egg to get implanted on the uterus lining.
- Genetic disorders: Couples who are at risk of passing on genetic disorders (are carriers) to the child have the option of opting for preimplantation genetic testing – which involves getting pregnant through IVF. After the eggs and sperms are harvested and the egg fertilized, the embryo can be screened for any genetic abnormalities, and the ones which are normal can be transferred to the uterus.
- Male factor infertility: Where the partner has low sperm count or fewer motile sperms and sperms need to be extracted from the testicles.
- Unexplained infertility: At times, there is no obvious cause of infertility, and in such cases IVF is recommended.
How is IVF done?
The couple is educated about the complexity involved in undergoing IVF, its advantages and risks as well as techniques for taking injections at home. From the time the procedure starts, the doctor will monitor the woman’s ovaries till the IVF is successful to ensure that the eggs are released and fertilized at the right time.
- Fertility medications are provided to stimulate the ovaries to produce multiple follicles, each follicle contains an egg. This is because some eggs will not fertilize after retrieval.
- Eggs are retrieved through a surgical procedure where a thin needle is inserted through the upper vaginal walls and the fluid containing the eggs is retrieved from the follicles of the ovaries. Light pain medication is provided to ease the discomfort and pain.
- A sperm sample is secured and added to the eggs retrieved. To increase the chances of fertilization, at times the doctor will directly inject one sperm into the egg using a micro-needle and a microscope. This is called intracytoplasmic sperm injection (ICSI), and is an option for men with severe male factor infertility, regardless of their sperm count. Fertilization rates with ICSI range from 50-70%. The doctor monitors the egg fertilization to ensure that healthy embryos are developed.
- After three to five days post fertilization, the embryos are transferred into the woman’s uterus through a small tube placed through the cervix into the uterine cavity. If successful, the implantation happens six to eight days after the procedure.
How many embryos are transferred?
The number of embryos transferred depends on the woman’s age, preference, quality of eggs and history of pregnancy and miscarriages. Women under the age of 35 years are often advised to have only one embryo transferred during IVF. If, even after multiple attempts, IVF is unsuccessful, then the doctor could advise transferring more than one or two embryos to increase the chances of getting pregnant. However, this could also increase the risks of getting multiple pregnancies. For women over the age of 40 years, up to five embryos could be transferred due to lower rates of implantation. For older women receiving eggs from a younger donor, the rate of implantation is similar to a younger woman and hence no more than one or two embryos are transferred.
What happens to unused embryos?
Embryos which are not used for transfer may be stored by freezing them at sub-zero temperatures, also called cryopreservation. Both fresh and frozen embryos have equal chances of success. While the embryos could be frozen for a very long time, it is advised for couples to eventually chose among the following options:
- Transfer the embryos at some point in future
- Donate them for use by another couple or for research
- Dispose off the embryos
Advantages of IVF
- IVF helps couples in having a baby who otherwise would not have been able to conceive naturally. It also maximises the chances of conception for older couples or women who have low ovarian reserve.
- IVF is more successful than other forms of ARTs. For a woman under that age of 35, the success rate is about 40%, whereas for a woman over 40 years of age the success rate dips to 10%. The success rates have increased through the years due to advances in technology.
- It can help single women and same-sex couple to have a baby through sperm/egg donation.
- IVF can also help diagnose fertilisation problems, which otherwise would not have been detected by other ARTs.
- The embryos formed through IVF can be screened for genetic disorders or chromosomal abnormalities and hence minimise the risk of miscarriages or birth disorders.
Disadvantages of IVF
- An IVF cycle is not necessarily always successful. Couples might need to go through multiple cycles before getting successfully pregnant. An individual’s chance of success depends on several factors, including the woman’s age, cause of infertility, and treatment approach.
- There could be side effects to the treatment, the most severe case being ovarian hyper-stimulation syndrome (OHSS). It could lead to severe abdominal pain, nausea and if left untreated, fluid imbalances in the blood and blood clots in legs or lungs. About 2-6% of the women undergoing IVF get mild symptoms of OHSS. Severe OHSS occurs in about 1% of women, typically when more than 20 eggs are retrieved. However, with little to no drug usage for IVF treatment, the risk of OHSS could be reduced.
- There is a possibility of more than one embryo being transferred to the uterus, which can lead to multiple pregnancies. Multiple pregnancies are associated with an increased risk of premature labour, caesarean operation, miscarriage, stillbirth and health problems for the mother and the child.
- IVF treatment is expensive, and it could take a financial, emotional and psychological toll on the couples going through multiple cycles.