In vitro fertilization, or IVF, is the process of fertilizing ova (egg cells) with sperm outside the body in a laboratory setting. IVF is a major tool for reproductive assistance.
To perform IVF, both eggs and sperm must be collected. In most instances, the female partner is treated with hormones to cause her to ovulate multiple eggs on a predetermined schedule. The eggs are collected via microsurgery and placed into a nutrient solution. Sperm is collected, usually by standard ejaculation, and the sperm is added to the eggs. Between 48 and 72 hours later, fertilized eggs will have formed into embryos of 4 to 8 cells. The embryos can be transferred at this point, or can be held until they have developed to the blastocyst stage before transfer (different IVF clinics have different protocols). One or more embryos are placed into the uterus via a thin, flexible tube called a uterine catheter.
Ethical issues abound regarding this technology. Some people feel that it is "playing God" and is therefore an inappropriate way to make a baby.
Those who feel strongly about the dangers of human overpopulation of the planet object to using technology to create more new lives.
In most IVF clinics, multiple embryos are implanted to increase the likelihood of successful implantation with the idea that, should too many embryos survive, the pregnancy can be "reduced" by selective abortion of some of the fetuses. This is done to protect the health of the mother and the remaining babies, but it creates a serious ethical dilemma.
Last, IVF is very expensive, and is consequently available to only a portion of the population, raising the ethical question of whether money should be a deciding factor in who gets to become a parent.
It may also be helpful to understand the process of natural conception. Think about your IVF cycle as natural conception process aided by our fertility specialists. Human conception is a relatively simple and yet amazingly complex process.
The process begins on the first day of your menstrual cycle. We also call this day Cycle Day 1. During the next 12 to 14 days occurs what fertility specialists call follicular phase, the event that results in the ovulation of a mature egg. It’s called "follicular phase," because the eggs develop in a fluid-filled sacs called the follicles. On Cycle Day 1, your body starts developing follicles. Many eggs begin to develop during each monthly cycle. Naturally, however, usually just one of the eggs will reach maturity while the rest undergo a process known as atresia, or degeneration, and are lost forever. When that one egg is mature, it is released from the ovary. With IVF medications, fertility doctors help your body to develop more than one egg during the first 10 days of the cycle. The egg will be capable of being fertilized for only the next 12 to 24 hours. If not fertilized within that time, it is simply reabsorbed by the body.
On day 14 of the typical 28-day cycle, woman’s egg is mature and ovulation occurs. As the egg begins it descend through the fallopian tubes, it meets with sperm and gets fertilized. Ovulation triggers many other changes in the body. The cervical mucus becomes penetrable, and the lining of the uterus is getting ready to accept an implantation. In contract to the natural process, our IVF doctors will retrieve the mature eggs on Cycle Day 12. Normally IVF medications are taken for 10 days. However, if patient’s ovaries don’t respond well, you may be instructed to take medication up to five days longer.
Typically, IVF clinics perform egg retrieval on Cycle Day 12. The very same day, the eggs are fertilized with sperm either by conventional insemination or by Intracytoplasmic Sperm Injection (ICSI). The eggs will be checked the following day to document fertilization and again the next day to evaluate for early cell division. Until recently, embryos were cultured for three days and then transferred to the uterus and/or cryogenically frozen for later use. As mentioned in the previous comment, IVF clinics now have the ability to grow the embryos for five or six days until they reach the blastocyst stage. Blastocysts are believed to have a greater chance of implantation. This, in turn, allows our IVF doctors to transfer fewer embryos and lower the risk of multiple births while increasing the chance of pregnancy. Recently, however, I have been hearing about the trend of transferring embryos three days after fertilization.
The final step in the IVF cycle is the embryo transfer. As it is the case with the natural fertilization, not all embryos will grow in the laboratory dish. The embryo(s) that continue to divide and grow is transferred into recipient’s uterus about the time it would arrive there in a natural conception. Unused embryos can be cryopreserved for later use.