In Vitro Fertilization
What is "in vitro fertilization" or "IVF"?
In vitro fertilization, abbreviated to IVF, is simply where fertilization takes place in vitro, which means in the laboratory. Using this form of assistive reproductive techonology, the first kind of "test tube baby" was born. During the IVF process, the eggs are collected from the woman and combined with sperm in the laboratory. After fertilization takes place, the embryos are allowed to grow for a few days and then placed back into the body of the woman. So, IVF typically involves the collection of multiple eggs because they stimulate the ovaries, although not a necessary part of the process, and then fertilization in the laboratory normally happens as a result of the sperm simply being combined with the egg. Although again you could use ICSI, Intra-Cytoplasmic Sperm Injection, to achieve fertilization if the sperm are unable to do it in the usual way, and the embryos are typically grown for about three, four, or perhaps five days and then put back inside the uterus. This is the basic assistive reproductive technology upon which all of the others are based.
What are "oocytes" or "eggs"?
The fertility equation consists of eggs and sperm coming together to make an embryo, the embryo then implanting, and after implantation producing a fetus. So the most important part of this equation is the egg. Even though fifty percent of the genes come from the mother and fifty percent of the genes come from the father, in the dance of fertilization, or in the dance of love that results in the production of a fetus, the egg is by far and away more important primarily because it is so much bigger than the sperm. So the term "oocyte" is used for the egg (that's the Latin form of the word) and oocytes, or eggs, grow incide the follicles, which are grape-like structures on the surface of the ovary, and they mature there prior to being ovulated and being picked up by the end of the fallopian tube. So the development of eggs in the ovary also makes it possible for us to do IVF (In Vitro Fertilization) because it turns out that for about two hours or so prior to the time of normal ovulation, the egg can be retrieved from the ovary by placing a hollow needle through the wall of the follicle and sucking out the liquid that is in the follicle, and thereby getting the egg into the laboratory, and then being able to go on and fertilize it. But the egg is the most important player in this game.
How long does it normally take to become pregnant using in vitro fertilization?
In vitro fertilization success rates have increased dramatically in the 29 years that this technology has been around. In the early days, I would say all the way up into the mid 1980s, success rates really were less than 2 percent. So it was harder to get pregnant with IVF than it would have been for a normally fertile couple, to get the probability of getting pregnant in any one month. But as time has gone by we can now get statistics stating about 5 percent success rates in young women under the age of 35. So a young couple who decides to go for IVF has about a 50/50 chance of getting pregnant in any one cycle of IVF. When someone asks me how long does it take to get pregnant with IVF, I would say on average about one month. About half the time the process is successful the first time round.
What factors can affect the success of in vitro fertilization?
IVF depends on the successful retrieval of eggs, on their successful combination with sperm, and the successful implantation of the resulting embryo. Things can go wrong anywhere along the way. It turns out that most of the time we can get eggs from the woman, most of the time we can get sperm from the man, and most of the time we can get fertilization, especially now with the use of introcytoplasmic sperm injection, which allows fertilization to occur, even for men whose sperm are not very good swimmers or not very good at achieving fertilization. The trick with IVF is to get the resulting embryo to implant in the uterus, and this depends on both the egg quality and the strength of the embryo that results from that egg, as well as on the uterus. We want to make sure that the uterine cavity is normal and the uterine lining has been properly prepared. So if you want to think of it as the seed and the soil, you need both a good seed - that is to say, a good embryo - and you need the good soil, the good preparation of the uterine lining, or the endometrium, to make sure that the embryo implants and then goes on to produce the fetus later on after implantation has occured.
How are my eggs collected for in vitro fertilization?
To get eggs out of the ovary, you first have to get to the ovary. So, the first method that was used to do this was laparoscopy. Laparoscopy was brand new in the 1970's and was thought to be a much less traumatic way of getting into the abdomen (which is where the ovaries are located) than actually open the abdomen up with a laparotomy incision. Imagine if we have to make an incision in the abdomen every time we were trying to get eggs out; that will be very difficult. So, laparoscopy was used first by the late 1980's about 20 years ago. Ultrasound technology is getting much better and we were able to visualize the ovary and visualize the follicles by the use of this non invasive technology. So, now virtually every egg retrieval procedure in the world that takes place is done under ultrasound guidance. The simplest way to do this is to use transvaginal ultrasound probe which is used to visualise the ovary and then attached to that probe is a needle guide. The needle then can be guided under direct ultrasound visualisation into the follicle and the follicular fluid, and the egg can be retrieved. When transvaginal ultrasound guided follicle aspiration for egg retrieval was first developed (which was done in Europe), they did not use any anaesthesia for this because the discomfort was thought to be fairly mild. However, of course this is long gone; we use local anaesthesia for dental procedures and we also use anaesthesia or at least some type of a sedation for the egg retrieval process, so its quiet painless and the patient does not feel anything.
What are the benefits and disadvantages of using my own eggs for in vitro fertilization?
Most couples of course want to have their own biological child. Most couples really would ideally like to not have any infertility in the first place; but if they have to go to the doctor's office of course what they want is they want to use the wife's eggs and the man's sperm to produce their own biological child. In some cases this is not possible. It is very rare now that we have to use a sperm donor in association with assisted reproductive technologies because of the intracytoplasmic sperm injection technique that makes it possible for men who have very weak sperm to achieve fertilisation. However, the egg is such an important player in the game that women over the age of 40 or women who are approaching menopause (even at other ages) may have eggs that are not good enough to be able to produce an embryo that will actually implant, and these women end up having to use a donor egg. It's very easy to say that the donor egg is a more successful technology; of course it's easier to achieve fertilisation if you take egg from a young fertile egg donor. However, most couples would prefer to get pregnant with their own genetic material, and so of course in the vast majority of couples we begin by using the wife's own eggs and the husband's sperm in order to help them become pregnant and resort to donor egg or to donor sperm only as a last resort.
What are the benefits and disadvantages of using frozen eggs for in vitro fertilization?
The use of frozen eggs is relatively new. The technology of egg freezing actually dates back to 1986, but the technology was very unsuccessful, and perhaps only one percent of frozen eggs ever became babies. It is only recently that the technology has gotten to the point where success rates really are similar to those of frozen embryos. The advantage of using a frozen egg over using the woman's own egg is that that frozen egg may come from a time when she was younger. So, if a woman freezes her egg at the age of thirty, and comes back and wants to use it now at the age of forty-five, then of course, that frozen egg is only thirty years old. It has been in suspended animation for the last fifteen years, whereas her own eggs have aged a very important fifteen years in between to the point where they are very unlikely to produce a baby at this point. However, under most circumstances, you would rather use a fresh egg rather than a frozen one because the freezing does take some of the strength out of the egg. There is no question that pregnancy with a fresh egg is more likely to occur than with the use of a frozen egg.