Frequently Asked Questions
1. What sterilities or subfertilities require in vitro fertilization?
3. How does in vitro fertilization differ from in vivo fertilization?
4. Why do you stimulate the ovary before in vitro fertilization?
5. What conditions must be met for in vitro fertilization?
6. What technical conditions are essential for in vitro fertilization?
7. What laboratory procedures are needed for in vitro fertilization?
8. It is necessary to rest after embryo transfer?
9. What is the fate of embryos obtained by in vitro fertilization?
10. What are the conditions required for implantation of the embryo in the uterus?
1. What sterilities or subfertilities require in vitro fertilization?
Tubal sterilities, when they allow no chance of passage of either the ovule or spermatozoa (agenesis, complete obstruction, voluntary sterilization). Male subfertilities, when the number of competent spermatozoa (motile and morphologically of good quality) is too low to offer an acceptable chance of conception resulting from sexual intercourse. In these cases, in vitro fertilization is an adequate response because fewer spermatozoa are needed. In addition, in the cases of extremely severe subfertility, the chance of fertilization can be further enhanced in vitro by intra-oocyte insemination (ICSI). In vitro fertilization can sometimes, inexplicably, be effective in cases of unexplained infertilities of long duration.
2. Is it true that spontaneous fertilization can occur in certain couples enrolled in an in vitro fertilization program?
Yes. Around 5% of the couples enrolled in an in vitro fertilization program obtain a pregnancy before the onset of any treatment and 17% after treatment with assisted reproduction techniques (ART), regardless of whether the latter end in success or failure. Conception is observed only in subfertile couples, who have not used their last chance of pregnancy before treatment. However, this success does not mean that no attempt should have been made to help them. Their chances of reproducing spontaneously are, in all cases, much lower in a spontaneous cycle (without treatment, during sexual intercourse) than during in vitro fertilization (around 1 chance out of 2 after 3 attempts). In vitro fertilization does not resolve the couple's problem(s) of infertility. In vitro fertilization can shorten the time for the desire to have a child to become a reality. Other than some particular cases, like the absence of gametes, the chances of pregnancy over time are unique to each couple, without ever being completely null.
3. How does in vitro fertilization differ from in vivo fertilization?
Fertilization in vitro (in a tube) enables or improves the probability of the encounter between the ovule and the spermatozoon. In vivo (in the body), this encounter takes place in the Fallopian tube. Indeed, in vitro fertilization was devised to circumvent problems posed by tubal obstruction. Its range was later extended to other causes of subfertility in women and to problems of male subfertility, shedding light on the performance of spermatozoa. During in vitro fertilization, only the stages of fertilization and the very first cell divisions take place outside the woman's body.
4. Why do you stimulate the ovary before in vitro fertilization?
During the course of a natural or spontaneous cycle, usually only one oocyte matures completely with the 'intention' of being fertilized. Thus, only a single embryo can be obtained. Only half of the embryos obtained either spontaneously or after in vitro fertilization are capable of developing and terminating in the birth of a child. The rate of early miscarriages observed in the general population is very clearly underestimated for the simple reason that many of them occur before the delayed onset of menstrual bleeding, that is, before the woman suspects a possible pregnancy. Ovarian stimulation is used to induce the maturation of multiple oocytes that can be retrieved for the preparation of several embryos, in order to increase the chance of transferring into the uterus a viable embryo apt to develop. It is one of the ways that in vitro fertilization shortens the time for the desire to have a child to become a reality. Ovarian stimulation consists of the administration of a hormone, called follicle-stimulating hormone (FSH), that is the same as the one that naturally provokes the spontaneous maturation of a single follicle enveloping an oocyte.
5. What conditions must be met for in vitro fertilization?
Spermatozoa and oocytes (ovules or eggs) must be available. Most of the time, spermatozoa are isolated from the ejaculate obtained by masturbation. In certain cases, notably when an obstacle blocks the male genital system, it is possible to retrieve spermatozoa by puncture of the deferent canal, the epididymis or even the testicle. The oocytes are extracted from the follicular fluid obtained by ultrasonography-guided aspiration of follicles within the ovary.
6. What technical conditions are essential for in vitro fertilization?
In vitro fertilization has been a routine procedure only since the early 1980s, when artificial media imitating the natural conditions found in the Fallopian tube were perfected and thus could assure the survival of spermatozoa and oocytes, enabling fertilization and embryo development through its first stages. The composition of this medium and the culture conditions (the supply of mineral salts, oxygen and organic molecules, antibiotics, temperature, acidity, osmolarity) are rigorously defined and calculated based on the natural environment found in the Fallopian tube.
7. What laboratory procedures are needed for in vitro fertilization?
The various steps are conducted in the laboratory over a period of 3 to 7 days. They are: the preparation of spermatozoa for insemination; the localization of oocytes, putting them in culture and preparing the ovules for insemination; insemination of the culture; observation of the embryos for a variable period; preparation of embryos in the laboratory for transfer into the uterus by the gynecologist; and the cryopreservation of embryos to be transferred at a later date.
8. Is it necessary to rest after embryo transfer?
No. Your embryos have now returned to their natural environment, where they would be had fertilization been achieved spontaneously. Thus, you can lead a completely normal life, just like any woman who still doesn't know that she has conceived and will soon be pregnant.
9. What is the fate of embryos obtained by in vitro fertilization?
The main rule is that all embryos are obtained with the objective of being transferred, immediately or after cryopreservation, into the uterus of a woman where they will pursue a 'normal' course, leading to implantation in the uterine mucosa or not. If at the end of the cryopreservation term (5 years) the couple has not requested their thawing for a new transfer, we ask them to decide what should be done with their frozen embryos: donated to science or another couple, or destroyed.
10. What are the conditions required for implantation of the embryo in the uterus?
It is essential that the embryo be viable. Many embryos obtained naturally or artificially in the laboratory have genetic characteristics that prevent their development and implantation. It is also essential that the uterine mucosa be adequate (referred to as receptive) for implantation. Precise characteristics, in terms of hormonal environment and other physiological parameters, are also required to receive the embryo.
