Infertility, whether male or female, can be defined as "the inhability of a couple to achieve conception or to bring a pregnancy to term after a year or more of regular, unprotected intercourse".
8-10% of couples are infertile
The World Health Organization (WHO) estimates that approximately 8-10% of couples experience some form of infertility problem. On a worldwide scale, this means that 50-80 million people suffer from infertility. However, the incidence of infertility may vary from region to region. In France, 18% of couples in the childbearing age said that they had difficulties in conceiving.
Male infertility/female infertility
The incidence of infertility in men and women is very similar. Infertility is exclusively a female problem in 30-40% of the cases and exclusively a male problem in 10-30% of the cases. Problems common to both partners are diagnosed in 15-30% of infertile couples. After thorough medical investigations, the causes of the fertility problem remain unexplained in only a minority of infertile couples (5-10%).
- Tubal blockage and/or peritoneal factors account for approximately 35% of all female infertility problems.
- Irregular or abnormal ovulation accounts for approximately 25% of all female infertility cases.
- Endometriosis is found in about 35% of infertile women who have laparoscopy as part of their infertility work-up.
- Approximately 20% of couples who have a complete work-up are diagnosed with unexplained infertility because no specific cause is identified.
Normal fertile couples = 25% chance to conceive during each menstrual cycle
When talking about success rates for any type of infertility treatment, one should bear in mind that the average chance to conceive for a normal fertile couple having regular unprotected intercourses, is around 25% during each menstrual cycle. It is estimated that 10% of normal fertile couples fail to conceive within their first year of attempt and 5% after two years.
Effective treatment = up to 25% per cycle of treatment
Comparable to normal fertility rates, effective treatments can be expected to have on average up to a 25% success rate per cycle of treatment, and may therefore need to be repeated several times before a pregnancy is achieved. Simple ovulation induction to compensate for hormonal imbalances has a very high success rate; more than 80% of women suffering from such disorders are likely to conceive after several cycles of treatment with drugs such as clomiphene citrate or gonadotrophins.
Factors influencing the success of a treatment
In any type of infertility treatment, important factors need to be taken into account when referring to success rates. The age of the woman and the duration of the couple's infertility are likely to influence the success of treatment. In women, fecundity decreases as age increases, particularly after 40 years of age. When the woman is being treated, her chances of conceiving can be lessened if her partner also has infertility problems (e.g. poor quality sperm).
Success rates of IVF equal or superior to 25% in Europe
Overall, success rates for IVF have steadily improved over the last ten years. Birth rates for IVF vary according to the expertise of the centres practicing this technique. However, centres in Europe have reported pregnancy rates after one cycle of IVF equal or superior to 25%. In 1993, the French IVF registry (FIVNAT) reported a pregnancy rate of 25.4% per embryo transfer on a total of 23,025 oocytes retrieved. Based on such results, after three to four cycles of IVF, a woman under 40 whose partner does not have any fertility problems could reasonably expect to give birth.
Again, in general, success rates may vary from one centre to another, since they are influenced not only by the level of expertise of the medical team but also by the characteristics of the patients treated. A clinic treating a large number of women over 40 is likely to report lower success rates than a clinic having a majority of patients under 35.
Other techniques of assisted reproduction include gamete intrafallopian transfer (GIFT), zygote intrafallopian transfer (ZIFT), IVF with donor eggs, donor sperm, and donor embryos, and micromanipulation of eggs and embryos.
- According to the most recent statistics (1995), the success rates of ART procedures are as follows:
IVF - 22.3% live birth per egg retrieval
GIFT - 26.8% live birth per egg retrieval
ZIFT - 27.7% live birth per egg retrieval