Frequently Asked Questions: “Why did my treatment fail?”
Once infertility treatment begins, it is normal for expectations to be high. Couples have often been hoping for a successful pregnancy for quite some time and finally something is being done to improve their likelihood for success. It is helpful to review some basic information concerning what can be referred to as “reproductive efficiency”. When couples with no reproductive problems stop using all contraceptive measures in the hopes of establishing a pregnancy, studies have shown that the prospects for achieving an ongoing pregnancy in any given month is about 20%. Stated another way, in spite of there being no known reproductive problems with a couple, pregnancy will fail to occur 80% of the time in any given single month. Large population based studies have documented this statistic.
The reasons for this reproductive inefficiency are not completely clear although it is well understood that men produce a significant number of genetically abnormal sperm cells, and women release a percentage of eggs that are genetically incapable of being fertilized. In addition, it is reasonable to assume that there may be other inefficiencies in the process of reproduction such as poor sperm migration due to variable conditions with the vagina, intra-pelvic anatomical conditions leading to failure of the egg to be picked up and transported by the fallopian tube, implantation failure due to nutritional or environmental effects on the uterine lining, or intermittent hormonal deficiencies leading to inadequate attachment of the embryo to the uterine wall.
For infertile couples, monthly fecundity (the likelihood of pregnancy occurring in any given month) is significantly reduced below the expected normal rate of 20%. For example, if a couple has never conceived in spite of trying for 29 months, the best possible fecundity this couple may achieve would be 33.3%. This number is arrived at by assuming that the couple achieved a pregnancy in their 30th month of trying. In this example, their own calculated monthly fecundity would be one pregnancy in 30 exposures, (1/30 or 3.3%). Comparing the expected normal monthly fecundity of 20% to this couple’s 3.3% (best case monthly fecundity) provides some framework for comparing expected outcomes with various commonly applied treatments. If we complete the infertility evaluation in this couple and conclude for example that their infertility is unexplained, we can use published data detailing the success of various treatments for management of unexplained infertility to provide them with their prospects for success. Again using the example above, if a given treatment is expected to achieve a monthly success rate (monthly fecundity) of 12-14% per cycle, it is clear that this particular treatment represents a substantial improvement in the couple’s prospects for pregnancy (3.3%, best case). With the exception of in-vitro-fertilization, which can result in monthly pregnancy rates up to 60-70% in young patients, most treatments cannot restore monthly fecundity to 20%. However, cumulative success rates over several months of treatment often surpass normal monthly fecundity of 20%.
In counseling couples following a failed treatment cycle, reviewing the fact that normal monthly fecundity is just 20%, reduces feelings of failure and provides logical and realistic hope for the future. It is helpful to remind patients that cumulative success rates over 2-3 months of treatment often surpass normal monthly fecundity of 20%.