It is humbling to put in perspective that even among fertile couples with no issues getting pregnant, estimates range from a 10 to 20 percent chance of achieving pregnancy any given month they try. In other words, fertile couples are unsuccessful 80 to 90 percent of the time. This is what we see when we look at the success of thousands of young couples who start the journey to build their family. Most will achieve pregnancy within the first year of trying; for others, there are treatments now available to help almost everyone conceive.
How common is unexplained infertility?
When couples come to an infertility specialist, they want answers. We proceed through the diagnostic testing process to identify a cause for their inability to achieve pregnancy. In about 10% of the time, a young couple (woman’s age less than 35 years old) will get an inconclusive result: Unexplained infertility. It is important to understand what this really means. The diagnostic testing we have available will only identify the major reasons why a couple may have a difficult time getting pregnant but it certainly cannot identify all the reasons. If the Fallopian tubes are blocked or there is no sperm, these are obvious major obstacles to becoming pregnant, and can be identified through diagnostic testing. There are, however, no 100% definitive tests available for more subtle infertility factors such as poor egg quality and fertilization failure.
Among couples with unexplained infertility we also know that despite all the normal diagnostic testing, they only achieve a pregnancy 1 to 4% any given month of trying without fertility treatment—much lower chances than 10 to 20%. This is why ultimately many couples choose in vitro fertilization (IVF) to attain their family building goals. In fact, a large randomized trial on couples with unexplained infertility called FASTT showed definitively that couples unsuccessful after three cycles of Clomid and intrauterine insemination (IUI) should proceed to IVF as their next treatment because they will more likely become pregnant, achieve their baby sooner, and will spend less money overall in fertility treatment.
Often the subtle infertility factors of unexplained infertility can be seen during IVF, so IVF can also be diagnostic. Even women with excellent ovarian reserve can have poor egg quality seen under the microscope at the time of egg retrieval. Couples with mature eggs and normal semen parameters may have poor fertilization, which can only be seen during IVF. Sometimes embryo development is the issue. Sometimes it’s an implantation issue. These are the diagnostic benefits of IVF that cannot be detected in any other way. In addition, once identified there are many options for treating and overcoming these infertility factors with IVF.
Although IVF does not fix all infertility factors, it is still the most successful treatment option for most couples and affords many bonuses. The risk of multiple gestation (twins, triplets, etc.) can be controlled with the number of embryos that are placed back in the woman’s uterus. The woman’s fertility can also be preserved by creating surplus embryos that can be frozen at her current age and transferred later when she is ready for baby 2 or 3.
Written by: Kara Nguyen, M.D., M.P.H, of Shady Grove Fertility’s Reading, PA and Harrisburg, PA offices.
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