Many people we see at Sher St. Louis think of infertility in terms of childlessness. But in almost half of infertility cases, problems conceiving may not manifest until after the birth of a first (second, third) child. In other cases, a couple may have a child with the aid of Assisted Reproductive Technology, but wish to have another. The inability to have a child after the prior birth of another child is referred to as “Secondary Infertility”.
Let’s take a look at some of the factors that can cause a seemingly fertile individual or couple to “suddenly” become infertile.
With advancing age, a woman’s eggs diminish in quality. What this means is that regardless of the quantity of eggs present in her ovaries, the number of chromosomally “normal” eggs declines rapidly with age. For example, at age 28, approximately 1 in 2 eggs are chromosomally normal (meaning they have the correct number of chromosomes). We call these eggs “euploid.” At age 36, only about 1 in 5 eggs is euploid. By age 42, only about 1 in 10 eggs is chromosomally intact. Eggs with more or less than the correct number of chromosomes are referred to as “aneuploid” eggs. Aneuploid eggs cannot make a healthy baby. When an abnormal egg is penetrated by a sperm cell, the outcome can be one of the following scenarios:
- The egg will fail to fertilize
- The egg will fertilize, then begin to develop abnormally, ending in a miscarriage
- The egg will fertilize and develop into a baby with a chromosomal abnormality such as Down Syndrome.
The human immune system is an amazingly complex machine. Normally, when a foreign object is introduced into the body’s systems, it is fought off and rejected by the immune system. The one exception to this rule is an embryo. Since the embryo is composed of 50% foreign material (the Father’s genetic contribution), we would assume that the immune system would reject the embryo. However, this is the paradox of conception. In the case of an embryo, the immune system EXPECTS the embryo to be UNLIKE the mother’s composition. When, in rare instances, the male and female partner share certain specific genetic factors (DQ-Alpha match), the woman’s immune system actually rejects the embryo for being too similar. This is known as Alloimmune Implantation Dysfunction (find detailed information on this condition HERE). Because immunologic implantation dysfunction only manifests when the woman’s natural killer cells become “activated” (which can occur during or after a pregnancy), it is possible for a couple to conceive easily the first time, and experience this phenomenon in ensuing attempts.
If a woman has conceived with a prior partner, but is experiencing difficulty conceiving with her current partner, the obvious starting point is male factor testing on the new partner. If tests are within normal limits, the woman should consult with a fertility specialist and undergo basic testing to identify any potential issues that may have developed since her last pregnancy. Finally, the above-mentioned Alloimmune Implantation Dysfunction should be considered and tested.
It is quite common for women with Endometriosis to experience secondary infertility. Over time, the endometriosis prompts the evolution of a toxic (to the embryo) pelvic environment. As the woman’s age progresses, she may be unable to conceive because of this. Secondary infertility is quite often a partial result of endometriosis.
For a more detailed analysis of the factors that contribute to secondary infertility, please click on this article, or schedule an appointment with Sher Fertility St. Louis.