Possible Causes of Failed Implantation/Pregnancy Loss
There is no question that a failed pregnancy test or pregnancy loss are traumatic, devastating events. It’s important to grieve these losses and seek professional help from a grief counselor if needed.
There are many possible causes of failed implantation or pregnancy loss, though sometimes the exact cause is unknown. In general, a successful pregnancy relies on a good quality embryo implanting into an optimal uterine environment and developing under the right bodily conditions. Here we will discuss some possible causes of failed implantation or pregnancy loss:
Embryonic causes:
Embryos that do not develop properly are less likely to implant. They are also more likely to have genetic abnormalities that prevent them from implanting or developing properly following implantation.
With IVF, embryos that are poor quality or slow in development are less likely to implant and more likely to stop developing following an embryo transfer versus good quality embryos that develop at a normal rate in the IVF lab.
Uterine causes:
The uterine lining (endometrium) is not thick enough for optimal embryo implantation and development
There is too much bad bacteria or not enough good bacteria present in the uterus
The uterus contains abnormalities such as polyps, fibroids, or adhesions (scar tissue) that interfere with implantation and development
Congenital uterine abnormalities such as a septate, unicornuate, and bicornuate uterus.
Hydrosalpinx (fluid from the fallopian tubes leaks into the uterus)
The presence of too many uterine natural killer (NK) cells, which can affect implantation of the placenta
Systemic causes:
Thyroid problems, which can alter reproductive hormone levels and affect embryo implantation and development
Autoimmune diseases, such as thrombolytic antiphospholipid syndrome (APS, where abnormal blood clotting affects normal embryo implantation and development) and Lupus
Alloimmune causes (when the embryo and the uterus are “too genetically similar” and the carrier’s body rejects the embryo)
Endometriosis
In many cases, there are ways to treat these causes. For example, medications to thicken the uterine lining or balance thyroid hormone levels can improve pregnancy outcomes.
