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Recurrent implantation failure (RIF) is only related to patients undergoing assisted reproductive technologies (ART) treatment. It is defined as three or more in vitro fertilization (IVF) – embryo transfer failures. Recurrent pregnancy loss (RPL) is defined as three or more pregnancy losses.
Maternal age is an important factor responsible for the quality of embryos. Also, the risk of aneuploidy (abnormal number of chromosomes) increases with advancing age, which poses a risk for RIF and RPL.
Body mass index (BMI) more than 25 kg/m2 is associated with both conditions. Patients undergoing IVF require more doses of gonadotropins, yet usually a lesser number of eggs are retrieved compared to a normal BMI patient. Additionally, the quality of eggs and eventually embryo quality is also affected.
High DNA fragmentation of sperms is associated with poor quality of embryos, which would either not get implanted or might get aborted in early pregnancy.
Smoking increases the risk of miscarriage. Also, it has been found in few studies that smoking decreases the level of estrogen in the body and might also affect corpus luteum, which secretes progesterone leading to RIF.
Endometriosis is a condition in which the endometrium grows outside the uterine cavity, and secretes some immunological factors that interfere with implantation and causing RIF.
Fibroids can cause both RIF and RPL. Fibroids are non-cancerous growth from the muscle of the uterus. They might be present inside the cavity (submucosal), in the muscle (intramural) or in the outer portion (subserosal) of the uterus. Submucosal fibroids need to be removed, irrespective of the size as they might hinder implantation and growth of the baby.
Depending on the size, number, and other factors, intramural fibroids may or may not require removal. Subserosal fibroids are not found to have any effect on implantation or pregnancy.
Polyps are also non-cancerous growth that emanate from the lining of the uterus and may hinder implantation like submucosal fibroid. It needs to be removed before conception, in cases of recurrent miscarriage and before IVF cycle in cases of RIF.
It is a condition in which menstruation occurs inside the uterine muscle. Adenomyosis is strongly associated with both RIF and RPL. It is associated with altering the uterine environment to make it hostile for the embryo. Also, there is increased uterine contractions in adenomyosis, which increases the risk of abortions. It is even associated with adverse pregnancy outcomes in the 2nd and 3rd trimesters.
There are various uterine abnormalities like unicornuate, bicornuate, septate uterus etc., associated with both RIF and RPL.
Hypothyroidism is associated with infertility and RPL. Even small correction of thyroid levels is associated with better pregnancy outcomes.
APS is a condition, in which the small thrombus are formed inside the vessels and capillaries. This leads to recurrent miscarriage and might be associated with RIF. Blood tests can be done to see if a patient has APS. Precautions can be taken to avoid these complications.
Other than these factors, there are other factors like infection, thin endometrium, chronic diseases, immunological factors, molecular factors, etc, which might be responsible for these conditions.
Both recurrent implantation failure and recurrent pregnancy loss affects the couple emotionally and financially. It is a condition, which is problematic even for doctors, who are treating these couples.