Recurrent miscarriages can be an extremely distressing experience, both physically and psychologically, for couples. The repeated loss of eagerly anticipated pregnancies can lead to deep sadness and a sense of helplessness. However, thanks to advancements in modern medicine and reproductive technologies, the causes of this condition are now better understood, and effective treatment approaches can be offered in many cases. At Ankara IVF Center, we aim to support our couples through this challenging journey with a scientific and compassionate approach. In this article, we will explore the causes of recurrent miscarriages and current treatment approaches with the expertise of Prof. Dr. Mehmet Çınar.
Definition of Recurrent Miscarriage
Recurrent miscarriage is generally defined as two or more consecutive pregnancy losses. Also known as "recurrent pregnancy loss" (RPL) in medical literature, this condition is characterized by the spontaneous termination of a pregnancy before the 20th week of gestation. The vast majority of pregnancy losses occur in the first trimester, i.e., within the first 12 weeks. While approximately 15-20% of pregnancies in the general population result in miscarriage, the rate among couples experiencing recurrent miscarriage is around 1-2%. Although the definition generally refers to two or more miscarriages, some experts argue that even a single pregnancy loss may warrant a detailed investigation, especially if the expectant mother is of advanced maternal age or has difficulty conceiving. Understanding the causes of recurrent miscarriages is critically important for determining accurate diagnostic and treatment strategies.
Genetic Causes
One of the most common causes of recurrent miscarriages is genetic factors. Approximately 50-60% of pregnancy losses are due to chromosomal abnormalities in the embryo. These abnormalities usually occur randomly during fertilization and hinder the healthy development of the embryo, leading to early pregnancy termination.
Embryonic Chromosomal Abnormalities
Numerical (e.g., trisomy, monosomy) or structural chromosomal abnormalities in the embryo are among the most common factors preventing the continuation of pregnancy. This condition often results from errors occurring during the formation of egg or sperm cells, even if there is no problem in the couple's genetic makeup. Advanced maternal age, in particular, increases the risk of chromosomal abnormalities in the embryo due to declining egg quality.
Parental Chromosomal Abnormalities
In approximately 2-5% of couples experiencing recurrent miscarriages, structural chromosomal abnormalities such as balanced translocations may be detected in either the mother or the father. In such cases, even though the parents are healthy, the sperm or egg cells they produce may carry unbalanced chromosome sets. This leads to some embryos being genetically problematic and thus resulting in miscarriage. In such situations, Preimplantation Genetic Testing (PGT) can increase the chances of pregnancy by identifying and transferring healthy embryos. PGT allows for the genetic examination of cell samples taken from embryos during in vitro fertilization (IVF) treatment.
Anatomical and Hormonal Causes
Abnormalities in uterine structure or hormonal imbalances can also be significant causes of recurrent miscarriages. These factors can prevent the embryo from implanting in the uterus or developing healthily.
Anatomical Causes
- Uterine Anomalies: Congenital uterine malformations, such as a uterine septum, double uterus (uterus didelphys), or heart-shaped uterus (bicornuate uterus), can create an unsuitable environment for embryo implantation and development. A uterine septum is one of the most common anomalies and can be surgically corrected.
- Intrauterine Adhesions (Asherman's Syndrome): Adhesions formed inside the uterus after previous curettages, infections, or surgical interventions can narrow the uterine cavity or impair the function of the endometrium (lining of the uterus), leading to miscarriages.
- Fibroids and Polyps: Fibroids (submucosal fibroids) growing into the uterine cavity or intrauterine polyps can prevent embryo implantation or cause miscarriages in later stages of pregnancy.
- Cervical Insufficiency: This is a condition where the cervix painlessly opens in later weeks of pregnancy, leading to miscarriage or preterm birth. This typically occurs in second-trimester miscarriages.
These anatomical problems can generally be diagnosed with methods such as hysterosalpingography (HSG), ultrasonography, sonohysterography, or direct visualization through hysteroscopy and laparoscopy, and can often be corrected with surgical interventions.
Hormonal Causes
- Thyroid Disorders: Both hypothyroidism (underactive thyroid gland) and hyperthyroidism (overactive thyroid gland) can have negative effects on pregnancy and increase the risk of miscarriage. Regulating thyroid hormone levels is important for pregnancy success.
- Polycystic Ovary Syndrome (PCOS): PCOS can lead to hormonal imbalances, affecting egg quality, and causing insulin resistance and increased androgen levels. These conditions can increase the risk of miscarriage.
- Luteal Phase Defect (LPD): This is a condition where the uterine lining (endometrium) does not adequately prepare for embryo implantation after ovulation. Although associated with progesterone deficiency, scientific evidence regarding its direct causation of recurrent miscarriages is controversial, and routine treatment is not always recommended.
- Diabetes: Uncontrolled diabetes, especially high blood sugar levels, can significantly increase the risk of miscarriage. Achieving blood sugar control before and during pregnancy is critically important.
Coagulation Disorders
Coagulation disorders, also known as thrombophilias, are conditions that cause blood to clot more easily than normal