Miscarriages are surprisingly common, and do not always indicate there will be any problems with future pregnancies or fertility. However, if you have lost two or more clinically documented pregnancies (on ultrasound) before 20 weeks, this is called RPL. “Biochemical pregnancies” are diagnosed by urine or blood testing, but disappear before anything can be seen on ultrasound. These are not typically included in the diagnosis of recurrent pregnancy loss.
What are the causes of RPL?
- Most first trimester miscarriages are due to genetic problems with the fetus. For normal development, an embryo will have 46 chromosomes that have all the genes to develop into a healthy baby. Sometimes a fetus will have an extra or missing chromosome, typically resulting in a miscarriage. As women age, the risk of a miscarriage goes up, because the genetics in our eggs gets ‘stickier’ over time. This results in extra or missing pieces of chromosomes in our eggs, and thus imbalanced numbers of chromosomes in the embryos created from these eggs.
- Some women are born with a band of tissue inside their uterus, called a uterine septum. If an embryo happens to implant on this uterine septum, it will result in a miscarriage. Other abnormalities that take up space inside the uterus such as fibroids can increase the risk of a miscarriage, if they are in or near the uterine cavity.
- Untreated hormone imbalances such as thyroid disease, diabetes, or hyperprolactinemia, can all increase the risk of a miscarriage.
- Blood Clotting
- A condition called antiphospholipid syndrome can increase the risk of blood clot formation in early placental development, which is linked to first and second trimester miscarriage.
- Smoking and excessive (over 2 drinks a day) alcohol consumption can increase the risk of a miscarriage. Obesity has also been linked with miscarriage and recurrent pregnancy loss.
What testing is done for RPL?
- Bloodwork will be done to see if you have a hormone imbalance, or blood clotting abnormality. Occasionally, a chromosome test will be done on male and female partners called a ‘karyotype’ test. Some completely healthy individuals will have differences in the way their chromosomes are arranged, called ‘translocations’. This causes them to have a high percentage of pregnancies that are genetically imbalanced, resulting in RPL. A study of the uterus will be done to ensure the inside of the uterine cavity is normal in contour. This evaluation can be done with a procedure called a saline sonogram, or with a hysterosalpingogram. Lastly, we often do genetic testing on the miscarriage tissue, to gain valuable insight into why the miscarriage occurred.
How is RPL treated?
- If during the workup a diagnosis is made, then the underlying pathology should be treated. Keep in mind that a specific diagnosis is only made 50% of the time in all couples that suffer from RPL. If the reason for RPL is not clear, we will often recommend empiric, supportive treatment, such as baby aspirin and progesterone supplementation. Some couples will chose to undergo IVF with preimplantation genetic screening (PGS) of the embryos to ensure a genetically ‘balanced’ embryo is transferred to the uterus. For some couples, this can markedly reduce the risk of future losses.