By Lora Shahine, MD, FACOG Miscarriage is common yet often misunderstood. Approximately 25% of clinically recognized pregnancies end spontaneously, and less than 5% of women trying to conceive will have two consecutive miscarriages.1,2 When you are excited to grow your family, this grief can leave you feeling confused and wanting answers as to why it happened. The American Society of Reproductive Medicine defines recurrent pregnancy loss (RPL) as two or more consecutive miscarriages. It cites that the most common cause of miscarriage is a genetic issue or chromosome imbalance within the embryo or fetus but still recommends testing to rule out issues associated with increased risk of miscarriage. The evidence-based recommendations are reviewed here. Genetics One of the partners in approximately 2-5% of couples with recurrent miscarriage will have a balanced translocation, a chromosome rearrangement that does not impact the health of that person but puts them at higher risk of miscarriage.2 Not all offspring of this person will be affected, but a pregnancy with an unbalanced translocation will result in miscarriage. The test to diagnose a balanced translocation is a blood test called a peripheral karyotype. Antiphospholipid Syndrome (APL) APL is an autoimmune disorder that can lead to miscarriage due to blood clots. It is not inherited and requires strict clinical findings and specific blood tests. The clinical criteria include a history of one of the following: Three or more unexplained spontaneous miscarriages at less than 10 weeks gestation A single unexplained loss of morphologically normal fetus at greater than 10 weeks gestation A preterm delivery at less than 34 weeks gestation because of severe preeclampsia and/or placental insufficiency The laboratory blood tests that should be repeated 12+ weeks apart include: Lupus anticoagulant Anticardiolipin IgG or IgM Anti-beta2 glycoprotein IgM or IgG Anatomy Approximately 10-15% of women with RPL will have an anatomic cause contributing to their risk of miscarriage, such as a uterine septum, submucosal fibroid, adhesions, or large endometrial polyps. There are several tests that can evaluate the uterine cavity for anatomic issues, including: Hysterosalpingography (HSG) Sonohysterography or saline infusion sonogram (SIS) MRI Inherited Thrombophilias There are some conditions that can be inherited that can lead to an increased risk of blood clots associated with miscarriage. Routine testing is not recommended, but patients with a personal history of blood clots or a first-degree relative with known or suspected thrombophilia should be offered testing for these conditions: Factor V Leiden Prothrombin Protein C Protein S Antithrombin deficiency Hormonal/Metabolic Factors Some endocrine and metabolic conditions can lead to an increased risk of miscarriage, so screening for thyroid abnormalities, diabetes, and hyperprolactinemia are recommended. Although testing for progesterone levels does not help to determine who may need supplementation, progesterone supplements can be considered in patients with recurrent miscarriage. Conclusion It is important to realize that 50% or more of couples suffering with RPL will not find an answer with the testing options listed above. This is because 60-80% of first-trimester miscarriages tested have structural chromosomal or genetic issues that lead to the pregnancy loss. These chromosome issues are unique to each pregnancy. Although it can be frustrating to do the testing and not find an answer, remember each pregnancy is a new opportunity, and many couples with RPL will go on to have their family! References and Resources 1. ACOG. https://www.acog.org/womens-health/faqs/repeated-miscarriages. Accessed October 4, 2024. 2. ASRM. Evaluation and treatment of recurrent pregnancy loss: a committee opinion (2012) Additional references: Dugas C et al. Miscarriage. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Shehata H et al. Int J Gynecology & Obstetrics. 2023;161(S1):3-16. Shahine LK et al. Obstet Gynecol Clin North Am. 2015;42(1):117-134. Shaine LK. Not Broken: An Approachable Guide to Miscarriage and Recurrent Pregnancy Loss. Shahine; 2022. This blog is for information and education purposes only. This information is not intended to substitute professional medical advice, diagnosis, or treatment. Please consult with your physician or another qualified health provider with any questions in regards to a medical condition. A qualified healthcare professional can best assist you in deciding whether a dietary supplement is suitable based on your individual needs.
