Pregnancy Loss Causes and Risk Factors Luteal Phase and Miscarriage Luteal Phase Defect Is a Controversial Topic in Fertility Studies By Krissi Danielsson Krissi Danielsson, MD is a doctor of family medicine and an advocate for those who have experienced miscarriage. Learn about our editorial process Krissi Danielsson Medically reviewed by Medically reviewed by Brian Levine, MD, MS, FACOG on November 24, 2019 Brian Levine, MD, MS, is board-certified in obstetrics and gynecology as well as in reproductive endocrinology and infertility. Learn about our Review Board Brian Levine, MD, MS, FACOG on November 24, 2019 Print khoa vu/Getty Images In testing for infertility causes or as part of recurrent miscarriage testing, your physician might bring up the term luteal phase defect, or a shortened luteal phase. Here's what these statements mean. About the Luteal Phase of the Menstrual Cycle The term luteal phase usually refers to the second half of the menstrual cycle — the time from ovulation to the start of the menstrual period. In women with a standard 28-day menstrual cycle and who ovulate on the fourteenth day, the luteal phase is 14 days long. One characteristic of the menstrual cycle is that lots of things are going on in your body at any given time. In the first half of your menstrual cycle, various hormonal fluctuations take place to prepare an egg for ovulation and ultimately to cause ovulation. During the luteal phase, the major hormonal event is the rise of progesterone levels and the uterine lining's preparation to receive a fertilized egg (in the event that conception has occurred). The Relationship Between Luteal Phase Defects and Miscarriages Luteal phase defect (also called luteal phase dysfunction or luteal phase deficiency) means that a problem exists with the luteal phase, with the result being that the uterine lining might not be optimally prepared for implantation of a fertilized egg. Luteal phase defect is a theoretical cause of infertility as well as early miscarriages. The idea underlying luteal phase defect is that if the uterus is not fully prepared to support a pregnancy, then either a woman will not get pregnant at all or the pregnancy will not implant properly and will ultimately miscarry. Luteal phase defect results in a shorter than average luteal phase (a woman getting her period 10 days after ovulating rather than 13 or 14 days afterward). Progesterone Therapy and Endometrial Biopsy Some people believe that low progesterone might be at the root of recurrent miscarriages; a woman with a luteal phase defect and low progesterone would theoretically be less able to support a pregnancy. Supplementing progesterone to prevent miscarriage is a controversial treatment, however, because no scientific evidence has ever proven that progesterone supplementation improves pregnancy outcomes. In decades past, an endometrial biopsy was sometimes performed to take a look at the cellular or histological makeup of the endometrial (uterine) lining and figure out whether its maturity lagged behind what was expected. However, there is so much variability in how the uterine presents cellularly that an endometrial biopsy is no longer considered useful. Was this page helpful? Thanks for your feedback! Get diet and wellness tips delivered to your inbox. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Family uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Shah D, Nagarajan N. Luteal insufficiency in first trimester. Indian J Endocrinol Metab. 2013;17(1):44–49. doi:10.4103/2230-8210.107834 Mesen TB, Young SL. Progesterone and the luteal phase: a requisite to reproduction. Obstet Gynecol Clin North Am. 2015;42(1):135–151. doi:10.1016/j.ogc.2014.10.003 Coomarasamy A, Williams H, Truchanowicz E, et al. A Randomized Trial of Progesterone in Women with Recurrent Miscarriages. N Engl J Med. 2015;373(22):2141-8. doi:10.1056/NEJMoa1504927