Pregnancy Loss Pregnancy Loss Causes and Risk Factors Causes of Miscarriage in the Second Trimester By Krissi Danielsson 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 Updated on November 29, 2022 Medically reviewed by Alyssa Dweck, MD Medically reviewed by Alyssa Dweck, MD LinkedIn Alyssa Dweck, MD, MS, is a board-certified gynecologist and an assistant clinical professor at the Mount Sinai School of Medicine. She provides care to women of all ages, and she has delivered thousands of babies. Learn about our Medical Review Board Print Verywell / Nusha Ashjaee Table of Contents View All Table of Contents Chromosomal Abnormalities Congenital Defects Placental Problems Cervical Insufficiency Infections Chronic Conditions Thrombophilia Abdominal Trauma Drug and Alcohol Use Unknown Causes A miscarriage in the second trimester is a pregnancy loss that happens specifically between 13 weeks 0 days and 20 weeks 0 days of gestation. The incidence of second trimester loss up to 20 weeks is less than 1%. (After this time, the loss is more accurately classified as a stillbirth or neonatal death.) No matter the timing, it's only natural to want answers when such an event occurs. Miscarriage at 14 Weeks A second trimester miscarriage—or late miscarriage as it is sometimes called—refers to a miscarriage that happens when a baby dies during the second trimester. When this happens, you and your healthcare provider will likely discuss various treatment options for second trimester miscarriage. Causes of second-trimester miscarriage vary, but, in most cases, the pregnancy loss isn't due to anyone's actions. Oftentimes, even your doctor won't be able to explain why it happened. Chromosomal Abnormalities Chromosomal abnormalities, such as trisomies, are a major cause of almost all forms of pregnancy loss. Second-trimester miscarriages are caused by these abnormalities about one-quarter of the time. Prenatal testing may have made you aware of the potential for this, but that is not always the case. Unlike a first-trimester pregnancy loss, second-trimester miscarriages are less likely to be caused by a chromosomal abnormality. All told, around a third of second-trimester losses are a result of genetic aberration. Congenital Defects Congenital birth defects are those that are often inherited but may also be caused by an infection during pregnancy or exposure to certain teratogenic (defect-causing) medications, chemicals, or toxins. Birth defects such as heart or brain malformations in your developing baby can make your pregnancy a nonviable one. Depending on the type and severity of the birth defect, your doctor may be able to diagnose any potential problems via ultrasound. Others may be detected during routine prenatal screenings. 5 Infections That Cause Birth Defects Placental Problems One such problem is called a placental abruption. If your placenta—the structure that's attached to the wall of the uterus and gives nutrients to your baby via the umbilical cord—suddenly peels off the wall of the uterus before you're ready to give birth, this can prevent your developing baby from getting necessary nutrients and oxygen. Symptoms of placental abruption include vaginal bleeding, abdominal pain, uterine contractions, cramping, and back pain during the last 12 weeks of pregnancy. Cervical Insufficiency Cervical insufficiency, also known as an incompetent cervix, means your cervix is weak and begins dilating and opening too soon. Some women experience cervical insufficiency after having a challenging birth or after having a cervical procedure such as loop electrosurgical excision procedure (LEEP), laser ablation, or cold knife conization. Others develop the condition due to congenital uterine malformations. Symptoms of cervical insufficiency include backache, vaginal bleeding, abdominal cramps, pelvic pressure, and vaginal discharge, usually between 14 and 20 weeks of pregnancy. Some are completely asymptomatic. Infections That Cause Miscarriages Uterine infection is another possible cause of miscarriage, although it is a more common cause in developing countries than in the United States. Still, any untreated or severe uterine infection may trigger the spontaneous loss of a pregnancy, including: Bacterial vaginosisChlamydiaGonorrheaTrichomoniasisViral vaginitis Poorly Controlled Chronic Conditions Chronic diseases in the mother can also increase the risk for pregnancy loss. In many cases, the risk increases if the disease is poorly controlled with medications or lifestyle. Other chronic conditions carry an inherent risk of pregnancy loss depending on their severity. Examples include: Autoimmune diseases like scleroderma and antiphospholipid syndrome Diabetes Hypertension (high blood pressure) Polycystic ovary syndrome (PCOS) Thyroid disease The risk can be further increased in women who smoke, are obese, or have hormone problems. Thrombophilia During Pregnancy Thrombophilia is an increased risk of forming blood clots in blood vessels like veins and arteries that may be due to a genetic abnormality or a problem with your immune system, such as in lupus. This can cause problems involving your placenta and your umbilical cord. Thrombophilia is sometimes treated during pregnancy with blood-thinning drugs or with low-dose aspirin. Symptoms of thrombophilia include pain, swelling, and tenderness in your leg, usually in your calf, as well as red or warm skin (particularly at the back of your leg below the knee). Abdominal Trauma Any trauma such as an automobile accident, fall, or being hit in the abdomen can hurt both you and your developing baby and potentially cause a miscarriage. In a car, always wear a seat belt, placing the lap belt under the uterus and putting the shoulder strap between your breasts. Avoid high-impact physical activities that might cause you to lose your balance. Try not to let your kids roughhouse with you, if you can avoid it. If you are a victim of domestic violence, call 1-800-799-SAFE, the National Domestic Violence Hotline. Can Being Hit in the Stomach Cause Miscarriage? Drug and Alcohol Use Cocaine and methamphetamine are especially linked to miscarriage. Studies have shown that the use of illegal drugs has been associated with low birth weight, premature labor, placental abruption, and fetal death. Alcohol has also been cited as a cause of pregnancy loss during not only the first trimester but the second trimester as well. According to research from the University of Copenhagen, light drinking (defined as one to two drinks per week) increases the odds of an early second-trimester miscarriage by 70%. Unknown Causes of Miscarriage Sometimes a pregnancy loss occurs for no apparent reason and, no matter how much a doctor investigates, no cause can be found. As distressing as this may be, it does happen and more frequently that one might think. Moreover, having had a prior second-trimester miscarriage in and of itself is a risk factor for subsequent second-trimester miscarriages. While the cause may be identified in some women (like cervical insufficient or uterine defects), others will remain a mystery. According to research from the University of Pennsylvania, women with a prior second-trimester miscarriage were 10.8 times more likely to have recurrent second-trimester losses compared with women who previously delivered at term. A Word From Verywell If you've had second-trimester pregnancy loss and are pregnant again, consult your doctor early in your pregnancy in case extra monitoring may be needed. A miscarriage of a prior pregnancy doesn't necessarily mean that a woman is at high risk, as most women go on to have healthy pregnancies. Calculating Your Risk of Miscarriage 8 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. Wyatt PR, Owolabi T, Meier C, Huang T. Age-specific risk of fetal loss observed in a second trimester serum screening population. Am J Obstet Gynecol. 2005;192(1):240-246. doi:10.1016/j.ajog.2004.06.099 Edlow AG, Srinivas SK, Elovitz MA. Second-trimester loss and subsequent pregnancy outcomes: What is the real risk? Am J Obstet Gynecol. 2007;197(6):581.e1-6. doi:10.1016/j.ajog.2007.09.016 World Health Organization. Congenital anomalies. ACOG Practice Bulletin No.142: Cerclage for the management of cervical insufficiency. Obstet Gynecol. 2014;123(2 Pt 1):372-379. doi:10.1097/01.AOG.0000443276.68274.cc Allanson B, Jennings B, Jacques A, Charles A, Keil A, Dickinson J. Infection and Fetal Loss in the Mid-Second Trimester of Pregnancy. Obstet Gynecol Surv. 2010;65(10):613-614. doi:10.1097/ogx.0b013e3182021f22 Eunice Kennedy Shriver National Institute of Child Health and Human Development. What Are the Causes of and Risks for Pregnancy Loss (Before 20 Weeks of Pregnancy)? Ormesher L, Simcox L, Tower C, Greer IA. Management of inherited thrombophilia in pregnancy. Womens Health (Lond). 2016;12(4):433-441. doi:10.1177/1745505716653702 Andersen AM, Andersen PK, Olsen J, Grønbæk M, Strandberg-Larsen K. Moderate alcohol intake during pregnancy and risk of fetal death. Int J Epidemiol. 2012;41(2):405-413. doi:10.1093/ije/dyr189 Additional Reading Hawkins Bressler L, Correia KF, Srouji SS, Hornstein MD, Missmer SA. Factors associated with second-trimester pregnancy loss in women with normal uterine anatomy undergoing in vitro fertilization. Obstet Gynecol. 2015;125(3):621-7. doi:10.1097/AOG.0000000000000667 By Krissi Danielsson Krissi Danielsson, MD is a doctor of family medicine and an advocate for those who have experienced miscarriage. See Our Editorial Process Meet Our Review Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit