Pregnancy Loss Pregnancy Loss Causes and Risk Factors Can Breastfeeding During Pregnancy Cause Miscarriages? 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 24, 2019 Medically reviewed by Brian Levine, MD, MS, FACOG Medically reviewed by Brian Levine, MD, MS, FACOG Brian Levine, MD, MS, FACOG, is board-certified in obstetrics-gynecology, as well as reproductive endocrinology and infertility (REI). He is the director and founding partner of CCRM New York and was named a rising star by Super Doctors from 2017 to 2019. Learn about our Medical Review Board Print Getty Images/(c) Jaime Monfort Everyone's heard the advice that "breast is best" for feeding new babies, but what happens when you get pregnant with a new baby while you're still nursing your older one? Is nursing during pregnancy safe? Breastfeeding and Miscarriage Although there are numerous conflicting opinions on the issue of breastfeeding during pregnancy, no research has ever found an increased risk of miscarriage in women who continue breastfeeding an older child during pregnancy. In the past, doctors used to advise women to stop nursing when they became pregnant again. The concerns were that breastfeeding could deprive the developing baby of nutrients, or that it could stimulate uterine contractions (because breastfeeding causes increased oxytocin levels, which also can cause uterine contractions). But there is no conclusive evidence that this occurs. Babies born to mothers who breastfed during pregnancy appear to be perfectly healthy. The consensus is that it's up to the moms to decide whether to keep nursing during a new pregnancy. In a few high-risk conditions, such as placenta previa, doctors may advise increased caution. But for most, nursing during pregnancy is probably safe. Causes of Miscarriage About three of every four miscarriages occur during the first trimester of pregnancy. These miscarriages are usually attributable to a problem with the fetus. Miscarriages that happen during the second trimester are often attributable to a health problem that the mother is experiencing. Breastfeeding is unrelated to either of these. In women aged 30 years or fewer, about one of 10 pregnancies end in miscarriage. This estimate doubles among women aged 35 to 39, to two of 10 pregnancies resulting in miscarriage. What Doesn't Cause Miscarriage? Breastfeeding during pregnancy is an unlikely reason for the miscarriage. Expectant parents may also worry about sex, lifting or exercise, stress or depression, or experiencing a sudden shock or fright. None of these has been shown to cause pregnancy loss. First-Trimester Miscarriage About two of three first-trimester miscarriages are due to chromosomal abnormalities in the fetus. Often, when there are chromosomal abnormalities, the fetus doesn't have the needed information to develop properly and miscarriage results. Just because a mother experiences miscarriage due to chromosomal abnormalities once does not necessarily mean that the problem will happen again. Furthermore, a miscarriage attributable to chromosomal abnormalities doesn't mean that either the mother's or father's chromosomes are faulty. Aside from chromosomal abnormalities, other conditions and lifestyle factors may increase the risk of miscarriage during the first trimester. These include problems with the placenta, smoking, drug or alcohol use, and obesity. Second-Trimester Miscarriage During the second trimester, miscarriage is often attributable to underlying health conditions that the mother is experiencing, such as: High blood pressure Diabetes Kidney disease Autoimmune disease Thyroid disease Infections, such as syphilis, chlamydia, rubella, gonorrhea, HIV, rubella, or food-borne diseases In addition to chronic health conditions and infection, other risk factors for second-trimester miscarriage include weakened cervix, fibroids, irregularly shaped uterus, and polycystic ovarian syndrome (PCOS). 6 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. Madarshahian F, Hassanabadi M. A comparative study of breastfeeding during pregnancy: Impact on maternal and newborn outcomes. J Nurs Res. 2012;20(1):74–80. doi:10.1097/JNR.0b013e31824777c1 ACOG Practice Bulletin No. 200: Early Pregnancy Loss. Obstet Gynecol. 2018;132(5):e197–e207. doi:10.1097/AOG.0000000000002899 Eunice Kennedy Shriver National Institute of Child and Health and Human Development. What are the causes of risks for pregnancy loss (before 20 weeks of pregnancy)?. Giakoumelou S, Wheelhouse N, Cuschieri K, Entrican G, Howie SE, Horne AW. The role of infection in miscarriage. Hum Reprod Update. 2016;22(1):116–133. doi:10.1093/humupd/dmv041 Sneider K, Christiansen OB, Sundtoft IB, Langhoff-Roos J. Recurrence of second trimester miscarriage and extreme preterm delivery at 16-27 weeks of gestation with a focus on cervical insufficiency and prophylactic cerclage. Acta Obstet Gynecol Scand. 2016;95(12):1383–1390. doi:10.1111/aogs.13027 Hartmann KE, Velez Edwards DR, Savitz DA, et al. Prospective cohort study of uterine fibroids and miscarriage risk. Am J Epidemiol. 2017;186(10):1140–1148. doi:10.1093/aje/kwx062 Additional Reading La Leche League. Breastfeeding during pregnancy and tandem nursing: Is it safe?. Moscone SR, Moore MJ. Breastfeeding during pregnancy. J Hum Lact. 1993;9(2):83-8. doi:10.1177/089033449300900219 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