Babies Health & Safety Low Birth Weight Baby Risks, Types, and Causes By Cheryl Bird, RN, BSN Cheryl Bird, RN, BSN Cheryl Bird, RN, BSN, is a registered nurse in a tertiary level neonatal intensive care unit at Mary Washington Hospital in Fredericksburg, Virginia. Learn about our editorial process Updated on September 30, 2020 Medically reviewed Verywell Family articles are reviewed by board-certified physicians and family healthcare professionals. Medical Reviewers confirm the content is thorough and accurate, reflecting the latest evidence-based research. Content is reviewed before publication and upon substantial updates. Learn more. by Vanessa Nzeh, MD Medically reviewed by Vanessa Nzeh, MD Facebook Twitter Vanessa Nzeh, MD, is an internal medicine and pediatrics physician who is passionate about patient advocacy, the integration of maternal and child health, as well as increasing diversity and inclusion in medical education. Learn about our Medical Review Board Print Science Photo Library/Brand X Pictures/Getty Images Low birth weight (LBW) is the medical classification for a baby who weighs less than 2500 grams—or 5 lbs 5 oz—at birth. While it may be scarier to care for a baby born at low birth weight, there aren't many differences in your day-to-day care of your newborn. However, family members of a low birth rate baby need to be extra vigilant to ensure the child stays healthy. Overview Whether your baby was born premature or at term, they can be classified as LBW. A low birth weight baby will fall into one of three categories:Low birth weight (LBW): A LBW baby weighs less than 2500 grams, or 5 lbs 5 oz.Very low birth weight (VLBW): A VLBW baby weighs less than 1500 grams, or about 3 lb 9 oz.Extremely low birth weight (ELBW): An ELBW baby weighs less than 1000 grams, or about 2 lb 3 oz. Causes Babies are born small for two main reasons: they were born early or they were born on time but didn't grow enough during pregnancy (called intrauterine growth restriction, or IUGR). There are many specific causes of low birth weight. These include prematurity, preeclampsia, or other problems with the pregnancy, smoking or substance abuse, multiple birth (twins or more), poor pregnancy nutrition, infection in the mom or baby prior to birth, including cytomegalovirus (CMV), toxoplasmosis, chickenpox, and rubella. Impact on You and Your Baby Many people think that having a baby that's born on time and just small, or a baby who's just a little early, won't cause the baby any problems. The fact is that most low birth weight babies do just fine, and have few (if any) problems caused by their small sizes. However, there are some exceptions. Here are problems low birth weight babies may experience: Issues with internal organ function: Babies born prematurely may have complications of prematurity that include problems with the function of their brain, heart, lungs, intestines, and more. Problems with blood sugar: Very small babies may have trouble regulating their blood sugar. Late preterm babies sometimes use sugar faster than they can replace it, and can easily develop dangerously low blood sugars. Problems staying warm: Small babies don't have enough fat to keep them warm. If they can't stay warm on their own, they may have to spend time in an incubator. Trouble eating: Smaller babies aren't always strong enough to breastfeed or bottle-feed well, and may need help taking in enough calories to grow. Premature Babies and Complications Watching for Complications While you cannot control the nature and severity of your baby's weight on their health, you can be watchful for complications. Premature babies are typically monitored more regularly than normal weight babies. Expect to be extra careful if your low weight baby has trouble feeding, keeping warm, or shows signs of infection. As they grow older, studies show they may be more prone to health conditions, including asthma, vision problems, and fine motor skills and hand-eye coordination. The bright side? Research from the longest running study of premature infants shows they are exceptionally resilient and may have an increased drive to succeed. What's more, parents who show more concern and advocacy for their well-being in school and social settings turn out with children who become more successful academically, socially, and physically. How Breast Milk Helps Your Premature Baby Was this page helpful? Thanks for your feedback! Track your baby’s most exciting moments with our milestone checklist. Get it free when you sign up for our newsletter. 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 0 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. Sullivan, Mary C.; Zigler, Jim. URI College of Nursing study finds effects of premature birth can reach into adulthood. University of Rhode Island Press Release. Lucile Packard's Children's Hospital at Stanford Online. "Very Low Birthweight." March of Dimes Online. Medical Resources: Low Birthweight. UCSF Children's Hospital. Intensive Care Nursery House Staff Manual. "Very Low and Extremely Low Birthweight Infants."