Low Birthweight (LBW) is a term used in the pregnancy and birthing industry to describe babies who are born weighing less than 5.5 pounds (2,500 grams). LBW is often used as a synonym for preterm birth, which describes any baby born before 37 weeks gestation.
There are many possible causes of LBW, including maternal malnutrition, smoking during pregnancy, alcohol consumption during pregnancy, drug use during pregnancy, infections, preeclampsia/eclampsia, intrauterine growth restriction, stress, multiple gestations, preterm labor, or low socioeconomic status. Some of these factors are modifiable (such as nutrition and smoking), while others are not. Regardless of the cause(s), all babies born at a low birth weight are at increased risk for adverse outcomes.

Risk Associated with LBW
Babies who are born with LBW are at risk for a number of health problems. They may have trouble breathing and feeding; they’re more likely to develop an infection, and they’re at higher risk for cerebral palsy and developmental delays, as well as chronic lung disease, and heart disease. In addition, because their bodies aren’t fully developed yet, they may have difficulty regulating their body temperature and blood sugar levels. Low birth weight is also one of the leading causes of infant mortality.
Fortunately, there have been significant advancements in medical care for high-risk pregnancies that have led to improved outcomes for both mother and child. However, given the complex nature of this problem – with numerous potential causative factors – further research is needed to fully understand all aspects of LBW and how best to prevent it.
This image shows how often the term ‘Low Birthweight’ is used in relation to other, similar birth terms:

Other Terms Related to LBW
There are a number of other terms that are related to low birth weight, including:
-Preterm birth: This term is used to describe any baby born before 37 weeks gestation.
-Very Low Birthweight (VLBW): This term is used to describe babies who are born weighing less than 3.3 pounds (1,500 grams).
-Extremely Low Birthweight (ELBW): This term is used to describe babies who are born weighing less than 2.2 pounds (1,000 grams).
-Proportion of LBW: This term refers to the percentage of babies born at a particular gestational age who weigh less than 5.5 pounds (2,500 grams).
– LBW rate: This term refers to the number of babies born per 1,000 births who weigh less than 5.5 pounds (2,500 grams).
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