Birth weight is the body weight of a baby at its birth. The average birth weight in babies of European descent is 3.5 kilograms (7.7 lb), with the normative range between 2.5 and 4.5 kilograms (5.5 and 9.9 lb). On average, babies of South Asian and Chinese descent weigh about 3.26 kilograms (7.2 lb). As far as low birth weight prevalence rates changing over time, there has been a slight decrease from 7.9% (1970) to 6.8% (1980), then a slight increase to 8.3% (2006), to the current levels of 8.2% (2016). The prevalence of low birth weights has trended slightly upward from 2012 to the present.There have been numerous studies that have attempted, with varying degrees of success, to show links between birth weight and later-life conditions, including diabetes, obesity, tobacco smoking, and intelligence. Low birth weight is associated with neonatal infection and infant mortality. Abnormalities
A low birth weight can be caused either by a preterm birth (low gestational age at birth) or of the infant being small for gestational age (slow prenatal growth rate), or a combination of both. Potential causes of low birth weight can also be cause by health issues in the person giving birth, genetic factors, or problems in the placenta. A very large birth weight is usually caused by the infant having been large for gestational age. Infants that are large for gestational age have been associated with significantly higher rates of neonatal morbidity.
Maintaining good nutrition by taking folic acid, which can be found in fruits and vegetables, is linked to the prevention of premature births and low birth weight. Alcohol, cigarettes, and drugs should also be avoided during pregnancy because they can also lead to poor growth and other complications. By seeing the doctor they are also able to monitor pre-existing medical illnesses to make sure they are under control during pregnancy. Mothers with high blood pressure and type 2 diabetes are more likely to have infants with low birth weights. One essential action to increase normal birth weights is to have affordable, accessible, and culturally sensitive prenatal care worldwide. This is essential not just for treating low birth weight, but also preventing it. Other prevention efforts include: smoking cessation programs, food-distribution systems, stress reduction and social service supports. See also
Infant mortality
Low birth-weight paradox
MOMO syndrome
Prenatal nutrition
Thrifty phenotype

References
Further reading
External links
MedlinePlus Encyclopedia: Intrauterine growth restriction
Fetal Growth Restriction at eMedicine