Low birthweight is defined as less than 2500 grams or 5 1/2 pounds. It is also common to classify low birthweight births into moderately low birthweight (1500-2499 grams) and very low birthweight (less than 1500 grams or 3 1/3 pounds). These classifications are useful because they often correspond to clinical characteristics - increasing morbidities or illnesses with decreasing birthweight. Babies born too small are often born too soon. While the causes of low birthweight and preterm birth may be different in some cases, there is significant overlap within these populations of infants.
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In 2021, 1 in 12 babies (8.5% of live births) was low birthweight in the United States.
Black infants (14.2%) were about 2 times as likely as White infants (6.9%) to be born low birthweight during 2019-2021 (average)
Compared with singleton births, multiple births in the United States were about 8 times as likely to be low birthweight in 2021.
Notes: Low birthweight is less than 2500 grams (5 1/2 pounds).
Sources: National Center for Health Statistics, final natality data. Retrieved June 3, 2023, from www.marchofdimes.org/peristats.
During 2019-2021 (average), the low birthweight rate in the United States was highest for black infants (13.9%), followed by Asian/Pacific Islanders (8.8%), American Indian/Alaska Natives (8.1%) and Whites (7.1%).
Black infants (13.9%) were about 2 times as likely as White infants (7.1%) to be born low birthweight during 2019-2021 (average)