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.
Last updated:
January 2022
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In 2022, 1 in 13 babies (7.8% of live births) was low birthweight in Arizona.
Black infants (13.2%) were about 2 times as likely as White infants (7.0%) to be born low birthweight during 2020-2022 (average)
Compared with singleton births, multiple births in Arizona were 8 times as likely to be low birthweight in 2022.
Notes: Very low birthweight is less than 1500 grams (3 1/3 pounds).
Sources: National Center for Health Statistics, final natality data. Retrieved March 19, 2024, from www.marchofdimes.org/peristats.
Maternal age is a risk factor for very low birthweight, with higher rates found among the youngest and oldest mothers.
In Arizona during 2020-2022 (average), very low birthweight rates were highest for women ages 40 and older (1.5%) and under age 20 (1.4%) , compared to 1.2% for all live births.