Preterm birth is defined as a live birth before 37 completed weeks gestation. Some other classifications of preterm births include late preterm (34-36 weeks), moderately preterm (32-36 weeks) and very preterm (<32 weeks). These classifications are useful because they often correspond to clinical characteristics - increasing morbidities or illnesses with decreasing gestational age. Babies born too soon are often born too small. While the causes of preterm birth and low birthweight may be different in some cases, there is significant overlap within these populations of infants.
Last updated:
January 2022
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In 2021, 1 in 10 babies (10.5% of live births) was born preterm in the United States.
The rate of preterm birth in the United States is highest for black infants (14.4%), followed by American Indian/Alaska Natives (11.8%), Hispanics (10.0%), Whites (9.3%) and Asian/Pacific Islanders (9.0%).
Compared with singleton births (one baby), multiple births in the United States were about 7 times as likely to be preterm in 2021.
Notes: All race categories exclude Hispanics. Preterm is less than 37 weeks of pregnancy.
Sources: National Center for Health Statistics, final natality data. Retrieved October 4, 2023, from www.marchofdimes.org/peristats.
During 2019-2021 (average) in the United States, preterm birth rates were highest for black infants (14.4%), followed by American Indian/Alaska Natives (11.8%), Hispanics (10.0%), Whites (9.3%) and Asian/Pacific Islanders (9.0%).
Black infants (14.4%) were about 2 times as likely as Asian/Pacific Islander infants (9.0%) to be born preterm during 2019-2021 (average).
Of all live births in the United States during 2018-2020 (average), 23.7% were Hispanic, 52.1% were white, 15.2% were black, 0.8% were American Indian/Alaska Native and 6.8% were Asian/Pacific Islander.