Rates of preterm birth according to gestational age in the United States

Year	Preterm birth rate (% total births)
Year	<28 weeks	28 to 31 weeks	32 to 33 weeks	34 to <37 weeks (late preterm)	All categories combined (all preterm births <37)
2021	0.6	1.0	1.2	7.7	10.5
2019	0.7	0.9	1.2	7.5	10.2
2017	0.7	0.9	1.2	7.2	9.9
2015	0.7	0.9	1.2	6.9	9.6
2010	0.7	0.9	1.2	7.2	10.0
2007	0.7	1.0	1.2	7.5	10.4

Data from: Osterman MJK, Hamilton BE, Martin JA, et al. Births: Final Data for 2021. Natl Vital Stat Rep 2023; 72:1.

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