Gestational age and birth weight characteristics by plurality: United States, 2021

	Singletons	Twins	Triplets	Quadruplets	Quintuplets and higher order multiples*
Total number of births	3,547,198	114,161	2785	133	15
Preterm (<37 weeks GA)^¶	8.8%	62%	99%	99%	100%
Early preterm (<34 weeks GA)^¶	2.2%	20%	66%	98%	100%
Low birth weight (<2500 g)	6.9%	56%	95%	99%	100%
Very low birth weight (<1500 g)	1.1%	9%	35%	70%	73%

GA: gestational age.

* Quintuplets, sextuplets, and higher order multiple births are not differentiated in the national data set.

¶ Categories of prematurity are defined by the number of completed weeks of gestation.

Reproduced 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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