. Author manuscript; available in PMC: 2018 Jul 1.

Published in final edited form as: Am J Obstet Gynecol. 2017 Mar 9;217(1):80.e1–80.e8. doi: 10.1016/j.ajog.2017.03.002

Table 2.

Pregnancy, neonatal, and infant outcomes among twins by maternal age group

Maternal age range, years	15–17	18–24	25–29	30–34	35–39	≥40

Preterm birth, % (n)
<34 weeks	32.7 (3,208)	24.6 (45,432)	20.5 (48,896)	18.7 (51,515)	18.4 (29,989)	20.5 (11,271)
<37 weeks	67.7 (6,641)	61.6 (113,942)	58.9 (143,456)	56.6 (156,027)	56.1 (91,565)	58.1 (31,968)

Fetal deaths, rate (n)^*	39.9 (408)	24.2 (4,597)	17.8 (4,406)	16.4 (4,591)	17.2 (2,859)	15.8 (885)

Neonatal death <28 days, rate (n)^#	10.0 (98)	7.3 (1,352)	5.5 (1,342)	4.3 (1,195)	4.6 (751)	4.3 (237)

Fetal death rate calculated per 1,000 births (live births and fetal deaths).

Neonatal death rate <28 days calculated per 1,000 live births. All outcomes in this table were calculated using a full population of US natality data (2003 revised and unrevised birth certificate).