Table 2.

Hazard ratios (95% confidence intervals) for preterm delivery in first pregnancy and cardiovascular events (MI and stroke)

	Term: ≥37 weeks (n=64,004)	Preterm: <37 weeks (n=6,178)	Moderate Preterm: ≥32 to <37 weeks (n=4,712)	Very Preterm: <32 weeks (n= 1,466)	p-trend‡
Cases/Person-Years	831/2,023,726	118/189,048	75/143,199	43/45,849
Model 1*	1.00 (ref)	1.54 (1.27, 1.87)	---	---	---
Model 2*	1.00 (ref)	1.47 (1.21, 1.79)	---	---	---
Model 3*	1.00 (ref)	1.42 (1.16, 1.72)	---	---	---
Model 1†	1.00 (ref)	---	1.30 (1.03, 1.65)	2.27 (1.67, 3.08)	<0.0001
Model 2†	1.00 (ref)	---	1.27 (1.01, 1.61)	2.05 (1.50, 2.81)	<0.0001
Model 3†	1.00 (ref)	---	1.22 (0.96, 1.54)	2.01 (1.47, 2.75)	<0.0001

Model 1 is adjusted for age at first birth, age in 1989, race/ethnicity, and parental education

Model 2 is additionally adjusted for pre-pregnancy BMI, pre-pregnancy smoking, pre-pregnancy Alternative Healthy Eating Index (AHEI) score (in quintiles), pre-pregnancy alcohol intake, physical activity at age 18, and pre-pregnancy oral contraceptive use

Model 3 is additionally adjusted for pre-pregnancy chronic hypertension, pre-pregnancy hypercholesterolemia, pre-pregnancy type 2 diabetes mellitus, and family history of MI or stroke before age 60

^*Compares preterm (<37 weeks) to term (≥37 weeks)

^†Preterm category is split into moderate preterm (≥32 to <37 weeks) and very preterm (<32 weeks)

^‡For trend test, the measure of prematurity was included model as a continuous variable with most common gestation length as the value to represent each category