Table 3.

Hazard Ratios and 95% CIs for the Risk of CHD and Stroke According to Age at First Report of Infertility Among 103 729 Women (NHSII, 1989–2017)

	No infertility	Age at first report of infertility			P value, test for trend§
		≤25 y	26–30 y	>30 y
CHD||
Events, n	966	230	240	64
Person‐years	1 676 149	238 335	376 255	115 744
Age‐adjusted model*	1.00 [Referent]	1.43 (1.24–1.65)	1.07 (0.92–1.23)	0.87 (0.68–1.13)	<0.001
Multivariable model 1†	1.00 [Referent]	1.40 (1.21–1.63)	1.10 (0.95–1.28)	0.88 (0.68–1.14)	<0.001
Multivariable model 2‡	1.00 [Referent]	1.26 (1.09–1.46)	1.08 (0.93–1.25)	0.91 (0.70–1.19)	0.004
CVD¶
Events, n	1489	311	351	99
Person‐years	1 675 650	238 263	376 140	115 711
Age‐adjusted model*	1.00 [Referent]	1.27 (1.12–1.44)	1.01 (0.90–1.13)	0.87 (0.71–1.07)	0.004
Multivariable model 1†	1.00 [Referent]	1.25 (1.10–1.42)	1.04 (0.92–1.17)	0.87 (0.70–1.07)	0.003
Multivariable model 2‡	1.00 [Referent]	1.14 (1.01–1.29)	1.02 (0.90–1.15)	0.90 (0.73–1.11)	0.08
Stroke
Events, n	531	83	111	37
Person‐years	1676 650	238 514	376 389	115 787
Age‐adjusted model*	1.00 [Referent]	0.98 (0.77–1.23)	0.89 (0.73–1.10)	0.89 (0.64–1.25)	0.43
Multivariable model 1†	1.00 [Referent]	0.97 (0.77–1.23)	0.91 (0.74–1.12)	0.89 (0.63–1.25)	0.50
Multivariable model 2‡	1.00 [Referent]	0.91 (0.72–1.15)	0.90 (0.73–1.12)	0.91 (0.64–1.28)	0.28

BMI indicates body mass index; CHD, coronary heart disease; CVD, cardiovascular disease; ICD‐8, International Classification of Diseases, Eighth Revision; MI, myocardial infarction; and NHSII, Nurses’ Health Study II.

^*Models were jointly stratified by age (months) and calendar time (months).

^† Model 2 additionally adjusted for age at menarche (<12, 12, 13, ≥14 years of age), White Non‐Hispanic race and ethnicity (yes, no), marital status (ever married, never), daily aspirin use (yes, no), oral contraceptive use (never, past, current), gravidity (≤1, 2, 3, or ≥4 pregnancies), BMI at age 18 years (<19, 20.5–21.9, 22–24.9, 25–29.9, or ≥30 kg/m²), and breastfeeding duration (<3, 3–12, or >12 months).

^‡ Model 3 is additionally adjusted for current BMI (<24.9, 25–29.9, 30–34.9, or ≥35 kg/m²), cigarette smoking status and current dose (never, past, current 1–34 cigarettes/d, current ≥35 cigarettes/d), physical activity (0, 0.1–1.0, 1.1–2.4, 2.5–5.9, or ≥6 h/wk), and Alternative Healthy Eating Index 2010 diet quality score (quintiles).

^§ Tests for linear trend were conducted by modeling categories of age at first report of infertility as an ordinal variable assigning integer values.

^|| CHD includes fatal and nonfatal MI, fatal coronary heart disease (ICD‐8: 410, 412), and self‐reported coronary artery bypass grafting/angioplasty/stent.

^¶ CVD includes CHD and fatal and nonfatal cerebrovascular accident or transient ischemic attack (ICD‐8: 430–437).