Table 1.

Baseline Characteristics (N = 28,516)

Age at screening, yrs	62.7 ± 7.1
Age at menopause, yrs	47.1 ± 7.3
Age at menarche, yrs	12.6 ±1.5
Reproductive duration, yrs	34.4 ± 7.4
Age at first pregnancy, yrs	20–24* (N/A)
Total number of Live births	3.3 ±1.7
History of pregnancy Loss	12,135 (42.7)
History of breastfeeding for >1 month	16,618 (58.8)
Hysterectomy prior to screening	12,098 (42.4)
Oral contraceptive use (any)	12,393 (43.5)
Menopausal hormone therapy (any)	111,012 (38.6)
Body mass index at screening, kg/m2	29.6 ± 6.2
Systolic blood pressure, mm Hg	129.1 ± 17.6
Diabetes	2,516 (8.8)
High cholesterol requiring medications	3,904 (13.9)
Smoking status
Current smoker	2,857 (10.1)
Former smoker	10,964 (38.9)
Never smoked	14,374 (51.0)
Household income
<$35,000	13,669 (51.0)
$35,000 to $74,999	9,955 (37.0)
$ $75,000	3,179 (11.9)
Education
High school and below	11,405 (40.3)
Some college and above	16,870 (60.7)
U.S. region
Northeast	5,764 (20.2)
South	8,916 (31.3)
Midwest	6,710 (23.5)
West	7,126 (25.0)
Ethnicity
American Indian	89 (0.3)
Asian or Pacific Islander	355 (1.3)
Black or African American	8,848 (31.1)
Hispanic/Latino	3,564 (12.5)
White (non-Hispanic)	15,408 (54.1)
Other	221 (0.8)

Values are mean ± SD or n (%).

^*Age at first pregnancy lasting at least 6 months was recorded as a categorical variable (age <20, 20–24, 25–29, 30–34, 35–39, 40–44, or >45 years), and the mean of the rank order was the category age 20–24 years.

N/A = not applicable.