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The Sister Study

Reproductive Characteristics

The percentages for each characteristic may not add up to 100 due to rounding. The number of missing or not applicable were excluded from the total (N = 50,884) for calculating of percentages. 

Age (in years) when Participant's Periods Started Number of Participants Percentage

11 or younger

12-13

14 or older

Never menstruated

Missing

10,405

28,525

11,909

7

38

20%

56%

23%

--

--

 

Parity (number of live births) Reported by Participant Number of Participants Percentage

0 live births

1 live birth

2 live births

3 live births

4 live births

5 or more live births

Missing

9,246

7,442

18,868

10,124

3,482

1,687

35

18%

15%

37%

20%

7%

3%

--

 

Age (in years) of Participant at First Live Birth Number of Participants Percentage

19 or younger

20-24

25-29

30-34

35 or older

No Live Births

Missing

6,822

15,892

11,525

5,225

2,130

9,246

44

16%

38%

28%

13%

5%

--

--

 

Participant Reports Breastfeeding Child/Children Number of Participants Percentage

Yes: breastfed

No: never breastfed

Missing

28,945

21,904

35

57%

43%

--

 

Participant Reports Use of Hormonal Birth Control Number of Participants Percentage

Yes: used

No: never used

Missing

43,122

7,724

38

85%

15%

--

 

Menopausal Status of Participant at Time of Baseline Enrollment Number of Participants Percentage

Natural menopause

Surgical menopause

Premenopause

Unknown/missing

20,377

12,357

18,120

30

40%

24%

36%

--

 

Participant Reports Use of Hormone Replacement Therapy
(estrogen/progesterone)
Number of Participants Percentage

Yes: used

No: never used

Missing

23,050

27,675

159

45%

55%

--

 

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