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Table 2 Characteristics of Included Studies, by Year of Publication – Cohort Studies (N = 14)

From: Age at first birth and risk of later-life cardiovascular disease: a systematic review of the literature, its limitation, and recommendations for future research

First author, publication year

Duration of study + years of FU

Location of study

Exclusion criteria

Cohort size

Number of cases

(% of cohort)

Age at entry

Endpoint category a

Specific endpoint

CHD

CVA

CVD

Colditz

1987 [26]

En: ‘76

F: until ‘82

FU: 6 y

USA

Diagnoses of CHD at entry, non-married. (Note: only registered nurses, 98% white)

119,963 women. 700,809 person years

308 (2.6%)

30–55 at entry

C

  

Incident cases non-fatal myocardial infarction or fatal CHD.

Cooper

1999 [27]

En: ‘34-‘39

F: until ‘90–‘91.

FU: 51–57 y

Minne-sota, USA

Enrolled white college students. In FU excluded if missing information age CVD event, or missing CVD data in questionnaire

867. (714 self-administered FU, 153 proxy respondents (family members))

45 (35 non-fatal, 10 fatal) (5.2%)

Under 25 at entry, 63–81 at FU

C

  

Non-fatal and fatal CHD

Otterblad- Olausson

2004 [9]

En:‘85 census. FU: From ‘90-‘95.

FU: 5 y

Sweden

Women who had first infant before the age of 30 between 1964 and 1989 are included. Exclusion: women who emigrated or died between census and follow up.

460,434 women

151 (total circulatory) (0.05%), no data reported for CHD and cerebrovascular.

Born ‘50 – ‘64 → 21 to 35 at census.

M

M

M

Total circulatory, CHD, cerebrovascular mortality.

Yang CY

2006 [38]

En: ‘78/‘87

F: until ‘03 FU: 16–25 y

Taiwan

Included women with a first and singleton childbirth between 1978 and 1987.

1,292,462 women, 27,402,995 person years

189 (0.01%)

?

 

M

 

Subarachnoid hemorrhage mortality

Henrettab

2007 [30]

En: ‘31/‘41

F: ‘92/‘02a

USA

First two follow up years excluded. People who didn’t survive until follow up excluded.

4335 women

Heart disease: 13.2%, stroke: 8.9% (parous women)

Birth cohort ‘31-‘41. Age at FU: 51–61 through 61–71

E

E

 

Presence of disease in 1994: heart, stroke. Self-reported.

Sakauchi

2007 [36]

En:‘88/‘90

F: until ‘03. FU: 13–15 y

Japan

Previous history of cancer. Missing target question item.

63,600 women at baseline, 817,669 person years

CHD: 458 (0.7%)

Cerebrovascular: 1151 (1.8%)

40 to 79 at entry.

M

M

 

CHD mortality, cerebrovascular mortality

Yang L

2009 [39]

En: ‘91-‘92

F: until ‘04. FU: avg. 12.9 y

Sweden

Prior CVD. Missing information on OC use or smoking. Baseline self-reported natural menopause or HRT use.

45,729

Stroke: 285 (0.6%);

Ischemic: 193 (0.4%) Hemorrhagic: 72 (0.2%)

30–49

 

C

 

Ischemic and Hemorrhagic stroke.

Grundy

2010 [29]

En: ‘35/‘68

F:’ from ‘80 to ‘03.

FU: 23 y

Norway

Analysis restricted to ages above 45 (largely completed childbearing for women). Men and women who died before this age were excluded

744,784 women (7.2 million person years) 785,317 men (7.36 million person years)

3605 women (0.5%)

12,640 men (1.6%)

Register data born ‘35-‘68. Mortality at 45–68

  

M

Death from circulatory diseases

Chang

2011 [25]

En: ‘85

FU: until ‘05

FU: 20 y

Kangwha, Korea

Ever on OC. Missing info on age menarche, MP, BMI, BP, AFB, gravidity or parity.

3257 women. 48,313 person years

478 (14.7%)

PostMP, 55 or older at entry

M

M

M

CVD mortality, CHD mortality, stroke mortality

Gallagher

2011 [28]

En: ‘89-‘91

F: until ‘00

FU: 10/12 y

China

None mentioned

267,400 women. 2,565,433 person years

CVD: 4349 (1.6%), Stroke: 2776 (0.9%), CHD: 494 (0.2%).

30–60 at entry

M

M

 

CHD, ischemic and hemorrhagic stroke mortality.

Webb

2011 [10]

En: ‘70

F: until ‘06 FU: max 37 y

England and Wales

Included women estimated to have reached age 13 during ‘70s-‘90s, sampled members of census ‘71, ‘81 and ‘91.

1,913,595 person years

133 (0.007%)

13–49

M

  

Heart disease mortality

Merritt

2015 [32]

En: ‘92/‘00

F: Until ‘10.

FU: mean 12.9 y

10 western European countries

DM, myocardial infarction, angina, stroke, cancer. Report of a prevalent disease that could influence important confounders. Missing lifestyle questionnaire, vital status or date of death. Women reported never having menstruated or missing information on all reproductive variables.

322,972 women

Circulatory: 2404 (0.7%); Cerebrovascular: 808 (0.3%);

CHD: 732 (0.2%)

25–70 at entry

M

M

M

Total circulatory, cerebrovascular, and CHD mortality

Barclay

2016 [22]

En: ‘32 - ‘60

F: ‘90 - ‘12

FU: 22 y

Sweden

This is a sibling study: ID for both parents needed, no multiple births, no only children, no childless individuals, no variance on either mortality or AFB.

12,635 women, 27,183 men

4503 women (35.6% 10,067 men (37.0%)

People enter cohort in ‘90 or after age 45. Ages 45–80 throughout follow-up.

  

M

Circulatory deaths

Parikh

2016 [35]

En: ‘91

F: until ‘10

FU: median 12 years

USA

Missing reproductive and CHD risk factor information, missing follow up, prevalent or unknown history of CHD.

72,982

4607(6.3%)

Mean age at start of study 63.2

E

  

Coronary Heart Disease events

  1. En entry in to study, F follow-up until, FU follow up time in years, OC oral contraceptives, MP menopause, BMI Body mass index, BP blood pressure, AFB age at first birth;
  2. aThis column provides an overview of study endpoint category (coronary heart disease (CHD), cerebrovascular disease (CVA), cardiovascular disease (CVD)) and whether it concerns events (E), mortality (M) or a combination (C) of events and mortality
  3. bThe data used for this article are drawn from a cohort study. However, the data on stroke and heart disease are cross sectional on presence of heart disease in 1994