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Table 3 Age at First Birth and CVD – Case Control Studies (N = 6), by Year of Publication

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

Case control studies
First author, publication year Age at first birth Exposure cases: N (%) Exposure controls
N (%)
Point estimate (+CI) a
Base model
Point estimate (+CI) a
Final model
Adjusted for or matched on. If underlined, also adjusted in base model. Notes on study considerations and limitations.
Beard
1984 [23]
< 20 Data not provided Data not provided   1.9 (0.7–5.6) D: age; SE: - BM: HT, DM; HB: smoking; R: - No data on number of individuals per exposure group. Likely number for <20 group is small.
20–24 1.8 (1.1–3.3)
≥25/n.a. b 1 (Ref)
La Vecchia
1987 [31]
< 20 21 (10.4) 23 (6.1)   2.31 (1.1–4.9) c D: age; SE: - BM: - HB: - R: - Nulliparous group includes young women who did not have children yet.
20–24 71 (35.1) 117 (31.3) 1.47 (0.9–2.4)
≥ 25 75 (37.1) 111(29.7) 1.39 (0.8–2.4)
Nullipara 35 (17.3) 123 (32.9) 1 (ref)
Talbott [37]
1989
<20 14 (26.9) 7 (10.3) 3.4 (1.1–9.9) 2.5 (0.5–12.8) D: age at demise (base model) SE: - BM: - HB: smoking (final model); R: - No adjustment for age in final model, despite much younger controls. Small sample size. Caucasian-only controls; no race/ethnicity information for cases.
≥ 20 38 (73.1) 61 (89.7)
Palmer
1992 [34]
< 18 34 (4.5) 5 (0.7) 6.8 5.5 (1.7–17) D: marital status (and age-matched); SE: education, education spouse, occupation; BM: drug-treated HT, elevated serum cholesterol, drug-treated DM, family history MI, BMI; HB: smoking, coffee, alcohol, physical activity; R: conjugated estrogen use, age menarche, parity, menopausal status Extensive adjustment in final model
18 33 (4.3) 31 (4.2) 1.2 1.1 (0.6–2.2)
19 65 (8.5) 39 (5.3) 1.6 1.6 (0.9–2.8)
20–24 376 (49.4) 366 (49.4) 1 1 (ref)
25–29 177 (23.3) 224 (30.2) 0.7 0.8 (0.6–1.1)
30–34 61 (8.0) 58 (7.8) 1.0 1.3 (0.8–2.2)
≥ 35 15 (2.0) 18 (2.4) 0.8 1 (0.4–2.9)
<20 132 (17.3) 75 (10.1) CI not provided 1.7 (1.1–2.6)
≥ 20 629 (82.7) 666 (89.9) 1 (ref)
Okamoto
2001 [33]
< 27 61 (49.0) 146 (58.8)   1 (ref) D: age; SE: educational level; BM: hypertension; HB: smoking; R: - Cut-off for youngest group <27
≥ 27 63 (51.0) 102 (41.2)   1.45 (0.9–2.3)
Bertuccio
2007 [24]
< 20 58 (11.4) 73 (8.6) 1 (ref) 1 (ref) D: age, study; SE: education; BM: BMI, Cholesterol, DM, obesity, HLD, HT; HB: Smoking, coffee, alcohol; R: parity, MP, HRT, family history AMI Extensive adjustment in final model
20–24 207 (40.7) 342 (40.1) 0.72 (0.5–1.1) 0.90 (0.6–1.4)
25–29 172 (33.9) 319 (37.4) 0.65 (0.4–0.97) 0.92 (0.6–1.5)
≥ 30 71 (14.0) 118 (13.9) 0.70 (0.4–1.1) 0.94 (0.6–1.6)
  1. D demographics, SE Socio-economic, BM Biomedical, HB Health behavior, R Reproductive, HT hypertension, DM diabetes mellitus, MI myocardial infarction, AMI acute myocardial infraction, BMI body mass index, HLD hyperlipidemia, MP menopause, HRT hormone replacement therapy
  2. aRisk estimates used: Relative risk: Beard, La Vecchia, Talbot, Palmer. Odds ratio: Okamoto, Bertuccio
  3. bAnalysis with 25+ and never pregnant separately showed the same risk for those two groups, which is why the authors combined them
  4. cAuthors indicate that a multivariate model yielded the same/similar results
  5. The bold data indicate significant results