Table 1.

Characteristics of female participants in the Reykjavik Study according to location of first residence, Iceland, 1967–2013

Location of first residence
Reykjavik areaCoastal villageRural area
(n = 3,474)(n = 3,262)(n = 2,604)Pa
Duration of first residence
 Mean (SD)44.7(15.3)20.6(11.5)19.0(7.8)0.001
Age at study entryb
 Mean (SD)52.8(9.6)54.2(9.7)54.9(10.2)0.001
Age at diagnosis
 Mean (SD)68.6(10.8)70.5(10.7)70.4(11.4)0.078
Height (cm)e
 Mean (SD)163.7(5.7)162.6(5.7)162.5(5.6)0.001
BMI (kg/m2)e
 Mean (SD)25.1(4.3)25.2(4.3)25.1(4.2)0.903
Education, n (%)
Birth cohort, n (%)
Children, n (%)
 3 or more2200(64)2004(62)1421(55)
Regular physical activity, n (%)
Age at menarchec, n (%)
 ≤13 y1543(44)1249(38)1137(44)0.001
 ≥14 y1603(46)1680(52)1195(46)
 Missing values328(9)333(10)272(10)
Age of birth of first childc, n (%)
 ≤24 y1904(55)1684(52)1014(39)0.001
 ≥25 y1016(29)1003(31)1049(40)
 Missing values250(7.2)239(7.3)194(7.5)
Ever use HRTc,e, n (%)
Ever use oral contraceptive, nc, e
Total months of breastfeedingc,e, n (%)
 1–6 months787(23)725(22)496(19)
 ≥7 months1525(44)1387(43)1099(42)
Fish consumption in adolescenced (n = 2,898), n (%)
 ≤2 portions p/w594(52)448(45)397(51)0.001
 >2 up to 4 portions p/w105(9)78(8)128(17)
 >4 portions p/w441(39)463(47)244(32)
Meat consumption in adolescenced (n = 2,881), n (%)
 2 times or less p/w372(33)277(28)307(40)0.001
 3–4 times p/w744(66)688(70)389(51)
 5 times p/w or more17(2)17(2)70(9)
Milk consumption in adolescenced (n = 2.886), n (%)
 Less than daily304(27)283(29)125(16)0.001
 Daily or more833(73)700(71)641(84)
  • Abbreviation: HRT, hormone replacement therapy.

  • aP values are based on χ2 tests, except for length of residence, age at entry, age at diagnosis, height and BMI, where one-way ANOVA test was used.

  • bParticipants underwent the first clinical examination (first visit) between 1967 and 1996.

  • cInformation retrieved from the CDC cohort.

  • dData were available only for women who entered the AGES-Reykjavik Study in 2002–2006.

  • eValues were missing for 36 women on height; 88 women on BMI; 2,471 women on use of HRT; 2,422 women on use of oral contraceptive; 2,281 women on breastfeeding.