Table 1 Description of study sample of 2444 adults

From: Modification of genetic influences on adiposity between 36 and 63 years of age by physical activity and smoking in the 1946 British Birth Cohort Study

 

36 Years

43 Years

53 Years

60–64 Years

Exact age (years), median (range)

36.3 (36.0, 37.2)

43.5 (42.8, 44.3)

53.5 (53.0, 54.2)

63.3 (59.8, 64.9)

BMI (kg m − 2 ), mean (s.d.)

24.1 (3.5)

25.4 (4.0)

27.4 (4.6)

28.0 (4.9)

 Normal weighta, N (%) (valid %)b

1457 (59.6) (66.0)

1203 (49.2) (52.5)

793 (32.5) (32.7)

501 (20.5) (28.3)

 Overweighta, N (%) (valid %)b

629 (25.7) (28.5)

825 (33.8) (36.0)

1071 (43.8) (44.1)

756 (30.9) (42.7)

 Obesea, N (%) (valid %)b

123 (5.0) (5.6)

264 (10.8) (11.5)

564 (23.1) (23.2)

514 (21.0) (29.0)

 Missing, N (%)

235 (9.6)

152 (6.2)

16 (0.7)

673 (27.5)

WHtR, mean (s.d.)

0.49 (0.06)

0.50 (0.07)

0.54 (0.07)

0.58 (0.07)

 No central obesityc, N (%) (valid %)b

1295 (53.0) (58.5)

1207 (49.4) (52.8)

660 (27.0) (27.1)

249 (10.2) (14.1)

 Central obesityc, N (%) (valid %)b

917 (37.5) (41.5)

1079 (44.1) (47.2)

1772 (72.5) (72.9)

1517 (62.1) (85.9)

 Missing, N (%)

232 (9.5)

158 (6.5)

12 (0.5)

678 (27.7)

PA d

 Inactive, N (%) (valid %)b

804 (32.9) (36.2)

1191 (48.7) (51.5)

1189 (48.6) (48.7)

1138 (46.6) (65.3)

 Active, N (%) (valid %)b

1414 (57.9) (63.8)

1120 (45.8) (48.5)

1253 (51.3) (51.3)

606 (24.8) (34.7)

 Missing, N (%)

226 (9.2)

133 (5.4)

2 (0.1)

700 (28.6)

SM d

    

 Smoker, N (%) (valid %)b

719 (29.4) (32.3)

665 (27.2) (28.9)

595 (24.3) (24.3)

237 (9.7) (12.7)

 Non-smoker, N (%) (valid %)b

1505 (61.6) (67.7)

1640 (67.1) (71.1)

1848 (75.6) (75.6)

1636 (66.9) (87.3)

 Missing, N (%)

220 (9.0)

139 (5.7)

1 (0.0)

571 (23.4)

PA/SM d

 Inactive/smoker, N (%) (valid %)b

301 (12.3) (13.6)

425 (17.4) (18.4)

386 (15.8) (15.8)

157 (6.4) (9.7)

 Active/smoker, N (%) (valid %)b

415 (17.0) (18.7)

240 (9.8) (10.4)

209 (8.6) (8.6)

35 (1.4) (2.2)

 Inactive/non-smoker, N (%) (valid %)b

503 (20.6) (22.7)

762 (31.2) (33.1)

803 (32.9) (32.9)

889 (36.6) (55.0)

 Active/non-smoker, N (%) (valid %)b

998 (40.8) (45.0)

878 (35.9) (38.1)

1044 (42.7) (42.8)

534 (21.8) (33.1)

 Missing, N (%)

227 (9.3)

139 (5.7)

2 (0.1)

829 (33.9)

  1. Abbreviations: BMI, body mass index; PA, physical activity; SM, smoking; WHtR, waist circumference-to-height ratio.
  2. aNormal weight: BMI <25 kg m−2; overweight: BMI ⩾25 kg m−2, but <30 kg m−2; obese: BMI ⩾30 kg m−2.
  3. bValid % excludes missing data and is calculated as the N in that cell divided by the N who had data for that particular variable at that particular age multiplied by 100.
  4. cNo central obesity: WHtR <0.5; central obesity: WHtR ⩾0.5.
  5. Participation in leisure time PA and smoking status were ascertained at each age during an interview with a research nurse. Participants were categorised as being a ‘smoker’ if they currently smoked or a ‘non-smoker’ if they had never smoked or were an ex-smoker. Leisure time PA assessment was based on the Minnesota leisure time PA questionnaire at 36 years of age and on more basic questions at 43, 53 and 60–64 years of age. At each age, participants who reported no leisure time physical activity were classified as ‘inactive’ and those who reported any relevant activity (in the previous month at 36 years of age, in the previous year at 43 years of age and in the previous 4 weeks at 53 and 60–64 years of age) were classified as ‘active’.
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