Table 1 Characteristics of the study population by breastfeeding status

From: The association between being breastfed in infancy and risks of cancer in adulthood—a UK Biobank study

Characteristic

Breastfeeding data available (n = 339,115)

Breastfed (n = 247,397)

Not breastfed (n = 91,718)

Female sex, n (%)

135,060 (54.6%)

56,057 (61.1%)

Ethnicity, n (%)

 White

227,406 (92.0%)

89,389 (97%)

 Asian

7500 (3.0%)

578 (0.6%)

 Black

5960 (2.4%)

297 (0.3%)

 Mixed

1453 (0.6%)

578 (0.6%)

 Other

4130 (1.7%)

655 (0.7%)

 Missing

948 (0.4%)

221 (0.2%)

Early life factors

Year of birth category

 <1945

63,742 (25.8%)

14,538 (15.9%)

 1945–1949

58,972 (23.8%)

16,607 (18.1%)

 1950–1954

44,830 (18.1%)

14,977 (16.3%)

 1954–1959

37,567 (15.2%)

16,590 (18.1%)

 ≥1960

42,286 (17.1%)

29,006 (31.6%)

Birthweight in grams, n (%)

 ≤2750

19,897 (8.0%)

12,181 (13.3%)

 >2750–3250

44,768 (18.1%)

19,274 (21.0%)

 >3250–3750

55,118 (22.3%)

21,300 (23.2%)

 >3750–4250

22,352 (9.0%)

8254 (9.0%)

 >4250–4750

8938 (3.6%)

3218 (3.5%)

 >4750

2709 (1.1%)

873 (1.0%)

 Missing

93,615 (37.8%)

26,618 (29.0%)

Mother smoked (%)

 Yes

56,249 (22.7%)

29,510 (32.2%)

 No

167,017 (67.5%)

53,198 (58%)

 Missing

24,131 (9.8%)

9010 (9.8%)

Relative size at age 10, n (%)

 Thinner

79,644 (32.2%)

30,406 (33.2%)

 About Average

125,900 (50.9%)

43,826 (47.8%)

 Larger

37,956 (15.3%)

16,258 (17.7%)

 Missing

3897 (1.6%)

1228 (1.3%)

Characteristics at recruitment

 Age at recruitment (median (IQR)

58 (50, 63)

53 (46, 60)

 Townsend deprivation score, median (IQR)*a

−2.17 (−3.67 –0.46)

−2.08 (−3.61 −0.63)

Education, n (%)

 High

116,969 (47.3%)

38,630 (42.2%)

 Intermediate

91,047 (36.8%)

38,036 (41.5%)

 Low

35,177 (14.2%)

13,652 (14.9%)

 Missing

4204 (1.7%)

1400 (1.5%)

Smoking status, n (%)

 Never-smoked

137,018 (55.4%)

52,886 (57.7%)

 Ex-smoker

85,071 (34.4%)

28,312 (30.9%)

 Current smoker

24,478 (9.9%)

10,269 (11.2%)

 Missing

830 (0.3%)

251 (0.3%)

Body mass index, kg/m2 (median, (IQR))*b

26.7 (24.1–29.8)

26.6 (24.0–29.9)

Hormone replacement therapy*c

 Yes

50,676 (37.5%

17,406 (31.1%)

 No

83,834 (62.1%)

38,487 (68.7%)

 Missing

550 (0.4%)

164 (0.2%)

  1. IQR interquartile range. Where participant data were entirely missing or the participant answered, “Do not know” or “Prefer not to answer”, data were recoded as “Missing”.
  2. *aA total of 434 individuals had missing Townsend deprivation score data. The more negative the deprivation score the less socioeconomically deprived the participant is.
  3. *b1771 participants had missing body mass index data.
  4. *cHormone replacement therapy was only assessed in female participants.
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