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. Author manuscript; available in PMC: 2022 May 12.
Published in final edited form as: Eur J Clin Nutr. 2021 Nov 12;76(5):671–679. doi: 10.1038/s41430-021-01031-z

Table 1. Distribution of sociodemographic factors in the study population in each survey year.

  Survey years
1985 1990 1995 2000 2005 2010
Population (a) 3,552 3,633 3,178 2,792 4,768 7,396
Age when giving birth N (b) % (c) N % N % N % N % N %
Under 20 193 (4.8) 143 (3.4) 111 (3.3) 108 (4) 152 (4) 137 (3)
20-24 914 (25.3) 739 (19.6) 461 (14.1) 367 (13.4) 640 (15.2) 792 (13.9)
25-29 1,350 (38.3) 1,410 (38.9) 1,082 (34.7) 748 (26.6) 1,143 (26.3) 2,027 (28.5)
30 or over 1,086 (31.6) 1,331 (38.1) 1,519 (47.9) 1,560 (56.1) 2,818 (54.5) 4,413 (54.5)
Missing 9 0.3 10 0.3 5 0.2 9 0.3 15 0.3 27 0.4
Education - age when completed full-time education
16 or under (Least number of years of full-time education) 1,676 (47.1) 1,448 (40.3) 982 (31.8) 707 (25.6) 886 (19.2) 872 (13.3)
17 or 18 1,099 (31.6) 1,303 (36.8) 1,178 (38) 913 (33.9) 1,451 (31.5) 1,745 (25.4)
Over 18 (Higher education) 755 (21.4) 853 (23) 994 (30.2) 1,156 (40.4) 2,392 (49.4) 4,702 (61.3)
Missing 22 0.6 29 0.8 24 0.8 16 0.6 39 0.8 77 1.0
Socioeconomic status based on partner’s occupation (SOC)
Managerial and professional 301 (8.9) 392 (11.3) 331 (9.8) - - - - - -
Intermediate 876 (26.5) 875 (25.9) 941 (31.8) - - - - - -
Skilled, Non-manual 344 (10.1) 315 (9.3) 260 (9) - - - - - -
Skilled, Manual 1,018 (30.2) 923 (27.2) 670 (22.9) - - - - - -
Semi-skilled 414 (12.2) 385 (10.7) 270 (8.7) - - - - - -
Unskilled 172 (3.2) 70 (1.3) 109 (2.4) - - - - - -
Unclassified 409 (9.1) 655 (14.2) 578 (15.4) - - - - - -
Missing 18 0.5 18 0.5 19 0.6 - - - - - -
Socioeconomic status based on mother's occupation (NS-SEC)
Managerial and professional - - - - - - 1,059.0 (37.2) 2,187.0 (44.3) 3,315.0 (40.4)
Intermediate - - - - - - 590.0 (22.3) 973.0 (20.1) 1,402.0 (19)
Routine and manual - - - - - - 579.0 (20.4) 1,172.0 (25.4) 1,624.0 (23.5)
Never worked - - - - - - 300.0 (11.1) 282.0 (7) 515.0 (9.3)
Unclassified - - - - - - 264.0 (9) 154.0 (3.2) 540.0 (7.9)
Employment status at six weeks after birth
Paid maternity leave 240 (7.2) 880 (25.7) 1,254 (40.9) 1,317 (46.5) 2,834 (58.3) 4,597 (59.4)
Unpaid maternity leave 311 (8.9) 241 (6.4) 219 (6.5) 123 (4.1) 169 (3.6) 301 (4.2)
Doing paid work 186 (5.4) 257 (7.7) 225 (6.5) 172 (6.2) 139 (2.4) 394 (5.1)
Not doing paid work 2,797 (78.5) 2,245 (60.2) 1,470 (46.1) 1,172 (43.3) 1,601 (35.7) 2,036 (31.3)
Missing 18 0.5 10 0.3 10 0.3 8 0.3 25 0.5 68 0.9
Ethnicity
White - - - - - - 6,747 (93.1) 3,904 (80.6) 5,976 (79.6)
Black, Asian, Mixed, Multiple or other - - - - - - 415 (6.9) 813 (19.4) 1,131 (20.4)
Missing - - - - - - 206 2.8 51 1.1 289 3.9
Partnership status
Married 3,020 (87.5) 2,859 (81.2) 2,315 (74) 1,824 (66.6) 2,994 (64.7) 4,937 (64.8)
Living with a partner 240 (6.6) 383 (10.6) 494 (16.2) 620 (22.7) 1,097 (23.6) 1,773 (25)
Single 273 (5.9) 373 (8.2) 350 (9.8) 329 (10.6) 603 (11.8) 613 (10.2)
Missing 19 0.5 18 0.5 19 0.6 19 0.7 74 1.6 73 1.0

Notes:

(a)

Total unweighted population of mothers analysed for breastfeeding at six weeks in each survey

(b)

Number of mothers in each sociodemographic sub-group category, unweighted

(c)

Weighted proportion of mothers in each sociodemographic sub-group category Dash (–) = factor not assessed by the IFS in that survey year