Table 2.
Socioeconomic background of the women recruited to the ALSPAC
| Characteristic | Recruited mothers (n = 14 541) | Mothers who completed FFQ about the child at age 3 years (n = 10 137) | Mothers who completed food record for child at age 7 years (n = 7285) | Mothers who completed FFQ about the child at age 13 years (n = 6173) | |||
|---|---|---|---|---|---|---|---|
| n (%) | n (%) | P-valuea | n (%) | P-valueb | n (%) | P-valuec | |
| Maternal educational attainment | <0.001 | <0.001 | <0.001 | ||||
| No academic qualifications at age 16 y | 3709 (25.5) | 2519 (24.9) | 1390 (19.1) | 1167 (18.9) | |||
| Academic qualification at age 16 y | 4273 (29.4) | 3479 (34.3) | 2384 (32.7) | 1989 (32.2) | |||
| Education beyond age 16 y | 4358 (30.0) | 3786 (37.3) | 2907 (39.9) | 2607 (42.3) | |||
| Missing | 2201 (15.1) | 353 (3.5) | 604 (8.3) | 410 (6.6) | |||
| Maternal age at birth (years) | <0.001 | <0.001 | <0.001 | ||||
| <20 | 655 (4.5) | 284 (2.8) | 112 (1.5) | 111 (1.8) | |||
| 20–24 | 2682 (18.4) | 1577 (15.6) | 911 (12.5) | 732 (11.9) | |||
| 25–29 | 5369 (36.9) | 4039 (39.8) | 2718 (37.3) | 2281 (36.9) | |||
| 30–34 | 3808 (26.2) | 3130 (30.9) | 2299 (31.5) | 2040 (33.0) | |||
| ≥35 | 1382 (9.5) | 1107 (10.9) | 862 (11.9) | 744 (12.1) | |||
| Missing | 645 (4.5) | 0 | 383 (5.3) | 265 (4.3) | |||
| Housing tenure | <0.001 | <0.001 | <0.001 | ||||
| Mortgaged or owned | 9757 (67.1) | 7775 (76.7) | 5641 (77.4) | 4850 (78.5) | |||
| Council and housing association rented | 2138 (14.7) | 1177 (11.6) | 584 (8.0) | 464 (7.5) | |||
| Privately rented or other | 1440 (9.9) | 882 (8.7) | 492 (6.8) | 448 (7.3) | |||
| Missing | 1206 (8.3) | 303 (3.0) | 568 (7.8) | 411 (6.7) | |||
| Ethnicity | <0.001 | <0.001 | <0.001 | ||||
| White | 11 927 (82.0) | 9555 (94.3) | 6549 (89.9) | 5654 (91.6) | |||
| Other ethnic groups | 321 (2.2) | 194 (2.0) | 112 (1.5) | 95 (1.5) | |||
| Missing | 2293 (15.8) | 388 (3.7) | 624 (8.6) | 424 (6.9) | |||
| Smoked in last trimester of pregnancy | <0.001 | <0.001 | <0.001 | ||||
| Yes | 2413 (16.6) | 1644 (16.3) | 897 (12.3) | 721 (11.7) | |||
| No | 8859 (60.9) | 7343 (72.4) | 5254 (72.1) | 4593 (74.4) | |||
| Missing | 3269 (22.5) | 1150 (11.3) | 1134 (15.6) | 859 (13.9) | |||
| Maternal prepregnancy BMI | <0.001 | <0.001 | <0.001 | ||||
| <18.5 | 567 (4.0) | 426 (4.2) | 259 (3.6) | 259 (4.2) | |||
| 18.5–24.99 | 8564 (58.9) | 6817 (67.2) | 4761 (65.4) | 4162 (67.4) | |||
| 25–29.99 | 1737 (12.0) | 1388 (13.7) | 924 (12.7) | 763 (12.4) | |||
| ≥30 | 631 (4.3) | 491 (4.8) | 317 (4.4) | 264 (4.3) | |||
| Missing | 3033 (20.8) | 1015 (10.0) | 1024 (14.1) | 725 (11.7) | |||
a t-test comparing women in the original cohort (n = 14 541) with those who completed the food frequency questionnaire for their child at age 3 years (n = 10 137)
b t-test comparing women in the original cohort (n = 14 541) with those who completed the food record for their child at age 7 years (n = 7285)
c t-test comparing women in the original cohort (n = 14 541) with those who completed the food frequency questionnaire for their child aged 13 years (n = 6173)
Abbreviations: BMI, body mass index; FFQ, food frequency questionnaire.