Table 2.
Associations between 21 risk factors and obesity at age 7 years in cohort of Avon longitudinal study of parents and children. Values are percentages (numbers) unless stated otherwise
| Risk factors | Prevalence of childhood obesity (n=7758) | Unadjusted (univariable) odds ratio (95% Cl) | P value | Final model adjusted odds ratio (95% Cl)†(n=5493) | P value |
|---|---|---|---|---|---|
| Intrauterine and perinatal factors | |||||
| Birth weight, continuous* (100 g units) | 8.4 (605/7224) | 1.05 (1.03 to 1.07) | <0.001 | 1.05 (1.03 to 1.07) | <0.001 |
| Missing data | 12.3 (66/534) | — | — | — | — |
| Sex* | |||||
| Male
|
9.2 (362/3934)
|
1.00
|
0.079 | 1.00
|
0.890 |
| Female | 8.1 (309/3824) | 0.87 (0.74 to 1.02) | 0.99 (0.81 to 1.21) | ||
| Missing data | — | — | — | — | — |
| Parity* | |||||
| 0
|
8.3 (265/3205)
|
1.00
|
0.854 | Did not enter | — |
| 1
|
8.4 (215/2557)
|
1.02 (0.84 to 1.23)
|
|||
| ≥2 | 7.9 (103/1308) | 0.95 (0.75 to 1.20) | |||
| Missing data | 12.8 (88/688) | — | — | — | — |
| Maternal smoking during pregnancy per day* | |||||
| None
|
7.5 (443/5889)
|
1.00
|
<0.001 | 1.00
|
<0.010 |
| 1-9
|
11.5 (50/434)
|
1.60 (1.17 to 2.18)
|
1.76 (1.21 to 2.52)
|
||
| 10-19
|
11.3 (48/423)
|
1.57 (1.15 to 2.16)
|
1.59 (1.08 to 2.34)
|
||
| ≥20 | 13.8 (19/138) | 1.96 (1.20 to 3.22) | 1.80 (1.01 to 3.39) | ||
| Missing data | 12.7 (111/874) | — | — | — | — |
| Season of birth* | |||||
| Jan-Mar
|
8.7 (106/1219)
|
1.00
|
0.884 | Did not enter | — |
| Apr-Jun
|
8.0 (167/2080)
|
0.92 (0.71 to 1.18)
|
|||
| Jul-Sep
|
8.2 (160/1949)
|
0.94 (0.73 to 1.21)
|
|||
| Oct-Dec | 8.6 (177/2065) | 0.98 (0.77 to 1.27) | |||
| Missing data | 13.7 (61/445) | — | — | — | — |
| Gestational age (weeks) | |||||
| <37
|
8.4 (31/412)
|
1.00
|
0.436 | Did not enter | — |
| 37-42
|
8.4 (574/6864)
|
1.12 (0.87 to 1.45)
|
|||
| >42 | 13.5 (5/37) | 1.75 (0.68 to 4.50) | |||
| Missing data | 13.7 (61/445) | — | — | — | — |
| No of fetuses | |||||
| 1
|
8.7 (655/7551)
|
1.00
|
0.635 | Did not enter | — |
| 2 | 7.7 (16/207) | 0.88 (0.53 to 1.48) | |||
| Infant feeding | |||||
| Breast feeding* | |||||
| Exclusive at 2 months
|
6.9 (152/2211)
|
0.64 (0.50 to 0.82)
|
0.002 | 1.22 (0.87 to 1.71)
|
0.464 |
| Stopped or non-exclusive
|
8.5 (281/3287)
|
0.81 (0.64 to 1.01)
|
1.08 (0.80 to 1.45)
|
||
| Never | 10.4 (120/1153) | 1.00 | 1.00 | ||
| Missing data | 10.7 (118/1107) | — | — | — | — |
| Introduction of solids (months)* | |||||
| <1
|
9.6 (17/177)
|
1.44 (0.85 to 2.45)
|
0.003 | 0.88 (0.42 to 1.87)
|
0.296 |
| 1 or 2
|
10.6 (12/113)
|
1.61 (0.83 to 3.01)
|
1.08 (0.50 to 2.32)
|
||
| 2 or 3
|
11.6 (77/664)
|
1.78 (1.33 to 2.39)
|
1.48 (1.01 to 2.16)
|
||
| 3 or 4
|
8.3 (320/3868)
|
1.22 (0.99 to 1.51)
|
1.08 (0.83 to 1.39)
|
||
| 4-6 | 6.9 (134/1953) | 1.00 | 1.00 | ||
| Missing data | 11.3 (111/983) | — | — | — | — |
| Family characteristics | |||||
| Parental obesity (body mass index)* | |||||
| Both parents (<30)
|
6.2 (264/4253)
|
1.00
|
<0.001 | 1.00
|
<0.001 |
| Father (>30)
|
16.2 (49/302)
|
2.93 (2.10 to 4.07)
|
2.54 (1.72 to 3.75)
|
||
| Mother (>30)
|
23.6 (46/195)
|
4.66 (3.28 to 6.64)
|
4.25 (2.86 to 6.32)
|
||
| Both parents obese
|
43.8 (21/48)
|
11.75 (6.55 to 21.06)
|
10.44 (5.11 to 21.32)
|
||
| Missing data | 9.8 (291/2960) | 1.65 (1.38 to 1.96) | 1.33 (1.06 to 1.67) | ||
| No of siblings* | |||||
| None
|
8.8 (251/2858)
|
1.31 (0.81 to 2.13)
|
0.304 | Did not enter | — |
| 1
|
7.5 (196/2604)
|
1.11 (0.69 to 1.81)
|
|||
| 2
|
8.5 (80/944)
|
1.26 (0.75 to 2.12)
|
|||
| ≥3 (1) | 6.8 (19/278) | 1.00 | |||
| Missing data | 11.6 (125/1074) | — | — | — | — |
| Ethnicity of child: | |||||
| White
|
8.0 (535/6647)
|
1.00
|
0.156 | Did not enter | — |
| Non-white | 10.5 (29/277) | 1.34 (0.90 to 1.98) | |||
| Missing data | 12.8 (107/834) | — | — | — | — |
| Age of mother at delivery: | |||||
| <20
|
7.4 (10/135)
|
0.91 (0.47 to 1.73)
|
0.204 | Did not enter | — |
| 20-24
|
9.8 (98/998)
|
1.23 (0.98 to 1.55)
|
|||
| ≥25 | 8.1 (502/6180) | 1.00 | |||
| Missing data | 13.7 (61/445) | — | — | — | — |
| Lifestyle factors in childhood | |||||
| Time spent watching television per week (hours)*: | |||||
| ≤4
|
5.2 (75/1450)
|
1.00
|
<0.001 | 1.00
|
<0.010 |
| 4.1-8
|
8.3 (252/3026)
|
1.66 (1.28 to 2.17)
|
1.37 (1.02 to 1.83)
|
||
| >8 | 10.3 (201/1950) | 2.10 (1.60 to 2.77) | 1.55 (1.13 to 2.12) | ||
| Missing data | 10.7 (143/1332) | — | — | — | — |
| Time in car per day | |||||
| Weekdays (hours): | |||||
| None
|
6.9 (37/533)
|
1.00
|
0.34 | Did not enter | — |
| <1
|
8.1 (426/5227)
|
1.19 (0.84 to 1.69)
|
|||
| ≥1 | 9.2 (67/725) | 1.37 (0.90 to 2.07) | |||
| Missing data | 11.1 (141/1273) | — | — | — | — |
| Weekend (hours): | |||||
| None
|
12.3 (26/211)
|
1.00
|
0.090 | Did not enter | |
| <1
|
8.0 (346/4332)
|
0.62 (0.40 to 0.95)
|
|||
| ≥1 | 8.2 (157/1907) | 0.64 (0.41 to 0.99) | |||
| Missing data | 10.9 (142/1308) | — | — | — | — |
| Duration of night time sleep (hours)* | |||||
| First quarter (<10.5)
|
10.3 (171/1660)
|
1.57 (1.23 to 1.99)
|
<0.001 | 1.45 (1.10 to 1.89)
|
<0.010 |
| Second quarter (10.5-10.9)
|
8.8 (135/1539)
|
1.31 (1.02 to 1.69)
|
1.35 (1.02 to 1.79)
|
||
| Third quarter (11-11.9)
|
6.4 (87/1351)
|
0.94 (0.71 to 1.25)
|
1.04 (0.76 to 1.42)
|
||
| Fourth quarter (>12) | 6.8 (128/1876) | 1.00 | 1.00 | ||
| Missing data | 11.3 (150/1322) | — | — | — | — |
| Dietary patterns | |||||
| Food group 1 (junk)*: | |||||
| First quarter
|
5.5 (89/1607)
|
1.00
|
<0.001 | 1.00
|
0.083 |
| Second quarter
|
7.9 (127/1606)
|
1.46 (1.11 to 1.94)
|
1.43 (1.00 to 1.85)
|
||
| Third quarter
|
10.1 (162/1607)
|
1.91 (1.46 to 2.50)
|
1.48 (1.08 to 2.02)
|
||
| Fourth quarter | 9.2 (148/1607) | 1.73 (1.32 to 2.27) | 1.24 (0.87 to 1.76) | ||
| Missing data | 10.9 (145/1331) | — | — | — | — |
| Food group 2 (healthy)*: | |||||
| First quarter
|
9.2 (148/1607)
|
1.00
|
0.061 | 1.00
|
0.769 |
| Second quarter
|
8.5 (136/1609)
|
0.91 (0.71 to 1.16)
|
1.01 (0.76 to 1.34)
|
||
| Third quarter
|
8.4 (135/1607)
|
0.90 (0.71 to 1.15)
|
1.02 (0.75 to 1.37)
|
||
| Fourth quarter | 6.7 (107/1605) | 0.70 (0.54 to 0.91) | 0.87 (0.61 to 1.22) | ||
| Missing data | 10.9 (145/1331) | — | — | — | — |
| Food group 3 (traditional)*: | |||||
| First quarter
|
7.6 (122/1608)
|
1.00
|
0.088 | 1.00
|
0.386 |
| Second quarter
|
8.3 (133/1612)
|
1.10 (0.85 to 1.42)
|
1.13 (0.84 to 1.53)
|
||
| Third quarter
|
7.3 (117/1607)
|
0.96 (0.74 to 1.25)
|
1.01 (0.74 to 1.38)
|
||
| Fourth quarter | 9.6 (154/1601) | 1.30 (1.01 to 1.66) | 1.26 (0.92 to 1.72) | ||
| Missing data | 10.9 (145/1331) | — | — | — | — |
| Food group 4 (fussy)*: | |||||
| First quarter
|
9.9 (159/1606)
|
1.00
|
0.005 | 1.00
|
0.635 |
| Second quarter
|
8.7 (139/1606)
|
0.86 (0.68 to 1.10)
|
0.95 (0.71 to 1.27)
|
||
| Third quarter
|
7.6 (122/1609)
|
0.75 (0.58 to 0.96)
|
0.92 (0.67 to 1.27)
|
||
| Fourth quarter | 6.6 (106/1607) | 0.64 (0.50 to 0.83) | 0.79 (0.55 to 1.14) | ||
| Missing data | 10.9 (145/1331) | — | — | — | — |
*
Effect of variable on obesity at age 7 years is independent of maternal education.
†
Odds ratio (95% CI) also adjusted for maternal education, energy intake at age 3 years (food groups), and sex. Variables significant (P<0.01) at within group analysis entered into final model (data from within group analyses not shown).