Table 2 OR and its 95 % CI of some potential risk factors and confounders of obesity in preschool children using univariate conditional logistic regression

Intrauterine and perinatal factors

Birth weight

<2500, 2500–4000 (ref.), ≧4000

1846

3176

2500–4000

1556

1

-

2658

1

-

<2500

31

1.060 (0.508–2.212)

0.8770

52

0.994 (0.575–1.717)

0.9815

≧4000

259

1.876 (1.427–2.467)

<0.0001

466

1.880 (1.525–2.319)

<0.0001

Gestational age

<37, 37–42 (ref.), ≧42

1804

3244

37–42

1644

1

-

2956

1

-

<37

85

1.113 (0.715–1.734)

0.6354

134

1.214 (0.853–1.730)

0.2820

≧42

75

1.642 (1.016–2.654)

0.0436

154

1.117 (0.807–1.546)

0.5030

No of fetuses

1 (ref.), 2 (twins)

-

-

-

3252

0.889 (0.513–1.541)

0.6750

Mode of delivery

Caesarean, vaginal (ref.)

-

-

-

3234

1.381 (1.195–1.595)

<0.0001

Gestational diabetes

No (ref.), yes

1788

0.801 (0.316–2.029)

0.6374

3192

1.647 (0.902–3.009)

0.1011

Gestational hypertension

No (ref.), yes

1798

1.838 (1.231–2.743)

0.0025

3200

2.392 (1.539–3.717)

<0.0001

Feeding patterns in the first 4 months^a

Breast feeding, formula/milk (ref.)

1846

0.917 (0.731–1.150)

0.4522

3200

0.834 (0.713–0.976)

0.0234

Dietary habit

Appetite

Good, average (ref.), bad

1826

3236

Average

447

1

-

1102

1

-

Good

1335

14.326 (9.651–21.266)

<0.0001

2074

10.995 (8.622–14.02)

<0.0001

Bad

44

0.519 (0.143–1.883)

0.3123

60

0.209 (0.072–0.602)

0.0038

Eating speed^b

Fast, average (ref.), slow

1820

3224

Average

1126

1

-

1674

1

-

Fast

444

8.282 (5.739–11.952)

<0.0001

947

7.404 (5.763–9.511)

<0.0001

Slow

250

0.136 (0.083–0.222)

<0.0001

603

0.227 (0.171–0.302)

<0.0001

Snack

Not at all, occasional, often

1808

1.164 (1.008–1.343)

0.0380

3208

0.948 (0.861–1.044)

0.2789

Vegetable intake

Not at all, occasional, often

1762

0.849 (0.720–1.003)

0.0532

3236

0.869 (0.766–0.986)

0.0292

Behavior and lifestyle

Activity preferred

Outdoor play, TV viewing (ref.), indoor game

1194

-

TV viewing

484

1

-

-

-

-

Outdoor play

479

0.596 (0.446–0.795)

<0.0004

-

-

-

Indoor game

231

0.876 (0.629–1.221)

0.4337

-

-

-

Daily time for outdoor activity

Time (hr):≧2

-

3232

<half

-

-

-

367

1

-

Half-1

-

-

-

1143

0.955 (0.753–1.212)

0.5286

1-2

-

-

-

1126

0.845 (0.729–0.979)

0.0247

≧2

-

-

-

596

1.019 (0.773–1.343)

0.8923

Type/intensity of outdoor activity^c

Running or jumping, walking or cycling, slow walking or sitting (ref.)

1212

3146

slow walking or sitting

148

1

-

808

1

-

Running or jumping

659

0.757 (0.588–0.974)

0.0302

2000

0.725 (0.609–0.863)

<0.0001

Walking or cycling

405

0.674 (0.351–1.294)

0.1275

338

1.130 (0.869–1.469)

0.3601

Daily time for TV viewing^d

Time (hr):≧2

-

3184

<half

-

-

-

447

1

-

Half-1

-

-

-

1164

1.224 (0.978–1.532)

0.0776

1–2

-

-

-

1117

1.373 (1.171–1.610)

<0.0001

≧2

-

-

-

456

1.996 (1.602–2.487)

<0.0001

Daily sleep time.

Unit 0.5 h

1806

0.935 (0.894–0.978)

0.0033

3198

0.942 (0.906–0.981)

0.0035

Night sleep time

Unit 0.5 h

-

-

-

3198

0.890 (0.846–0.936)

<0.0001

Parents and family-related factors

Family type^e

Nuclear family (ref.), extended, single-parent

-

3242

Nuclear family

-

-

-

1788

1

-

Extended

-

-

-

1401

1.241 (1.075–1.433)

0.0021

Single-parent

-

-

-

53

0.756 (0.426–1.341)

0.3372

Raising kids mainly by

Parents (ref.), grandparents, or nannies/nursery

1622

3250

Parents

1035

1

-

2427

1

-

Grandparents

399

1.277 (1.010–1.614)

0.0016

702

1.408 (1.181–1.678)

0.0002

Nannies/nursery

188

0.606 (0.287–1.279)

0.1842

121

1.308 (0.779–2.194)

0.0818

Mother education

College and over, high school and below (ref.)

1794

0.851 (0.667–1.086)

0.1936

3242

0.731 (0.625–0.855)

<0.0001

Father education

College and over, high school and below (ref.)

1798

0.674 (0.521–0.871)

0.0025

3222

0.675 (0.575–0.791)

<0.0001

Family income in local

Upper, middle (ref.), lower

1828

3130

Middle

1559

1

-

2968

1

-

Upper

232

1.040 (0.772–1.402)

0.7955

85

1.546 (0.967–2.473)

0.0668

Lower

37

1.317 (0.687–2.524)

0.4111

77

1.948 (1.223–3.103)

0.0049

Family income per month

RMB:<1500, 1500–10,000 (ref.), ≧10,000

-

3100

1500–10,000

-

-

-

2683

1

-

<1500

-

-

-

189

1.435 (1.042–1.977)

0.0260

≧10,000

-

-

-

228

1.430 (1.076–1.901)

0.0152

Father BMI^f

<24 (ref.), ≧24

1804

2.525 (2.041–3.125)

<0.0001

3152

2.164 (1.866–2.510)

<0.0001

Mother BMI^f

<24 (ref.), ≧24

1790

4.031 (3.072–5.288)

<0.0001

3192

2.538 (2.075–3.104)

<0.0001

Mother family history of obesity^g

No (ref.), yes

1826

2.644 (2.110–3.313)

<0.0001

-

-

-

Father family history of obesity^g

No (ref.), yes

1816

2.640 (2.122–3.284)

<0.0001

-

-

-