Table 1 Linear regressions of factors associated with the baby’s parameters at birth according to the Fenton and Intergrowth 21 charts

Variable

Unstandardized Beta

p-value

Unstandardized Beta

p-value

 Intubation

−196.278

.001

− 313.717

−78.839

− 145.980

.027

− 275.295

− 16.666

 Gender (females vs males*)

− 157.258

.004

−263.479

−51.038

− 140.141

.020

− 258.511

− 21.770

 In-vitro fertilization (yes vs no*)

− 398.452

< 0.001

− 521.357

− 275.548

− 437.977

< 0.001

− 573.322

−302.631

 Delivery method (C-section vs normal*)

− 19.570

.793

− 166.432

127.291

17.286

.836

− 147.337

181.910

 Any cause of prematurity (yes vs no*)

20.384

.378

−25.087

65.855

−8.373

.740

−58.030

41.283

 Consanguinity (yes vs no*)

37.530

.642

− 121.321

196.381

85.564

.337

−89.577

260.705

 Breastfeeding (yes vs no*)

33.230

.068

−2.498

68.958

42.203

.036

2.695

81.712

Variable

Unstandardized Beta

p-value

Unstandardized Beta

p-value

 Intubation (yes vs no*)

−1.053

.010

−1.855

−.251

−1.188

.006

−2.036

−.341

 Gender (females vs males*)

−.993

.008

−1.730

−.256

−.575

.147

−1.353

.203

 In-vitro fertilization (yes vs no*)

−1.604

< 0.001

−2.494

−.715

−1.573

.001

−2.506

−.641

 Delivery method (C-section vs normal*)

−.301

.551

−1.295

.694

−.388

.463

−1.431

.654

 Breastfeeding (yes vs no*)

.144

.249

−.101

.389

.143

.273

−.114

.401

 Any cause of prematurity (yes vs no*)

.080

.601

−.223

.383

.081

.616

−.238

.400

 Consanguinity (yes vs no*)

−.075

.895

−1.201

1.050

.332

.578

−.842

1.505

 Length percentile at birth

.065

< 0.001

.052

.078

.053

< 0.001

.040

.065

Variable

Unstandardized Beta

p-value

Unstandardized Beta

p-value

 Intubation (yes vs no*)

.391

.021

.060

.723

.194

.287

−.165

.554

 Gender (females vs males*)

−.237

.127

−.542

.068

.474

.010

.113

.836

 In-vitro fertilization (yes vs no*)

−.183

.311

−.537

.172

−.071

.720

−.461

.319

 Delivery method (C-section vs normal)

.012

.955

−.409

.433

.031

.896

−.428

.489

 Any cause of prematurity (yes vs no*)

.076

.247

−.053

.205

.032

.656

−.109

.172

 Consanguinity (yes vs no*)

−.008

.972

−.478

.462

.018

.943

−.493

.530

 Breastfeeding (yes vs no*)

.009

.865

−.094

.112

.069

.226

−.043

.180

 Head circumference at birth

.042

.000

.037

.047

.035

.000

.030

.040

Variable

Unstandardized Beta

p-value

Unstandardized Beta

p-value

 Intubation (yes vs no*)

− 164.040

.010

−287.562

−40.517

− 178.365

.003

−295.261

−61.469

 Gender (females vs males*)

− 111.614

.063

− 229.505

6.276

−35.214

.546

− 149.985

79.556

 In-vitro fertilization (yes vs no*)

−353.688

.000

− 487.945

− 219.430

− 363.595

.000

− 490.281

− 236.909

 Delivery method (C-section vs normal*)

−9.015

.917

− 179.313

161.283

9.309

.909

−151.824

170.442

 Any cause of prematurity (yes vs no*)

36.339

.171

−15.846

88.525

47.720

.059

−1.849

97.288

 Consanguinity (yes vs no*)

22.674

.801

− 154.905

200.254

44.992

.597

− 122.662

212.646

 Breastfeeding (yes vs no*)

−.757

.970

−40.738

39.223

−1.103

.954

−38.889

36.683

 Weight percentile at 2 weeks of age

11.378

.000

7.927

14.830

11.141

.000

8.496

13.785

Variable

Unstandardized Beta

p-value

Unstandardized Beta

p-value

 Intubation (yes vs no*)

.673

.230

−.448

1.794

.771

.128

−.235

1.777

 Gender (females vs males*)

−.579

.239

−1.562

.403

−.136

.769

−1.066

.795

 In-vitro fertilization (yes vs no*)

−1.872

.028

−3.528

−.217

−1.697

.029

−3.209

−.185

 Delivery method (C-section vs normal*)

−.984

.149

−2.339

.370

−.704

.261

−1.955

.547

 Any cause of prematurity (yes vs no*)

−.129

.570

−.588

.329

−.060

.770

−.474

.354

 Consanguinity (yes vs no*)

1.678

.059

−.070

3.426

1.177

.143

−.418

2.772

 Breastfeeding (yes vs no*)

−.161

.335

−.495

.173

−.149

.331

−.455

.158

 Length percentile at 2 weeks

.058

.000

.037

.079

.054

.000

.037

.070

Variable

Unstandardized Beta

p-value

Unstandardized Beta

p-value

 Intubation (yes vs no*)

− 349.864

.000

−511.389

−188.338

−287.552

.001

− 456.257

− 118.846

 Gender (females vs males*)

−214.487

.006

− 366.769

−62.205

− 104.602

.204

− 266.918

57.714

 In-vitro fertilization (yes vs no*)

−263.235

.003

−433.325

−93.146

− 316.056

.000

−490.141

−141.971

 Delivery method (C-section vs normal*)

−49.404

.659

− 270.890

172.083

−101.449

.380

−329.711

126.814

 Any cause of prematurity (yes vs no*)

60.329

.079

−7.030

127.689

96.435

.008

25.542

167.329

 Consanguinity (yes vs no*)

72.829

.508

−144.660

290.318

78.345

.491

−146.491

303.181

 Breastfeeding (yes vs no*)

−10.813

.692

−64.785

43.160

−13.781

.625

−69.600

42.038

 Weight percentile at 4 weeks

21.310

.000

17.484

25.136

18.974

.000

15.344

22.604

Variable

Unstandardized Beta

p-value

Unstandardized Beta

p-value

 Intubation (yes vs no*)

−1.278

.071

−2.668

.113

−.553

.465

−2.065

.959

 Gender (females vs males*)

−1.068

.055

−2.161

.024

−.559

.363

−1.784

.665

 In-vitro fertilization (yes vs no*)

−1.518

.016

−2.734

−.302

−1.096

.121

−2.493

.300

 Delivery method (C-section vs normal*)

−.298

.703

−1.859

1.264

−1.735

.053

−3.494

.025

 Any cause of prematurity (yes vs no*)

−.215

.364

−.689

.258

−.259

.325

−.783

.265

 Consanguinity (yes vs no*)

.317

.748

−1.660

2.294

1.860

.086

−.277

3.996

 Breastfeeding (yes vs no*)

−.127

.513

−.516

.262

−.149

.490

−.580

.282

 Length percentile at 4 weeks

.100

.000

.077

.124

.078

.000

.056

.100