Table 2 Comparison between normal and developmental delayed children with respect to perinatal and physical examination variables

Variables in terms of children

 Child—Sex

  Female

78,652(95.8)

3443(4.20)

77,976(95.0)

4119(5.0)

78,349(95.4)

3746(4.6)

77,773(94.7)

4322(5.3)

  Male

91,515(95.20)

4625(4.80)

< 0.001*

91,245(94.9)

4895(5.1)

0.476

91,100(94.8)

5040(5.2)

< 0.001*

89,693(93.3)

6447(6.7)

< 0.001*

 Parity of more than three children

  No

169,686(95.5)

8029(4.5)

168,741(95.0)

8974(5.0)

168,971(95.1)

8744(4.9)

166,982(94.0)

10,733(6.0)

  Yes

481(92.5)

39(7.5)

0.001*

480(92.3)

40(7.7)

0.006*

478(91.9)

42(8.1)

0.001*

484(93.1)

36(6.9)

0.398

 Multiple birth

  Singleton

168,824(95.5)

7978(4.5)

167,894(95.0)

8908(5.0)

168,107(95.1)

8695(4.9)

166,143(94.0)

10,659(6.0)

  Twins/multiple birth

1343(93.7)

90(6.3)

0.001*

1327(92.6)

106(7.4)

< 0.001*

1342(93.6)

91(6.4)

0.013*

1323(92.3)

110(7.7)

0.009*

 Gestational weeks

  37–42 weeks

168,663(95.5)

7998(4.5)

167,719(94.9)

8942(5.1)

167,955(95.1)

8706(4.9)

166,002(94)

10,659(6)

  < 37 weeks

795(95.2)

40(4.8)

0.715

795(95.2)

40(4.8)

0.721

790(94.6)

45(5.4)

0.539

767(91.9)

68(8.1)

0.011*

  ≥ 42 weeks

709(95.9)

30(4.1)

0.542

707(95.7)

32(4.3)

0.366

704(95.3)

35(4.7)

0.810

697(94.3)

42(5.7)

0.690

 Neonatal injury

  No

169,718(95.5)

8028(4.5)

168,778(95.0)

8968(5.0)

169,000(95.1)

8746(4.9)

167,008(94)

10,738(6)

  Yes

449(91.8)

40(8.2)

< 0.001*

443(90.6)

46(9.4)

< 0.001*

449(91.8)

40(8.2)

0.001*

458(93.7)

31(6.3)

0.782

 Head circumference at physical examination

  Normal

160,926(95.5)

7618(4.5)

160,051(95)

8493(5)

160,277(95.1)

8267(4.9)

158,364(94.0)

10,180(6.0)

  Macrocephaly

6782(95.7)

302(4.3)

0.308

6723(94.9)

361(5.1)

0.83

6715(94.8)

369(5.2)

0.247

6674(94.2)

410(5.8)

0.382

  Microcephaly

2459(94.3)

148(5.7)

0.005*

2447(93.9)

160(6.1)

0.011*

2457(94.2)

150(5.8)

0.047*

2428(93.1)

179(6.9)

0.079

 BMI at birth

Normal

158,521(95.6)

7312(4.4)

157,593(95)

8240(5)

157,845(95.2)

7988(4.8)

155,964(94.0)

9869(6.0)

  Malnutrition

7177(93.2)

523(6.8)

< 0.001*

7162(93)

538(7)

< 0.001*

7154(92.9)

546(7.1)

< 0.001*

7106(92.3)

594(7.7)

< 0.001*

  Obesity

4469(95)

233(5)

0.073

4466(95)

236(5)

0.876

4450(94.6)

252(5.4)

0.087

4396(93.5)

306(6.5)

0.112

 BMI at physical examination

  Normal

157,423(95.5)

7356(4.5)

156,565(95.0)

8214(5.0)

156,811(95.2)

7968(4.8)

154,885(94.0)

9894(6.0)

  Malnutrition

1697(93.1)

126(6.9)

< 0.001*

1649(90.5)

174(9.5)

< 0.001*

1696(93)

127(7)

< 0.001*

1701(93.3)

122(6.7)

0.219

  Obesity

11,047(95.0)

586(5.0)

0.004*

11,007(94.6)

626(5.4)

0.058

10,942(94.1)

691(5.9)

< 0.001*

10,880(93.5)

753(6.5)

0.040*

Variables in terms of parents

 Advanced maternal age

  No

165,341(95.5)

7765(4.5)

164,375(95.0)

8731(5.0)

164,610(95.1)

8496(4.9)

162,683(94.0)

10,423(6.0)

  Yes

4826(94.1)

303(5.9)

< 0.001*

4846(94.5)

283(5.5)

0.127

4839(94.3)

290(5.7)

0.015*

4783(93.3)

346(6.7)

0.032*

 Cesarean section

  No

98,392(95.6)

4578(4.4)

97,895(95.1)

5075(4.9)

97,959(95.1)

5011(4.9)

96,842(94.0)

6128(6.0)

  Yes

71,775(95.4)

3490(4.6)

0.055

71,326(94.8)

3939(5.2)

0.004*

71,490(95)

3775(5)

0.151

70,624(93.8)

4641(6.2)

0.060

 Variables in terms of the environment and inheritance

  Per capita GDP

3.62 ± 0.96a

3.40 ± 0.82 a

< 0.001*

3.62 ± 0.96 a

3.51 ± 0.86 a

< 0.001*

3.63 ± 0.96 a

3.30 ± 0.81 a

< 0.001*

3.62 ± 0.96 a

3.39 ± 0.83 a

< 0.001*

 Family heredity history

  No

169,631(95.5)

8032(4.5)

168,693(95.0)

8970(5.0)

168,928(95.1)

8735(4.9)

166,940(94.0)

10,723(6.0)

  Yes

536(93.7)

36(6.3)

0.042*

528(92.3)

44(7.7)

0.004*

521(91.1)

51(8.9)

< 0.001*

526(92)

46(8)

0.044*