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Table 6 Parameter estimates modelling head circumference at birth (cm)

From: Optimal fetal growth for the Caucasian singleton and assessment of appropriateness of fetal growth: an analysis of a total population perinatal database

Independent Variable

Parameter Estimate

Standard Error

t value Pr >|t|

95% confidence limits

   Intercept

-88.31

1.92

-46.31 <.0001

-92.04

-84.57

   Scaled gestational age*

43.31

0.38

115.06 <.0001

42.57

44.05

   GA ln (GA) *

-287.6

5.1

-56.32 <.0001

-297.6

-277.6

   Male infant

0.6072

0.0109

55.89 <.0001

0.5860

0.6285

   Maternal height cm #

0.02745

0.000956

28.68 <.0001

0.0256

0.0293

   2nd birth

0.2352

0.0127

18.52 <.0001

0.210

0.260

   3rd birth

0.3151

0.0167

18.92 <.0001

0.282

0.348

   4th and subsequent birth

0.3394

0.0225

15.09 <.0001

0.295

0.384

   Maternal age #

0.01322

0.00110

12.01 <.0001

0.0111

0.0154

   GA# × Maternal height

0.00107

0.000498

2.14 0.0321

0.000091

0.00205

Adjusted R 2 for this model is 0.252

  1. * indicates non-centred but scaled GA, divided by 100
  2. # indicates a centred variable – GA centred around mean of 40 weeks, maternal height is centred around a mean of 162 cm, maternal age is centred around a mean of 25 years