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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