Table 3.

Age-adjusted and Fully Adjusted Effects (β) of Sleeping Position in SD Units on Development at 6 Months (With Significance Level of F Test for Improvement in Model Fit When Term Was Added)

Sleeping PositionnAge-adjusted β [95% CI]Fully Adjusteda β [95% CI]
Gross motor 
 Back1777 0.00 Ref 0.00 Ref
 Side6235−0.02 [−0.07, 0.02] 0.02 [−0.02, 0.07]
 Front 320 0.31 [0.20, 0.41] 0.38 [0.28, 0.49]
 Varies 774 0.13 [0.06, 0.21] 0.14 [0.06, 0.21]
 F test significance level 3-165,* 3-165,*
Fine motor
 Back1774 0.00 Ref 0.00 Ref
 Side6223−0.06 [−0.11, −0.01]−0.02 [−0.06, 0.03]
 Front 318−0.02 [−0.14, 0.09] 0.09 [−0.02, 0.20]
 Varies 771 0.05 [−0.03, 0.13] 0.07 [0.00, 0.15]
 F test significance level 3-165 **
Communication
 Back1772 0.00 Ref 0.00 Ref
 Side6222−0.04 [−0.09, 0.01]−0.04 [−0.09, 0.01]
 Front 318−0.07 [−0.18, 0.05]−0.08 [−0.20, 0.03]
 Varies 772 0.02 [−0.06, 0.10] 0.02 [−0.05, 0.10]
 F test significance levelNSNS
Social skills
 Back1773 0.00 Ref 0.00 Ref
 Side6220−0.02 [−0.07, 0.03] 0.02 [−0.03, 0.07]
 Front 318 0.07 [−0.05, 0.18] 0.11 [0.00, 0.23]
 Varies 771 0.01 [−0.07, 0.09] 0.02 [−0.06, 0.09]
 F test significance levelNSNS
Total score
 Back1772 0.00 Ref 0.00 Ref
 Side6218−0.05 [−0.09, 0.00] 0.00 [−0.05, 0.04]
 Front 318 0.11 [0.01, 0.22] 0.20 [0.10, 0.30]
 Varies 771 0.08 [0.00, 0.15] 0.09 [0.02, 0.16]
 F test significance level * *
  • a Adjusted for significant factors from the 27 described in “Methods.” NS indicates nonsignificant;

  • * P < .0001;

    P < .05.

  • F3-165 P < .01;

  • ** P < .001;