Table 2.

Mean Age (Months) for Milestone Acquisition

MilestoneProne SleepersMixed/Side SleepersSupine SleepersP Value* (Linear Regression)
Rolls prone to supine3.93  ± 1.24.48  ± 1.84.87  ± 1.33.002 (.02)
Rolls supine to prone4.9  ± 1.34.97  ± 1.95.0  ± 1.6.95
Sits supported4.7  ± 1.35.02  ± 1.45.13  ± 0.9.003 (.03)
Sits unsupported5.13  ± 1.15.17  ± 1.25.17  ± 1.0.80
Transfers object5.87  ± 1.25.99  ± 6.56.23  ± 1.1.11
Creeps6.07  ± 1.96.49  ± 1.97.23  ± 1.6.0002 (.001)
Crawls7.83  ± 2.08.47  ± 2.18.6  ± 1.7.003 (.05)
Pulls to stand8.1  ± 1.68.7  ± 1.58.77  ± 1.6.01 (.04)
Walks alone12.1  ± 2.012.2  ± 2.012.2  ± 1.7.4
  • * Represents P value for prone sleepers versus supine sleepers.

  • Multivariate regression analysis controlling for infant size, gender, ethnicity, presence of siblings, and maternal education.