For many parents, baby chairs, swings and other strap-in seats are undeniably convenient. But they could be costing our babies developmentally important "tummy time," according to the American Physical Therapy Association (APTA).

The APTA says that many babies are spending too much of their waking time on their backs and not enough time on their stomachs. And a lack of tummy time can delay infants' muscle development and mobility. The APTA cites a recent survey of 400 physical and occupational therapists in which two-thirds had seen an increase in early motor delays among infants over the past six years. An early motor delay happens when a child isn't able to meet important physical milestones in the first months and years of life. More than 80 percent of therapists listed a lack of tummy time as the No. 1 reason for this increase.

Read the rest of this blog about tummy time, as well as other children's health matters, in the Consumer Reports Health blog.