My seven-month-old can sit, crawl, is able to stand, and can cruise (walk while holding onto furniture and people). He has been going to daycare for two weeks. Daycare constantly sends pictures to show his progress. But ever since the start of this week, daycare puts him into the high chair for him to sit, and only takes him off when he wants to sleep. Will this harm my child's spin and body? I heard that sitting for a long period will harm a child. I also worry because he doesn't get a chance to crawl, and crawling is is good for a child at his age. Isn't the daycare doing more harm than good at this point? Should I be worried?
You are correct - it is detrimental to their growth.
A child should not sit in a high chair or other equipment that constrains his/her movement (1,2) indoors or outdoors for longer than fifteen minutes, other than at meals or snack time. Children should never be left out of the view and attention of adult caregivers/teachers while in these types of equipment/furniture. A least restrictive environment should be encouraged at all times. Children should not be left to sleep in equipment, such as car seats, swings, or infant seats that does not meet ASTM International (ASTM) product safety standards for sleep equipment.
While they are at least removing your child from the high chair for naps, if they are indeed keeping your child in a highchair for extended periods of time then that could be detrimental to their growth.