My 5 months old baby is still unable to raise his head during tummy time. Should i be concern?

Every baby is different, my baby is 7 months old, she can lift her head during tummy time or while laying flat on his back and looks like she's ready to sit on her own. But the thing is, she can't crawl unlike other 7-m.o babies. It's normal according to Pedia. So you don't have to be worried. Soon your baby will learn to lift his or her head just keep the tummy time routine for at least 15 minutes total every day.