My baby can’t lift his head and shoulder during tummy time

Ross

My baby is 16 weeks today. I noticed that the other September babies can now easily lift their head while on their tummy. When carried upright, my baby can support his head but we noticed that when on his tummy, he can’t lift it. We tried giving him tummy time but he cries as soon as we start.

Should I be concerned at this point or just need more tummy time?