Why won't my baby lift his head?

Q: Why does my 4 month old hold his head down when I carry him, even though he can lift his head?

A: Perhaps your infant carrier or sling does not allow him to turn or lift his head upwards, but a 4-month-old baby who was born on time (not prematurely) should be able to lift his head up when lying on his belly.  He should also be able to hold his head up and look around when being carried in an upright position (unless there is something interesting to look at on the floor!). If he is capable of these milestones, then he has appropriate muscle strength. Otherwise, consult your baby's pediatrician for a closer examination.