Plagiocephaly is a fancy word for mis-shapen head. It can happen for many different reasons in a small infant, especially since their heads are malleable and change shape easily.
My now 20 month old son had a slighly flat spot on the back of his head because he was positioned upright and reclined which put pressure on his head. We had to position him like that due to his severe reflux. I think the flat spot would have been worse had I not put him in "tummy time" so much of his waking hours. Of course, I couldn't lay him in this position until at least 45-60 minutes after a feeding or he would vomit. Once he got around 5-6 months of age, he would roll over and sleep on his tummy. By 7 months he was crawling. These things in addition to all of the reflux medications he was on contributed to a better head shape by 8-9 months of age. His head shape was never severe enough for a helmet. But I explained his situation to indicate how easy it is for a child's head to get mis-shapen and back to being okay.
Often, a baby with torticollis or neurological damage is prone to plagiocephaly. Also, babies with medical problems who aren't able to move age-appropriately, such as preemies, those with heart defects, and babies who have had multiple surgeries. Another reason can be being a multiple (twins, triplets, or more) or a large baby born to a petite mom; this is because there isn't as much wiggle room and they may get stuck with the neck and head in an awkward position.
If your child has been diagnosed with plagiocephaly then hopefully he/she is getting occupational and/or physical therapy services. Therapy can help with neck/trunk strength, stretches, and massage as well as helping with any necessary adaptive equipment to help reposition the baby.
Some simple strategies to help when the head is mis-shapen on the left or right side:
-switch the way the baby is carried, sometimes over the left shoulder and sometimes over the right
-switch the way the baby is held when being fed, sometimes on your right side, other times to your left side
-when using a changing table for diapering, alternate which end the baby's head is at, this helps the baby to look in different directions
-move positioning equipment within the room: bouncy seat, bouncers, swings, etc. so that the view is not always the same for the baby
-when approaching the baby as he/she is in a device or on the floor on a blanket, come from different directions to help the baby look to each side as well as overhead and to the front
-don't sit the child in a Bumbo (R) seat or standing bouncer before he/she has the trunk control to be in it. This is also the case with Jumparoos (R) and Johnny Jump Ups (R). If the baby doesn't have enough trunk or head control, then he will lean to the side which only perpetuates the asymmetry of the head
-offer the baby toys to each side of him wherever he is: swing, floor overhead gym, carseat, on tummy on blanket on floor, etc.
-get down on the floor and play with the baby, sometimes be on his right side, other times on the left or to the front
-infant massage indirectly initially such as to the belly or legs, and then if tolerated to the chest, neck, and arms
-follow through with all exercises/stretches given by the PT and/or OT. Be careful about getting aggressive stretches off of the internet, because depending upon the etiology of the plagiocephaly these stretches could be hurting the baby
Final thought: if your child's doctor prescribes a helmet to help with head shape, then by all means get a helmet and use it the suggested wearing schedule (usually 23 hrs a day). I have seen some amazing changes in head shapes of babies with helmets.
To see pictures of plagiocephaly and helmets, visit www.cranialtech.com