Deformational Plagiocephaly is most commonly caused by keeping an infant's head in one position for long periods of time. This causes a flat spot in the skull to form. Sometimes, a baby is born with a flat spot because of a tight intrauterine environment (multiple births, small maternal pelvis or with a breech position).
Other factors which may increase the risk of deformational plagiocephaly include:
Muscular Torticollis: Muscular torticollis is when a baby is born with very tight neck muscles. This causes the head to tilt or turn in the same direction. Since the infant holds their head against the mattress in the same position repeatedly, a flat spot can form.
Prematurity: Premature infants are at a higher risk for plagiocephaly. This is because the cranial bones become stronger and harder in the last 10 weeks of pregnancy. Also, since many premature infants spend a long time in the Neonatal Intensive Care Unit (NICU) on a respirator, their heads are maintained in a fixed position, increasing the risk.
Back Sleeping: Infants who sleep on their backs or in car seats without switching positions for a long time are also at a higher risk for deformational plagiocephaly.