Causes of Developmental Dysplasia of the Hip
The causes of DDH aren't completely understood, but experts think that many things are involved. A baby can be at risk for DDH due to:

Bring cramped in the uterus. A fetus can develop DDH when there is less space to move inside the womb. This is more likely to happen in first pregnancies when the uterus is tight, or in pregnancies where there is less amniotic fluid in the womb.

Breech position. Being in the breech position (buttocks facing the birth canal) can limit movement in the womb, especially when the baby's knees extend out with the feet near the head (called "frank breech").

Other conditions. Babies born with conditions that are caused by their position in the womb, like metatarsus adductus (an inward curving of the foot), torticollis (stiff neck), and flat head syndrome (positional plagiocephaly), are more likely to develop DDH.

Birth hormones. DDH also may be caused by an infant's response to the mother's hormones that relax the ligaments for labor and delivery, causing the baby's hip to soften and stretch during labor.

Tight swaddling. After birth, swaddling a newborn too tightly around the hips can sometimes cause DDH. (When swaddled, a baby should still have some wiggle room for the legs, with hips and knees bent slightly and turned out.)