Developmental dysplasia of the hip is a condition where the hip joint does not form properly in babies and young children, causing the ball at the top of the thighbone to fit loosely or slip out of its socket. This common condition affects approximately 1 to 2 babies per 1,000 births, and with early detection and treatment, most children grow up to lead active, healthy lives without long-term hip problems.

Understanding How Common This Condition Is

Developmental dysplasia of the hip, often shortened to DDH, occurs in about 1 in every 1,000 babies born in the United States each year. The condition is significantly more common in certain groups of babies than others. Girls are affected two to four times more often than boys, making gender one of the most important factors in who develops this condition.^[1][2]

First-born children face a higher risk of DDH compared to babies born later in the family. The left hip is affected more frequently than the right hip in about 80% of cases, though some babies may have the condition in both hips. Babies born in certain positions, particularly those who were in a breech position during the third trimester of pregnancy, show notably higher rates of hip dysplasia.^[1][7]

Across different populations, the incidence can vary. Some cultures that traditionally hold infants with their hips spread apart have lower rates of DDH, while cultures that swaddle babies tightly with legs extended show higher rates. This suggests that how babies are positioned in early life may influence whether the condition develops or worsens.^[8]

What Causes the Hip Joint to Develop Abnormally

The exact cause of developmental dysplasia of the hip remains somewhat unclear, but researchers believe multiple factors work together to create the problem. The condition is not typically caused by one single issue, but rather a combination of genetic, environmental, and mechanical influences that affect how the hip joint forms.^[4]

Genetics plays an important role in many cases. DDH tends to run in families, meaning if a parent had hip problems as a child, their baby faces a 12% higher risk of developing the condition. When a sibling has had DDH, other children in the family have about a 6% increased risk. If both a parent and a sibling were affected, the risk jumps to 36%, or roughly one in three.^[7][12]

The baby’s position during pregnancy matters significantly. When a baby is in a breech position, especially with feet up by the shoulders during the third trimester, the risk of DDH increases dramatically. These babies are ten times more likely to develop hip dysplasia than babies born head-first. A tight uterus that limits how much the baby can move, which often happens with first pregnancies, can also contribute to abnormal hip development.^[1][2]

Low levels of amniotic fluid during pregnancy, a condition called oligohydramnios (meaning reduced fluid in the womb), may restrict fetal movement and increase pressure on developing joints. The mother’s hormones during pregnancy can also affect the baby, causing ligaments to become extra stretchy and loose, which may lead to hip instability.^[8][19]

Who Faces Higher Risk

Several groups of babies are at notably higher risk for developmental dysplasia of the hip. Understanding these risk factors helps healthcare providers know which babies need extra monitoring and early screening.

Female babies represent the largest at-risk group. The reason girls are more susceptible is not completely understood, but it may relate to how they respond to maternal hormones during pregnancy. First-born babies also face elevated risk, likely because the uterus is tighter during a first pregnancy, limiting space for the baby to move and potentially affecting hip development.^[1][2]

Babies who spent time in a breech position, particularly during the final months before birth, constitute another high-risk group. The American Academy of Pediatrics now recommends ultrasound screening for all female babies who were breech. Family history matters too—babies whose parents or siblings had childhood hip problems should be watched more closely.^[2][3]

Some babies are born with other conditions that may occur alongside hip dysplasia, such as clubfoot or torticollis (head tilt). These conditions can signal that the baby faced constraints in the womb, alerting doctors to check the hips carefully. Recent research has also shown that babies whose legs are swaddled tightly with hips and knees held straight face notably higher risk for developing DDH after birth, even if they were not born with it.^[2][12]

Recognizing the Signs and Symptoms

One of the challenges with developmental dysplasia of the hip is that it rarely causes pain in babies and young children, making it easy to miss. Many babies with DDH show no obvious symptoms that parents can notice at home. This is why healthcare providers check every baby’s hips during routine examinations.^[1][3]

When symptoms do appear, they often involve differences between the two legs or hips. Parents might notice that their baby’s hips make a popping or clicking sound that can be heard or felt when the legs are moved. One leg may appear shorter than the other, though the bones are usually the same length—the difference comes from the position of the bones in the joint.^[1][7]

The range of motion may differ between the two hips. During diaper changes, one leg might not spread apart as easily as the other. One hip or leg may not move the same way as the other side, or one leg may turn outward more than its partner. Parents might observe that the skin folds under the buttocks or on the thighs don’t line up evenly, appearing uneven or wrinkled on one side.^[1][7]

In toddlers who have begun walking, the symptoms may become more noticeable. A child with DDH might develop a limp, or they may waddle when they walk if both hips are affected. Even though these symptoms are present, young children with hip dysplasia typically do not complain of pain. Pain usually only develops later in life if the condition goes untreated.^[1][9]

Steps to Prevent Hip Problems

While developmental dysplasia of the hip often cannot be completely prevented due to genetic and prenatal factors, parents can take steps to reduce the risk of making the condition worse or causing it to develop after birth.

Safe swaddling practices are crucial during the first months of life. When swaddling a baby, parents should ensure the baby’s legs can bend up and out at the hips, rather than being held straight and pressed together. The lower body should have room to move, even when the upper body is wrapped snugly. Tight swaddling with legs extended has been linked to higher rates of hip dysplasia, particularly in cultures where this practice is common.^[2][8]

Choosing appropriate baby carriers matters too. Using carriers that support the baby in a position with legs spread apart and thighs supported—sometimes called the “frog” or “M” position—helps maintain healthy hip development. Narrow carriers that force the baby’s legs straight down and together should be avoided.^[8]

Regular well-child visits provide opportunities for healthcare providers to examine the hips and catch any problems early. Babies at higher risk due to family history, breech position, or being female and first-born should receive careful monitoring. Some may need ultrasound screening between 4 and 6 weeks of age to check hip development, even if no obvious symptoms are present.^[3][18]

How the Hip Changes in DDH

To understand developmental dysplasia of the hip, it helps to know how a normal hip joint works. The hip is a ball and socket joint (meaning one bone ends in a round ball that fits into a cup-shaped hollow in another bone). The top of the thighbone (called the femur) ends in a rounded ball called the femoral head. This ball fits into a socket in the pelvic bone called the acetabulum. The ball moves around in different directions but normally stays firmly inside the socket, allowing us to move our hips and supporting our body weight.^[1][2]

In DDH, several problems can occur with this joint. The socket may be too shallow to hold the ball properly, meaning the femoral head is not held tightly in place. Ligaments (the bands of tissue that connect bones to each other) may be stretched or extra loose, failing to keep the joint stable. The cartilage (smooth protective tissue that lines the bones and reduces friction) may not develop properly.^[2][3]

The severity of hip instability varies considerably among children with DDH. In the mildest cases, called subluxatable hips, the femoral head is loose in the socket and can be moved around within it during examination, but it doesn’t actually come out. In dislocatable cases, the femoral head lies within the socket but can be easily pushed out during a physical exam. In the most severe cases, called dislocated hips, the head of the femur is completely out of the socket and stays that way.^[2][12]

When the hip joint does not form properly and remains misaligned, it affects how the bones grow and develop. The socket may become increasingly shallow over time, and the femoral head may change shape rather than remaining round. If left untreated, this abnormal development leads to poor fit between the bones, causing the joint to wear out much faster than normal. This early wear can result in painful arthritis (inflammation and wearing down of the joint) before a person reaches age 60, and it may cause difficulty walking and hip pain at a young age.^[1][9]

Many babies are born with hips that feel loose when moved around, a condition called neonatal hip laxity. This happens because the ligaments are extra stretchy, often due to the mother’s hormones still affecting the baby’s body. Neonatal hip laxity is different from true developmental dysplasia of the hip. It usually resolves on its own by 4 to 6 weeks of age without treatment. However, if the hip ligaments remain loose after 6 weeks, the baby might need treatment, making follow-up visits important for babies born with loose hips.^[1][24]