Babies spend approximately 8-9 months in their mother’s womb. When they are born, they go from crammed in a small space to having more freedom to move their arms and legs. However, because they are in a small space for so long, there are things to consider once a baby is born. In particular, the development of their hips is important.
Babies experience rapid hip development early in life1. It is important that as parents and caregivers, we promote good hip development and prevent potential complications. This article will describe what happens to a baby’s hips early in life, as well as how to promote good hip development. This article will also dip into baby carrying and the important role it has for a baby’s hip development.
When babies are born, it’s amazing how quickly they grow and develop. From the first smile, the first sound or babble to their first steps. Babies develop over months and years, and we seem to think this time passes by so quickly. Yet sometimes I don’t have the patience to wait 60 seconds for my leftover dinner to reheat in the microwave.
This rapid development also occurs in baby’s bones and joints, particularly the larger joints (hips, knees and ankles), haven’t quite formed yet. Think of a baby’s joints as an IKEA DIY: your baby has all the parts that make up their joints, now it’s down to your baby and you, their DIY buddy, to make it happen. Only this kind of DIY is significantly easier than putting together a bed frame or a chest of drawers.
Let’s purposely use the hip joint as an example. The hip is considered a ‘ball and socket’ joint. The ‘ball’ is the top of the thigh bone (the femur) and the ‘socket’, where the ball sits, is on the pelvis. However, in babies, the socket has not quite formed into a round shape. It is still relatively flat, making it difficult for the ball to fit in snug (see my lovely drawings). Therefore, the socket needs to form for the ball to fit in nicely.

A baby spends months and months in the womb with their hips bent. It is important to consider how a baby’s hips will adapt to their environment after birth and how parents and caregivers can promote good hip development.
How does the socket form? This is a somewhat lengthy explanation that I’ve tried to condense as much as possible, so here goes! The picture below shows a baby’s hip joints. The head of the thigh bone sits in water (AKA synovial fluid) to help create smooth leg movement. The pelvis, as you can see in figure 1, is still relatively flat and doesn’t look like a socket. Over time, the pelvis takes a curved-shape and the bone begins to thicken. The curving and thickening of the socket is caused by repeated movement of the thigh bone, or the ‘ball’ part of the joint. This compresses the fluid, causing an increase in pressure in the hip. This increased pressure helps to curve the socket and thicken the bone2. And voila! This is how your baby’s hips develop. But how do we create that pressure in the hip that helps the socket form? This will be explored later on. But for now, let’s go back to the baby in the womb.
When a mother is pregnant, her baby’s hips are bent right into their chest for months and months. Being in this position for so long causes your baby’s hip muscles to become very stiff3. After babies are born, they can move their hips more freely. However, stretching tight muscles too quickly can have negative effects on your baby. One example of stretching a baby’s hips is tight swaddling. Ensuring your baby’s swaddle is loose from the hips-down prevents over-stretching the hips and will allow your baby’s hip to develop appropriately.

Check out these lovely hand-drawn pics by yours truly. Number 1 is what a baby’s hips look like after birth. You have the pelvis, the thigh bones and some green stuff in between (fluid). Notice the pelvis is flat where the thigh bones meet it. This does not allow the ‘ball and socket’ to fit so easy. In number 2, the thigh bone fits more snug into the pelvis. This is how baby’s hip joints develop. This is also why I’m not an artist.
Another important consideration for your child’s hips is a baby carrier. When you look online, the choice of baby carriers is overwhelming. There are many considerations when choosing a baby carrier, which I will explore in a different blog. But the most important consideration is this: your child should be in a position that promotes good hip development. In figure 4, baby Evan is in his baby carrier with his mum Emily. Notice Evan’s hips are bent, with his knees up and his legs are spread apart. Looking from behind Evan, his legs have formed an M-shape. No matter how Evan moves his legs, the hips are in position to create that pressure in the hip required for some DIY joint creation. Evan is also prevented from over-stretching the hips when his legs are in the M-position4.

Evan is facing his mum Emily in his baby carrier. Notice how his hips are bent and legs spread apart, forming what’s known as the ‘M-Position’ (highlighted in red). The M-position allows promotion of good hip development.

Evan is facing outwards from his mum Emily in the baby carrier. Notice his hips are straighter than when he was facing his mum. This causes his hip muscles to stretch. This position is not dangerous for your baby but is less desirable for hip-development in the first 6 months5.

I hope you found this article/blog useful and had a giggle over my awful drawings. There was a lot to unpack (excuse the IKEA pun) and discuss. The 2 key takeaways I hope you get from this are as follows:
- Baby’s hip joints develop at a rapid rate, especially in the first 6 months after birth.
- There are ways we can promote good hip development early in life, such as how we swaddle our babies and choosing the right baby carrier for them.
There are many baby carriers out there to choose from. I will discuss baby carriers and dig further into considerations in a separate blog. In the meantime, you can browse products that promote your baby’s hip development below. These have been approved by the International Hip Dysplasia Institute (IHDI). The IHDI spend more time on the research of hip development than I do trying to pick a Netflix show to binge on.
Hip-Healthy Products
References:
- Cho, S., & Kim, C. (2019). Ergonomic Differences between Baby Carriers by Certain Wearing Positions. Journal of International Academy of Physical Therapy Research, 10(2), 1774-1778.
- Frost, H. M. (2004). A 2003 update of bone physiology and Wolff’s Law for clinicians. The Angle Orthodontist, 74(1), 3-15.
- Clarke, N. M. P. (2014). Swaddling and hip dysplasia: an orthopaedic perspective. Archives of disease in childhood, 99(1), 5-6.
- Price, C. T (2008). Infant Carrier Design Considerations Criteria for “Hip-Healthy” Designation. International Hip Dysplasia Institute.
- Fettweis, E. (2010). Carrying babies or toddlers in baby carriers or shawls. Orthopädische Praxis, 46(2), 93-98.