Fetal movements are known to play a key role in prenatal skeletal development. We know this from a number of conditions in which reduced or restricted fetal movements are linked to abnormal  affecting newborn babies in which the bones or joints are not properly formed. The most common example is developmental dysplasia of the hip (DDH), where the hip joint is unstable or even dislocated. Another example is arthrogryposis, where multiple joints are abnormally shaped and oriented.

How does maternal exercise affect fetal skeletal development?

In exciting new work in collaboration with Dr Joel Boerckel & his team in University of Pennsylvania, we have found that when a pregnant mouse runs on a wheel, the mouse pups have significantly different bones and joints compared to litters in which there was no maternal exercise. In a collaborative team together with Prof Gareth Davison in Ulster University, we are currently working on figuring out how these effects on skeletal development are happening, such as the genes that are regulating the changes we see. We also want to find out how much exercise is needed to change the skeleton, and when is the most critical time. In the future we hope that an exercise therapy could be developed for women expecting a baby at increased risk of, or diagnosed with, conditions like hip dysplasia and arthrogryposis, so that their babies would have less severe skeletal effects after birth. The Dublin-based work is funded by Research Ireland’s US-Ireland R&D Partnership Programme. Watch this space for updates on what we discover!

Stresses and strains Induced by human fetal movements

In previous research, our team characterised- for the first time- the stresses and strains induced by fetal movements in the bones and joints, and how these stimuli are altered in conditions that predispose a baby to hip dysplasia. We created computer models of babies kicking in utero and calculated the stresses and strains induced in the bones and joints by these kicks. We found that the stresses in the fetal hip increase over pregnancy, even when the baby gets too big to make large movements at the hip. We also found that in situations which reduce the baby’s capacity to move (for example when they are in breech: head up rather than head down in the uterus), the mechanical stimulation at the hip joint is reduced, which could be what is leading to an increased risk of hip dysplasia.

Dr Stefaan Verbruggen was the postdoctoral researcher leading the research, and the project was funded by Arthritis Research UK (now Versus Arthritis). Fetal movements were automatically tracked from cine MRI scans (obtained from our collaborators at King’s College London) as shown below. Those movements were modelled using finite element and musculoskeletal models to calculate the force generated by the kick, and the muscle forces acting. Next, the muscle forces were applied to fetal skeletal geometries, obtained from collaborators in Great Ormond Street Hospital.