Bone health in premature babies

What is metabolic bone disease of prematurity?

Very premature babies are at risk for metabolic bone disease, a condition that affects their bone health and increases the risk of fractures. It is usually diagnosed using screening tests before a baby develops symptoms. If untreated, babies can develop osteopenia (a decrease in bone density or strength) or rickets (softening or weakening of the bones).

Signs and symptoms of metabolic bone disease of prematurity

Metabolic bone disease of prematurity often has no symptoms.

• Early stages of metabolic bone disease of prematurity do not affect the way a baby’s bones look on X-ray.
• When the disease is more severe, bones are weak and brittle, and fractures may occur spontaneously and have no symptoms or be accompanied by swelling or decreased movement.

What causes metabolic bone disease?

The third trimester is an important stage in the development of a fetus’ bones. Very premature babies are born before several important events occur:

• Calcium and phosphorus, which are both needed to strengthen bones, are transferred rapidly to the fetus through the placenta during the last trimester of pregnancy.
• Fetal activity, such as moving and kicking during the third trimester, also helps strengthen bones.

After birth, very premature babies face other obstacles to protecting their bone health:

• They lose more phosphorus through their urine.
• Depending on their medical condition, they may require medications that affect calcium levels in their blood.
• Babies on total parenteral nutrition (TPN; nutrition via IV) may not receive enough calcium and phosphorus.
• Some medical conditions may affect a baby’s ability to absorb enough vitamins and minerals in the digestive system.
• The availability of calcium and phosphorus will affect the mineralization of a baby’s bones.

Very premature babies or babies with a birth weight of <1500 g are most at risk for metabolic bone disease of prematurity.

How is metabolic bone disease of prematurity diagnosed?

Early metabolic bone disease of prematurity is diagnosed based on screening blood tests that assess bone health, as well as X-rays and clinical exams.

How can bone health be optimized in premature babies?

Ways to prevent metabolic bone disease include:

• early screening of bone health
• fortification of feeds to provide higher levels of calcium and phosphorus
• early supplementation of vitamins and minerals to promote bone mineralization
• parents holding and handling their baby

As babies grow and near discharge, their nutritional needs for bone health may improve, and supplements and feeds may be modified.

Complications and long-term outcomes

Some babies in the NICU will develop fractures as a result of their bone disease. This will be recognized and treated by the health-care team who will discuss details with you around treatment and follow up.

An increased risk for fracture can persist through the first year of life for very premature infants. This risk does not persist later in childhood in premature babies who receive adequate vitamin and mineral supplementation.

References

American Academy of Pediatrics. (2022). Osteopenia in newborns and infants. Retrieved from https://www.aap.org/en/patient-care/newborn-and-infant-nutrition/osteopenia-in-newborns-and-infants/

Faienza, M. F., D'Amato, E., Natale, M. P., Grano, M., Chiarito, M., Brunetti, G., & D'Amato, G. (2019). Metabolic Bone Disease of Prematurity: Diagnosis and Management. Frontiers in pediatrics, 7, 143. https://doi.org/10.3389/fped.2019.00143

Kuitunen, I., Sund, R. & Sankilampi, U. (2023). Association of Preterm Birth and Low Birthweight with Bone Fractures during Childhood. Journal of Bone Mineral Research, 38:8, 1116-1124. https://doi.org/10.1002/jbmr.4833