By Ashley Reaver, MS, Registered Dietitian

Your bones are your body’s largest reservoir of calcium in the bone. While calcium is incredibly important for bone mineralization and strength, it plays critical roles in many functions in the body. Blood clotting, nerve impulse transmission, and contraction of the muscles are all critical processes that depend on calcium. The utilization of calcium in muscle contraction involves both voluntary muscle contraction, like our skeletal muscles, and involuntary muscle contraction, like our heart. Because of calcium’s key role in life-sustaining actions, the amount of calcium stored in the bone is readily utilized to maintain adequate levels of calcium in our blood for other activities. This is one reason why a blood calcium test is a poor measure for adequate calcium intake. 

Postpartum calcium needs

When you add on the requirements of growing another human’s bones and teeth, your body’s need for calcium becomes even greater. Interestingly, calcium needs don’t increase during pregnancy or breastfeeding, two times when your body’s usage of calcium is at an all time high. Instead, your body becomes better at absorbing calcium from your digestive tract with the help of vitamin D. Similar to the absorption of other minerals like iron, as your body’s needs increase, so does its ability to uptake what it needs. Typically, non-pregnant adults absorb only about 25% of the calcium we eat (which is factored into the overall recommended amount). While pregnant, however, this absorption rate doubles! 

Bone development starts around 8 weeks in babies. They continue to grow and deposit calcium until birth when they have 275 bones grown in part from the calcium you’ve contributed! They also have most of their first set of teeth (also made from calcium), although it will take a few months for them to pop through the gums. Research shows that towards the end of pregnancy, if maternal calcium levels are not sufficient, then calcium may be taken from the mother’s bones in order to provide adequate calcium for the fetus. Fortunately, pregnancy-related bone loss is typically restored and pregnancy is not related to an increased risk of osteoporosis or fracture later in life. 

Do calcium needs increase for breastfeeding?

During breastfeeding, the need for calcium is even more important. Unlike pregnancy, the digestive tract does not maintain its increased rate of absorption during breastfeeding. All calcium in the mother’s milk comes from the mother’s diet or from maternal bone stores if calcium intake from the diet is insufficient. Some mothers may experience bone loss, typically 3-7%, that can be restored within 6 months at the end of breastfeeding. 

Factors that influence bone mineral density

It is important to note that individual characteristics play a significant role in bone mineral density following pregnancy:

• Starting bone mineral density – those that have greater bone mineral density before pregnancy and lactation will likely have better bone mineral density following pregnancy and lactation
  • Bone mineral deposition peaks between ages 25-30 in women.
    • Ensuring adequate calcium and vitamin D intake during these years is crucial to meeting peak bone density.
    • Engaging in bone-stimulating activities like running, jumping, and strength training will also aid in the deposition of mineral in the bones.
• Maternal age during pregnancy and lactation may influence how and if all bone loss can be replaced since estrogen levels decrease with age and estrogen plays a critical role in deposition and maintenance of bone mineral density. As more women are having children later in life, we need more evidence to investigate this. 
• Racial differences, number of pregnancies, duration of time between pregnancies to regain bone loss, and length of breastfeeding are also important factors that will influence maternal bone health

Sources of Calcium

Calcium-rich foods include dairy products like milk and yogurt, as well as fortified non-dairy beverages. Vegetables like kale, broccoli, and Chinese cabbage also have high levels of calcium. Many breakfast cereals are fortified with calcium, too. Lastly canned sardines and salmon include the small, soft bones of the fish thereby contributing calcium, too. Calcium supplements should be discussed with your healthcare provider or registered dietitian during the postpartum period. 

Calcium is just one of the many nutrients to focus on during the postpartum period. Each playing a critical role in returning your body to its normal state following pregnancy and delivery. To learn more about all of the nutrients that impact your recovery and are essential for breastfeeding, explore our page, learn more about our course, or purchase or cookbook to easily achieve your nutrient needs while your focus is on your little one! 

References

Brown, LaVerne L et al. “Physiological Need for Calcium, Iron, and Folic Acid for Women of Various Subpopulations During Pregnancy and Beyond.” Journal of women’s health (2002) vol. 30,2 (2021): 207-211. doi:10.1089/jwh.2020.8873

Kalkwarf, H. J., & Specker, B. L. (2002). Bone mineral changes during pregnancy and lactation. Endocrine, 17(1), 49–53. https://doi.org/10.1385/ENDO:17:1:49

Salari, P., & Abdollahi, M. (2014). The influence of pregnancy and lactation on maternal bone health: a systematic review. Journal of family & reproductive health, 8(4), 135–148.

U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. 9th Edition