Doctor Nguyen Van Cong, a specialist in Obstetrics and Gynecology at Tam Anh General Hospital in Hanoi, states that osteoporosis is common in postmenopausal women. This condition occurs when bone mineral density falls below a safe threshold, making bones brittle and prone to fractures. In breastfeeding women, bone density can decrease by 3-7% during the initial six months postpartum, with several contributing factors.

Increased calcium demand for milk production

On average, a mother produces about 700-800 ml of milk daily, which equates to a loss of approximately 200-300 mg of calcium. This calcium is preferentially channeled into breast milk to ensure the baby's skeletal development.

If the diet does not provide enough calcium, around 1,000-1,300 mg daily, the body must mobilize calcium from the bones to maintain milk quality. This natural physiological mechanism protects the infant but can lead to a significant decline in the mother's bone density if prolonged.

Postpartum hormonal changes

Estrogen, a hormone that inhibits bone resorption and retains calcium in the bone structure, decreases sharply after childbirth. Concurrently, prolactin levels rise to stimulate milk production. This hormonal shift increases the activity of bone-resorbing cells and reduces new bone formation, accelerating bone loss.

Vitamin D deficiency

Vitamin D enhances calcium absorption in the intestines and regulates bone metabolism. However, many postpartum women tend to avoid going outside and limit sun exposure, leading to vitamin D deficiency which hinders this process.

Lack of physical activity

Prolonged bed rest and minimal physical activity also impair bone formation. Bone is living tissue that requires stimulation from weight-bearing activities, such as walking or light exercise, to maintain its density. When the body is inactive, bone remodeling slows down.

Consecutive pregnancies and births

During pregnancy, the mother's body must supply a large amount of calcium to the fetus. The body employs regulatory mechanisms to protect the skeletal system, such as increased calcium absorption from food and supplements, which is more efficient than in non-pregnant states. Additionally, the body produces more estrogen, which protects bones, enhances calcium binding to the skeleton, and limits bone loss.

After childbirth, these protective mechanisms decline, especially the decrease in estrogen levels due to temporary ovarian inactivity. If the interval between births is too short, the skeletal system may not fully recover before entering a new cycle of calcium loss. Cumulative bone loss over multiple pregnancies and breastfeeding periods can elevate the risk of osteoporosis.

A doctor at the Obstetrics and Gynecology Center is consulting a woman. Photo: Tam Anh General Hospital

According to doctor Cong, reduced bone density often progresses silently and is difficult to detect in its early stages. Many women only discover it incidentally during health check-ups or when complications arise. Some might experience persistent back pain, especially in the lumbar spine, bone fatigue, muscle weakness, cramps or numbness in the limbs, slight height reduction, or fractures after minor impacts. In rare cases, new mothers may experience vertebral compression fractures within months of giving birth.

Bone loss during breastfeeding is largely physiological and often reversible. Once the child is weaned, estrogen levels gradually return to normal, ovarian function recovers, and the menstrual cycle resumes, activating bone formation to replenish the bone lost during the breastfeeding period.

However, this recovery depends on an individual's nutritional foundation, lifestyle, and number of pregnancies. If calcium and vitamin D deficiencies persist, physical activity is low, or births occur in quick succession, bone density may not fully recover.

For mild bone density reduction, doctors typically prioritize conservative measures. Mothers are advised to adequately supplement calcium and vitamin D as needed, adjust their diet to be rich in nutrients, increase intake of natural calcium-rich foods, and maintain light weight-bearing exercises suitable for their physical condition.

In cases of severe osteoporosis or fractures, treatment requires careful consideration. Many osteoporosis medications are not recommended for use during breastfeeding due to potential risks to the infant. If necessary, doctors may consider temporarily suspending breastfeeding to use specific medications, while closely monitoring bone status and motor function.

To protect the skeletal system during breastfeeding, the diet should ensure sufficient calcium from milk and dairy products, small fish eaten with bones, shrimp, crab, tofu, and dark green vegetables. Appropriate vitamin D supplementation through morning sun exposure or medical advice is also essential.

Early and suitable physical activity, such as walking or postnatal yoga, helps stimulate bone formation and increase muscle strength. Avoid extreme dietary restrictions and maintain a diverse diet with adequate protein and micronutrients. Spacing births appropriately, around two to three years between pregnancies, allows the body sufficient time to regenerate bone density.

If experiencing severe back pain, pain that increases with movement, or fractures from minor trauma, women should seek medical attention promptly for a bone density scan.

Trinh Mai