How do pregnancy and breastfeeding affect a woman’s bones?

Calcium is in high demand during both pregnancy and breastfeeding – since it is needed to support the baby’s growth and development in the mother’s womb and after birth.

Some of these calcium needs are met by the movement of calcium out of the mother’s bones, through a process called remodeling (See What Is Bone?), especially during the third trimester and during breastfeeding.

How much calcium do pregnant and breastfeeding women need to keep their bones healthy?

The amounts of calcium that women need do not change when they are pregnant or nursing. The recommended amount for teen girls age 14 to 18 is 1,300 mg a day. Women who are older than age 18 should get 1,000 mg of calcium a day.

Getting more than the recommended amount of calcium from food or supplements does not prevent the loss of calcium from bones during pregnancy or nursing. So, extra calcium does not have much effect on how much bone mass a woman loses at this time of life.

Pregnant and nursing women who are thinking about taking a calcium supplement should talk to their health care provider.

Although decreases in bone density are a normal part of pregnancy and lactation, in very rare cases, pregnant and nursing women can develop osteoporosis. Osteoporosis causes bones to become weak and brittle, which increases the risk of fractures (broken bones).

Fractures in these women may occur spontaneously or as the result of normal activities, with minimal trauma or stress. Spine fractures are the most common in pregnant or nursing women with osteoporosis, but other types of fractures may happen. In some cases, the mother has a known medical condition or is taking a medication that increases her risk of osteoporosis and fracture.

What are the long-term effects of pregnancy and breastfeeding on bones?

Temporary decreases in bone density are a normal part of pregnancy and breastfeeding. However, bone density is typically restored after pregnancy and during/after weaning.

Recent large studies show that pregnancy and breastfeeding are not associated with increased risk of osteoporosis or fractures later in life.