Calcium supplements and bone resorption in pregnancy: a randomized crossover trial

Area of Science:

• Obstetrics and Gynecology
• Nutritional Science
• Bone Metabolism

Background:

• Pregnancy increases maternal calcium requirements.
• The impact of calcium supplementation on maternal bone resorption during pregnancy requires further investigation.
• This study examined calcium's role in maternal bone metabolism.

Purpose of the Study:

• To evaluate the effect of calcium supplementation on bone resorption in pregnant women.
• To assess changes in maternal bone turnover in response to calcium intake during the third trimester.

Main Methods:

• A randomized, crossover trial involving 31 pregnant women (25-35 weeks gestation).
• Participants received either 1200 mg of calcium or a multivitamin without calcium daily for 10 days each.
• Urinary levels of N-telopeptides of type I collagen (NTX), a bone resorption biomarker, were measured.

Main Results:

• 87.1% of participants showed reduced urinary NTX levels when taking calcium supplements.
• Mean urinary NTX levels were significantly lower (p<0.001) during calcium supplementation (83.2 nM BCE/mM creatinine) compared to multivitamin intake (96.8 nM BCE/mM creatinine).
• Neither maternal age nor dietary calcium intake predicted the treatment effect.

Conclusions:

• A 1200 mg bedtime calcium supplement effectively reduces maternal bone resorption by 14% in the third trimester.
• Calcium supplementation appears to decrease maternal skeletal-bone turnover during late pregnancy.
• These findings support the use of calcium supplements to manage bone metabolism in pregnant individuals.