Gynaecology & Obstetrics All are true regarding fetal skeletal mineralization except A Approximately 30g of calcium is needed especially during 3rd trimester. B Calcium required by fetus is only 10 % of maternal, skeletal calcium. C Amount of calcium absorbed increases to 400mg / day in the third trimester. D PTH plasma concentration is decreased in first trimester, but increases progressively later. 💡 Explanation All are true regarding fetal skeletal mineralization except ✓ Correct Answer: B. Calcium required by fetus is only 10 % of maternal, skeletal calcium.