Since calcium functions as an essential part for bone and tooth structure, your need for this mineral is obviously great. Your body compensates for this additional need by increased absorption and retention of calcium long before your fetal skeletal mineralization begins. Approximately 30 gm of calcium are accumulated during pregnancy, almost all of it by the fetal skeleton. About 300 mg of calcium per day is deposited during the last three months of pregnancy. Observations have led researchers to suspect that maternal tissues retain calcium as well, possibly in preparation for meeting the extensive calcium requirements of breastfeeding.

The current RI for calcium is approximately 1000-1300 mg per day. Some scientists feel that this recommendation is too high since successful pregnancies are sustained on much lower calcium intake by many cultures. But it is likely that the difference between intake and requirement would be met by the body removing calcium from maternal stores such as bones and teeth. After several pregnancies, the harmful effects of this practice may show up in your body as decreased amounts of calcium in your bones. Babies born to women under these conditions show poor bone formation as well. Also, it is known that the calcium requirement is linked to protein and phosphorus intake and that diets high in one or both of these nutrients cause higher calcium losses in the urine; this presumably increases the dietary requirement for calcium.

While calcium is found in a number of foods, it is present in highest quantities in milk and other dairy products. If you are intolerant to milk, you will need to find an alternative calcium source. Soybean products and leafy green vegetables are among the better nondairy sources.

Calcium-phosphorus balance is frequently discussed in relation to nerve and muscle function. Some pregnant women seem to be particularly prone to cramping of the muscles of the lower leg, especially at night. Twenty years ago, several doctors suggested that this condition might be caused by the presence in the blood of too little calcium for the amount of phosphate) present. In order to treat this problem, they prescribed reduction in milk intake (a food high in phosphorus and calcium), supplementations of the diet with non-phosphate calcium salts, and aluminum hydroxide (to reduce absorption of phosphorus from the intestine). These measures were shown to increase the blood levels of calcium in these women. However, not all of the studies demonstrated a beneficial effect on leg cramps. Thus, there is still controversy regarding the cause of leg cramps. Improvements of calcium-phosphorus balance by the use of calcium gluconate and aluminum hydroxide may be helpful if you are severely affected by leg cramps.

But, as with all other diet supplements, consult your clinician before beginning treatment. Avoiding milk products as a portion of the treatment seems inappropriate only if all other measures have failed. The high nutritional value of milk products, particularly in pregnancy, certainly justifies its presence in the diet if at all possible. Reduction of low-calcium high-phosphorus dietary agents such as carbonated beverages and foods which are processed with phosphate salts (such as refrigerated doughs) may be useful alternatives.

Recent evidence indicates that women with a history of high blood pressure prior to becoming pregnant, as well as women with poor nutritional status should receive calcium carbonate supplements before and during pregnancy. Discuss this with your clinician before taking this supplement.

Avoid calcium supplements based on bone meal, dolomite or oyster shell because of the risk of lead contamination.