Effects of various levels of dietary calcium during pregnancy on maternal calcium utilization and fetal growth in rats.

Abstract

SummaryThe effects of calcium-free and normal (0.6%) and high (1.0%) calcium diets on the transfer of calcium from pregnant mothers to fetuses were investigated by balance experiments. Pregnant rats receiving calcium-free, normal and high calcium diets ate totals of 353, 324 and 280g of the diet, respectively, during pregnancy, and the food con sumption of the latter two groups decreased near term. The group on calcium-free diet was able to maintain pregnancy and produce normal fetuses by using calcium resorbed from the dam's bones. The calcium retentions due to pregnancy in rats on normal and high calcium diets were 116 and 128 mg, respectively, during the first 15 days, and -9 and -109mg , respectively, during the last 6 days of pregnancy. Fetuses contained about 130mg of calcium at term and most of this calcium was supplied from the dam's bones, in which extra calcium were retained during early-mid pregnancy. Unexpectedly, the true rate of calcium absorption was appreciably lower during late pregnancy than during early-mid pregnancy in both dietary groups. Thus, extra calcium retention during early-mid pregnancy seemed to be physiological adaptation to a decrease in either food consumption or calcium absorption during late pregnancy. Phosphorus absorption and its balance were examined in relation with the dietary calcium levels.

Essential Metal Balance and Retention during the Second Half of Pregnancy in the Rat

“…The in creased calcium taken up from the diet is practically transferred to the fetus [23]. There is an increased calcium retention in the first half of pregnancy in the rat as an adaptation to the situation in the second half [7], when the overall retention is lower than in controls because of an important decrease in calcium uptake [7]. Here, there were no significant changes in calcium retention with respect to controls nor during the second half of pregnancy studied, with ample daily vari ations.…”

“…The availability of some mineral elements in the diet is critical for the adequate supply of the dam and her fetuses [ 1 ], and the lack of some elements in the diet in sufficient amounts results in severe deficiencies [2] such as ane mia [3,4], The actual balance of essential metals in pregnant animals has been studied for some metals [5][6][7], but only at term or in special situations [5], It has been intended here to follow daily the balance of 7 essential metals: calcium, copper, iron, magnesium, zinc, sodium and potassium during the sec ond half of pregnancy in the rat, in order to gain more knowledge about the possible changes in retention from the diet, as postu lated elsewhere [8]. We also tried to deter mine the effects of increased ingestion due to pregnancy [9] in the actual balance of these metals in a situtation where it is necessary to supply the growing needs of the fetuses [ 10].…”

Effects of lead exposure before pregnancy and dietary calcium during pregnancy on fetal development and lead accumulation.

“…West et al (18) found an inverse relationship between gestational age and maternal blood lead concentrations, but the latter did not differ significantly for birth weights > 2,500 g versus < 2,500 g. Studies in Kosovo (19,20) (23)(24)(25)(26). Because the skeleton is also the major repository for lead, mobilization of skeletal lead and calcium occurs simultaneously when dietary calcium intake during pregnancy is inadequate.…”

Influence of moderate food restriction on calcium metabolism in pregnant rats

“…Nevertheless, these metabolites are not involved in the control of fetal serum calcium, possibly because of the relatively large influx of 1,25(OH) 2 D 3 . Nev-ertheless, these metabolites are not involved in the control of fetal serum calcium, possibly because of the relatively large influx of 1,25(OH) 2 D 3 across the placenta from both maternal synthesis and placental production (Danan et al, 1982;Stevenson, 1983 (Graves and Wolinski, 1980;Toraason, 1983), d 20 (Halloran and DeLuca, 1980b) or at other times (Chef, 1969;Lai et al, 1984).…”