During your pregnancy, you need more vitamins and minerals than you do at other times. While your developing baby doesn't yet depend upon a large quantity of available calcium at just 5 weeks of gestational age, it's still a good idea to start increasing your calcium reserves early in pregnancy, so that you're prepared for the time -- just a few months away -- when your baby grows larger and its demands increase. Oyster shell calcium is one inexpensive source of calcium, but it has some drawbacks.
Pregnancy
In general, it's a good idea to take all the vitamins and minerals that you'll need for a healthy pregnancy on a regular basis, and throughout your entire pregnancy. Some vitamins and minerals are more important to the early days and weeks of pregnancy -- folic acid is one example -- while others, including iron and calcium, become more important later on. At 5 weeks pregnant, your developing embryo is just beginning to form its skeletal system, notes AmericanPregnancy.org.
Calcium Supplements
There are many kinds of calcium available in pill form. None of these contain elemental, or metallic, calcium -- instead, they're all salts of various sorts. A calcium salt consists of a positively charged particle of calcium and a negatively charged particle of variable identity, where the type of calcium depends upon the identity of the negatively charged particle. The negatively charged particle in a calcium salt affects your body's ability to take up calcium from a supplement, but doesn't affect the activity of the calcium once it's been absorbed.
Oyster Shell Calcium
Specifically, oyster shell calcium is calcium carbonate, one of the least soluble of the calcium salts. This is the same kind of calcium salt you take in if you use Tums as a calcium supplement, though the source of oyster shell calcium is, quite specifically, crushed oyster shells. While the acidic interior of the stomach makes calcium carbonate a bit more soluble -- and a bit easier to absorb -- than it is in pure water, you nevertheless don't benefit as much from a given quantity of oyster shell calcium as you would from a similar quantity of calcium citrate or calcium lactate.
Other Concerns
Since oyster shell calcium comes from a natural source, it's more likely than some other calcium supplements to be contaminated with non-calcium metals. For example, a 2000 article published in the scholarly journal "Environmental Health Perspectives" notes that many samples of oyster shell calcium can contain lead contamination. Lead is a neurotoxin, meaning it damages the brain and nervous system. Since these systems are very sensitive in a developing baby, it may be advisable to avoid oyster shell calcium in favor of a different source of calcium during pregnancy.
References
- AmericanPregnancy.org: Five Weeks Pregnant
- "Environmental Health Perspectives"; Lead in Calcium Supplements; G Scelfo et al; April 2000
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