Calcification density in single and twin placenta villi

Placentas are temporary organs needed to support a developing embryo and arise from both embryonic and maternal tissues. Calcifications of tissues outside of bone and teeth mineralization are often a sign of tissue damage and impaired organ function. Placental calcifications have been described previously in the literature and usually increase in normal pregnancies as the placenta ages, but they have also been associated with the potential for fetal distress. This study utilized 139 placental tissues from singleton control placentas (51), fused twin placentas (48), and non-fused twin placentas (40) with weights over 320 grams (third trimester) and similar maternal ages to determine which placental type(s) exhibited the largest density of calcifications using the von Kossa stain for calcium salts. The study found there were no differences in calcification densities among placenta types, suggesting that twin pregnancies do not experience additional placental stress risk from calcifications. Importantly, the finding that nearly all third-trimester placentas contained calcifications when systematically evaluated indicates that calcification may represent a normal maturational process rather than a pathologic sign of distress. These results help to caution the interpretation of placental calcifications and may provide reassurance to patients and providers managing twin pregnancies.