J Bone Miner Res, 2021; 36(7): 1269-1280, PMID: 33784438

Pregnancy-related change in pQCT and bone biochemistry in a population with a habitually low calcium intake.

Year: 2021

Breasail MO, Ward KA, Schoenbuchner SM, Ceesay M, Mendy M, Jarjou LM, Moore SE, Prentice A
MRC Nutrition and Bone Health Research Group, Clifford Allbutt Building, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 OAH.

Abstract

In pregnancy, changes in maternal calcium (Ca) economy occur to satisfy fetal Ca demand. It is unclear whether maternal mineral reserves facilitate these requirements and no data exist from sub-Saharan Africa. The aim was to determine skeletal changes with pQCT and bone biochemistry between early second and third trimesters. Pregnant rural Gambians aged 18-45 years (n = 467) participating in a trial of antenatal nutritional supplements (ISRCTN49285450) had pQCT scans and blood collections at mean(SD) 14 (3) and 31 (1) weeks gestation. Outcomes were pQCT: radius/tibia 4% total vBMD, trabecular vBMD, total CSA, 33%/38% radius/tibia cortical vBMD, BMC, total CSA; biochemistry: collagen type 1 cross-linked beta-C-telopeptide (beta-CTX), type 1 procollagen N-terminal (P1NP), parathyroid hormone (PTH) and 1,25(OH)2 D. Independent t-tests tested whether pooled or within-group changes differed from 0. Multiple regression were performed adjusting for age. Data for change are expressed as mean[CI 2.5, 97.5]%. Radius trabecular vBMD, cortical vBMD and BMC increased by 1.15 [0.55, 1.75]%, 0.41 [0.24, 0.58]%, and 0.47 [0.25, 0.69]%. Tibia total and trabecular vBMD increased by 0.34 [0.15, 0.54]% and 0.46 [0.17, 0.74]%, while tibia cortical vBMD, BMC, and cortical CSA increased by 0.35 [0.26, 0.44]%, 0.55 [0.41, 0.68]% and 0.20 [0.09, 0.31]% respectively. CTX, PTH and 1,25(OH)2 D increased by 23.0 [15.09, 29.29]%, 13.2 [8.44, 19.34]%, and 21.0 [17.67, 24.29]%, while P1NP decreased by 32.4 [-37.19, -28.17]%. No evidence of mobilization was observed in the peripheral skeleton. Resorption, while higher in late- versus early-gestation, was lower throughout pregnancy compared to non-pregnant non-lactating (NPNL) in the same community. Formation was lower in late pregnancy than in early, and below NPNL levels. This suggests a shift in the ratio of resorption to formation. Despite some evidence of change in bone metabolism, in this population, with habitually low Ca intakes, the peripheral skeleton was not mobilized as a Ca source for the fetus.

GID: 5341; Last update: 06.04.2021