Fetal Bone Formation Is Decreased from Middle Pregnancy to Birth

Abstract

Fetal bone development is a complex process that is regulated and maintained by minerals, hormones, and growth factors delivered from the mother via the placenta. Various biochemical markers of fetal bone development have been identified. However, many aspects of this process remain unclear. The aim of the study was to measure the activities of serum tartrate-resistant acid phosphatase type 5b (TRACP 5b) as a bone resorption marker and bone alkaline phosphatase (BAP) as a bone formation marker in preterm and term neonates, and to investigate fetal bone development in middle and late pregnancy. The study included 111 neonates (87 preterm and 24 term) born at Dokkyo Medical University Hospital. Neonates with illnesses and maternal diseases were excluded. Serum samples were collected within 3 hours after birth and stored at −80°C. Univariate and multivariate linear regression analyses were performed. The 111 neonates (median birth weight, 1,510 g) were born at a median of 31.3 weeks of gestation, and had TRACP 5b and BAP activities of 10.9 ± 4.0 U/L and 127.5 ± 49.2 U/L, respectively. TRACP 5b activity showed a tendency to be higher in term neonates, while BAP activity tended to be lower in term neonates. Importantly, TRACP 5b activity was positively correlated with gestational age and birth weight, and BAP activity was negatively correlated with gestational age, rate of born small-for-gestational-age neonates, and birth weight. These results suggest that bone formation during fetal growth is gradually decreased from middle pregnancy to birth, whereas bone resorption is gradually increased.Keywords: bone alkaline phosphatase; fetal bone development; preterm neonate; tartrate-resistant acid phosphatase type 5b; term neonate Tohoku J.

Discordant responses of bone formation and absorption markers in Japanese infants with vitamin D deficiency: a comprehensive matched case–control study

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“…TRACP-5b was determined by EIA (Osteolinks ®TRAP-5b; Nittobo Medical Co., Ltd.). 18 Serum NTx concentrations were evaluated by the OSTEOMARK® NTx serum competitive-inhibition enzyme-linked immunosorbent assay (Abbott Diagnostics Medical Co.). 19 Serum calcium, magnesium, and inorganic phosphorus levels were measured by a method widely used in Japan.…”

Changes in Serum Concentrations of Bone Turnover Markers in Healthy Pregnant Women

“…During fetal growth from middle pregnancy to birth, TRACP 5b activity gradually decreased. In contrast, BAP activity steadily increased [ 36 ], which may lead to increased ALP in the mother.…”