Lack of correlation between first trimester maternal serum 25-hydroxyvitamin D levels and ultrasound measured crown-rump length and nuchal translucency

The Gestational Effects of Maternal Bone Marker Molecules on Fetal Growth, Metabolism and Long-Term Metabolic Health: A Systematic Review

Fetal exposure in adverse environmental factors during intrauterine life can lead to various biological adjustments, affecting not only in utero development of the conceptus, but also its later metabolic and endocrine wellbeing. During human gestation, maternal bone turnover increases, as reflected by molecules involved in bone metabolism, such as vitamin D, osteocalcin, sclerostin, sRANKL, and osteoprotegerin; however, recent studies support their emerging role in endocrine functions and glucose homeostasis regulation. Herein, we sought to systematically review current knowledge on the effects of aforementioned maternal bone biomarkers during pregnancy on fetal intrauterine growth and metabolism, neonatal anthropometric measures at birth, as well as on future endocrine and metabolic wellbeing of the offspring. A growing body of literature converges on the view that maternal bone turnover is likely implicated in fetal growth, and at least to some extent, in neonatal and childhood body composition and metabolic wellbeing. Maternal sclerostin and sRANKL are positively linked with fetal abdominal circumference and subcutaneous fat deposition, contributing to greater birthweights. Vitamin D deficiency correlates with lower birthweights, while research is still needed on intrauterine fetal metabolism, as well as on vitamin D dosing supplementation during pregnancy, to diminish the risks of low birthweight or SGA neonates in high-risk populations.

Diet in pregnant women that delivered prematurely and preterm newborn's bone status

OBJECTIVES

Inadequate maternal dietary pattern has been associated to negative pregnancy and fetal outcomes. With this study, we aimed to evaluate the adequacy of diet in pregnant women that delivered prematurely and its possible correlations with bone status of preterm newborns.

STUDY DESIGN

We prospectively enrolled women who delivered prematurely (≤than 34 gestational weeks) and their newborns (Neonatal Intensive Care, University Hospital of Padova) from January 2017 to May 2018. Maternal nutritional status and diet supplementations were assessed using a validated questionnaire. The preterm newborns were evaluated with anthropometric measurements and bone status by Quantitative Ultrasound of the second metacarpal bone within 72 h from birth.

RESULTS

One hundred and eighty mothers and 202 preterm newborns were evaluated. The mothers assumed more calories, proteins, total lipids and simple sugars compared to the revised National Guidelines. The intake of calcium, phosphorus and Vitamin D was inadequate despite the use of multivitamin supplements. The mothers assumption of vitamin D and zinc positively correlated with bone status and mothers with very low intake of vitamin D during gestation (<7 µg/die) had preterm newborns with a worst bone status at birth compared to those with a better intake (>7 µg/die).

CONCLUSIONS

Nutrition of pregnant women could be improved and maternal intakes of Vitamin D and zinc positively correlated with preterm newborn's bone status.

Maternal and child factors associated with bone length traits in children at 3 years of age

BACKGROUND

Exposure to sub-optimal maternal vitamin D status during pregnancy has been linked to inadequate in utero bone growth with potential for post-natal deficits, but reported findings are inconsistent. Possible reasons include measurement error in assessing bone length/height, or lack of adjustment for confounding variables such as maternal/infant diet, physical activity and season of birth. The objective of this study was to determine the maternal and child factors associated with bone length traits in children at 3 years of age as part of a longitudinal follow-up of a pregnancy cohort.

METHODS

Mother-child dyads enrolled in the Family Atherosclerosis Monitoring In early Life study were included. Maternal serum 25-hydroxyvitamin D (25(OH)D) concentration was measured by liquid chromatography tandem mass spectrometry (LC-MS/MS). Anthropometry, physical activity by questionnaire and dietary assessment by food frequency questionnaire were completed for mothers during pregnancy (27-40 weeks gestation) and for children at 3 years with diet by 3-day food records (Nutritionist Pro). Whole body bone mineral density in mother and child (n = 473) was measured by dual-energy absorptiometry (DXA) at the 3 year visit. A software program was developed using MATLAB to derive bone length measurements from whole body DXA images using 8 long bones of each child. Association between maternal and child variables with offspring bone length was assessed using unadjusted and adjusted multivariate linear regression analyses.

RESULTS

In the final adjusted multivariate regression model, factors associated with child bone length were maternal height (p = 0.05), child birth length (p = 0.005) and child weight z-score at 3 years (p < 0.001). No association was observed between maternal serum 25(OH)D concentrations in pregnancy (of which 77% were in normal range) and child bone length.

CONCLUSION

In healthy Canadian mothers and their children, the factors associated with child bone length achieved at 3 years of age appear to be related to genetic traits rather than environmental exposures. Measures of the length of long bones in children using DXA scans may have provided a more accurate assessment of bone length than whole body height measures.

Positive effect of low dose vitamin D supplementation on growth of fetal bones: A randomized prospective study

The effect of vitamin D supplementation on growth of fetal bones during pregnancy is unclear. The aim of this study was to assess the effect of low dose vitamin D supplementation during pregnancy on bony anthropometric aspects of the fetus. In this prospective randomized trial, 140 patients were divided into two equally matched groups according to age, 25(OH)D level, exercise, and dietary intake. Then 1000 IU per day vitamin D supplement was given to the intervention group while the control group received placebo. Then crown-rump length (CRL) and femur length (FL) during the first trimester and humerus and femur lengths as well as their proximal metaphyseal diameter (PMD), midshaft diameter (MSD) and distal metaphyseal diameter (DMD) in the second and third trimester were measured using ultrasonography technique. Finally, no significant difference was observed for CRL (p = 0.93). Although FL was not statistically significant in the first trimester (p = 0.54), its measurement in the intervention group and the control group in the second (28.87 ± 2.14 vs. 26.89 ± 2.08; p ≤0.001) and the third (65.31 ± 2.17 vs. 62.85 ± 1.94; p ≤0.001) trimesters was significantly different. Femoral PMD, MSD, and DMD measurement increased more in the intervention group in comparison with the control group with P values <0.05. HL measurement in the intervention group and the control group in the second (28.62 ± 1.94 vs. 27.23 ± 2.08; p ≤0.001) and the third (61.29 ± 2.84 vs. 59.85 ± 1.79; p ≤0.001) trimesters revealed significant differences. Humeral PMD, MSD, and DMD measurement increased in the intervention group in comparison with the control group with P values <0.001 for all. It is suggested to prescribe low dose vitamin D (1000 IU per day) from early pregnancy with possible increment in length and diameter of femur and humerus bones of the fetus.

Maternal vitamin D levels during pregnancy and neonatal health: evidence to date and clinical implications

Low maternal vitamin D levels during pregnancy have been associated with a plethora of adverse neonatal outcomes, including small for gestational age and preterm births, detrimental effect on offspring bone and teeth development, and risk of infectious diseases. Although most observational studies indicate a significant linear relationship between maternal 25-hydroxyvitamin D and the above outcomes, some randomized controlled trials to date are inconclusive, mostly due to differences in study design and supplementation regimen. The currently available results indicate that vitamin D supplementation during pregnancy reduces the risk of preterm birth, low birth weight, dental caries of infancy, and neonatal infectious diseases such as respiratory infections and sepsis. This narrative review aims to summarize available trial results regarding the effect of low maternal vitamin D levels during pregnancy, in conjunction with neonatal outcomes on the field, with a discourse on the appropriate clinical approach of this important issue.

Maternal 25-hydroxyvitamin D level and fetal bone growth assessed by ultrasound: a systematic review

OBJECTIVES

To assess systematically the role of maternal vitamin D levels in fetal bone growth.

METHODS

PubMed, EMBASE and Cochrane databases were searched using the search words [Vitamin D] in combination with [fetal, fetus, intrauterine, or prenatal AND growth, development, bone, femur, or humerus]; [crown-rump length]; or [ultrasonography, prenatal]. Criteria for inclusion in this systematic review were data on maternal serum 25-hydroxyvitamin D (25(OH)D) during pregnancy and measurement of fetal growth by ultrasound.

RESULTS

We identified 750 publications initially, from which five observational studies were selected for inclusion in the final review. The parameters studied were humerus length (HL) and femur length (FL) and their Z-scores, femoral volume, femoral distal metaphyseal cross-sectional area (CSA), femoral proximal metaphyseal diameter (PMD), femoral mid-shaft diameter and crown-rump length. In one study, 25(OH)D was associated directly with FL; in another study 25(OH)D only correlated with FL and HL Z-scores when calcium intake was insufficient. Two studies found no association between 25(OH)D and FL, but detected a direct association with femoral PMD, and an inverse relation with femoral distal metaphyseal CSA, respectively.

CONCLUSIONS

Observational studies investigating the role of maternal vitamin D levels in fetal bone growth are sparse. Their evidence suggests that low maternal 25(OH)D levels may affect fetal bone growth under certain circumstances, especially in cases of simultaneous low calcium intake. Further studies are necessary.