published_or_final_version / Community Medicine / Master / Master of Public Health

published_or_final_version / Community Medicine / Master / Master of Public Health

published_or_final_version / Nursing Studies / Master / Master of Nursing in Advanced Practice

該前瞻性研究對香港中國裔孕婦的25羥基維生素D（25（OH）D）的水平及其影響因素進行調查，并對25（OH）D與甲狀旁腺激素（PTH）、孕期肌肉酸痛、不良妊娠結局、孕期及産後骨質流失，以及嬰兒的骨骼發育等關係進行探索，力求建立適用于香港的中國孕婦的25（OH）D正常值。 / 共有237名單胎妊娠婦女以及62名多胎妊娠的婦女在2010年8月至2011年11月間參加本研究中的隊列研究，分別在參加研究時（<20 孕周）、24-28孕周、31-36孕周以及産後6-11周進行抽血測量血清25（OH）D以及PTH水平，同時填寫一份包括對每月攝取含維生素D的食物以及營養補充劑頻度、接受日照情況及喜好、以及肌肉不適等情況的問卷，并在24-28孕周進行75克口服葡萄糖耐量試驗。參與隊列研究的單胎孕婦在20周前、31-36孕周以及産後隨訪時接受用定量超聲測量非優勢手的橈骨遠端以及中指近掌指骨的骨質超聲速率（SoS）。在産後複查時，對其嬰兒左側腓骨中部的骨質SoS進行測量。記錄婦女各次檢查時的體重、抽血月份紫外線輻射強度的歷史記錄、以及妊娠結局。另外募集一批孕婦參加病例對照研究，比較患早產（PTB）、子癇前期（PET）、妊娠糖尿病 （GDM）以及胎兒生長受限（FGR）併發癥的婦女與對照組 （體重指數以及抽血時紫外線強度配對）的血清25（OH）D水平。 / 孕婦在孕期的平均25（OH）D水平在44.7 ± 12.6 至48.9 ± 17.1 nmol/l範圍，25（OH）D水平與體重指數、維生素D營養補充劑、抽血時紫外線強度以及個人對陽光的喜好情況有關，而與胎兒數量、孕次、孕周以及終止妊娠無關。 / 單胎妊娠的孕婦三個孕期的血清25（OH）D與PTH水平均負相關，但在多胎妊娠中，二者無明顯相關性。PTH在孕期以及産後的變化相對不受25（OH）D影響。孕婦25（OH）D的水平與孕婦肌肉酸痛癥狀、産後恢復、孕期及產褥期骨質流失以及嬰兒骨質無關。患早期PTB（< 34孕周）、PET或FGR的孕婦的血清25（OH）D比對照組低，但GDM患者的25（OH）D水平與對照組無差別。血清25（OH）D低於34.3 nmol/l者的早期早產以及子癇前期的風險增高，低於50 nmol/l者發生胎兒生長受限的風險增高。服用維生素D補充劑情況可能影響25（OH）D與FGR的關係。 / 總而言之，血清25（OH）D水平不足以全面完全反映孕期維生素D的情況，對預測不良妊娠結局的作用有限。 / This prospective study explored the maternal serum level of 25(OH)D in Chinese pregnant women in Hong Kong and the factors affecting 25(OH)D level. It also explored the correlation between maternal 25(OH)D with PTH level, maternal musculoskeletal complaints, adverse pregnancy outcome, maternal bone turnover during pregnancy and postpartum, and the bone development of the offspring, aiming to explore and establish a normal range of 25(OH)D level in pregnancy for the Hong Kong Chinese women. / A total of 237 women with singleton pregnancy and 62 women with multiple pregnancies were recruited for the cohort study from August, 2010 to November, 2011. Maternal blood samplings for 25(OH)D and PTH measurements were performed at recruitment, 24-28 weeks, 31-36 weeks of gestation, and 6-11 weeks postpartum respectively. A questionnaire which included the monthly dietary and supplement intake of vitamin D, questions about sunlight exposure, and musculoskeletal complaints was administered on each visit. A 75g oral glucose tolerance test (OGTT) was performed on cohort cases at 24-28 weeks of gestation. Measurements of the speed of sound (SoS) at the distal one third of the maternal radius and the proximal phalanx of the third finger of the non-dominant side were performed with quantitative ultrasonography (QUS) measurement during the visits at the first and third trimesters, and postnatal period. The SoS at the left mid-shaft tibia of the offspring was determined during the postnatal visit. Maternal characteristics, ultraviolet radiation (UVR) intensity at blood sampling, and pregnancy outcome, were also recorded. Cases with pregnancy complications were recruited for case-control studies, and maternal 25(OH)D level was examined with respect to preterm birth (PTB), preeclampsia (PET), gestational diabetes (GDM), and fetal growth restriction (FGR, birthweight below the 10th percentile of the customized estimated birthweight). The controls were matched for booking body mass index (BMI) and UVR intensity at blood sampling. / The mean 25(OH)D level in ranged from 44.7 ± 12.6 to 48.9 ± 17.1 nmol/l in the three trimesters, and was related to BMI, vitamin D supplementation, UVR intensity at blood sampling, and the acceptance of sunlight exposure, but not the number of fetus, parity, gestational age, or the completion of pregnancy. / Inverse correlation between PTH and 25(OH)D were observed in singleton, but not in multiple, pregnancy. The change in maternal PTH level is found to be relatively independent from that of 25(OH)D. There was no correlation between maternal 25(OH)D level with musculoskeletal complaints, postnatal recovery, bone turnover during and after pregnancy, or the bone density of the offspring. Maternal 25(OH)D level was lower in women with early PTB ( < 34 weeks), PET, and FGR, but not for GDM. A maternal 25(OH)D level of lower than 34.3nmol/l and 50 nmol/l was associated with increased risk of early PTB, PET, and FGR respectively. But the correlation between maternal 25(OH)D level with FGR might be affected by supplementation. / In conclusion, serum level of 25(OH)D is insufficient in reflecting maternal vitamin D status and metabolism in pregnancy, and is of limited use in predicting adverse pregnancy outcome. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Hu, Zhiyang. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2013. / Includes bibliographical references (leaves 201-223). / Abstracts and appendixes also in Chinese. / Thesis dedication --- p.i / Acknowledgments --- p.ii / Abstract --- p.v / Abstract (Chinese) --- p.viii / List of Abbreviation --- p.x / Table of contents --- p.xiii / List of Figures --- p.xxii / List of Tables --- p.xxiv / Chapter Chapter 1: --- Literature Review --- p.1 / Chapter 1.1 --- The synthesis and metabolism of vitamin D --- p.3 / Chapter 1.1.1 --- The synthesis of vitamin D --- p.3 / Chapter 1.1.2 --- The metabolism of vitamin D --- p.4 / Chapter 1.1.3 --- Vitamin D binding protein --- p.10 / Chapter 1.1.4 --- Factors related to 25(OH)D level --- p.11 / Chapter 1.2 --- Function of vitamin D --- p.13 / Chapter 1.2.1 --- Mechanism of vitamin D function --- p.13 / Chapter 1.2.2 --- Classic function --- p.14 / Chapter 1.2.3 --- Non-classic function --- p.16 / Chapter 1.2.3.1 --- Immune system --- p.17 / Chapter 1.2.3.2 --- Cardiovascular system --- p.18 / Chapter 1.2.3.3 --- Cell proliferation and differentiation --- p.18 / Chapter 1.2.3.4 --- Neurological system --- p.19 / Chapter 1.2.3.5 --- Reproductive system --- p.20 / Chapter 1.2.3.6 --- Fetal development --- p.21 / Chapter 1.3 --- The definition of vitamin D deficiency --- p.21 / Chapter 1.4 --- Vitamin D status and pregnancy --- p.24 / Chapter 1.4.1 --- Alteration in vitamin D metabolism during pregnancy --- p.24 / Chapter 1.4.2 --- Factors affecting maternal serum level of 25(OH)D --- p.25 / Chapter 1.4.3 --- Vitamin D and bone resorption during pregnancy and lactation --- p.27 / Chapter 1.4.3.1 --- Alteration of calcium metabolism, bone absorption and the role of vitamin D --- p.27 / Chapter 1.4.3.2 --- Measurement of bone density in pregnant women and babies --- p.33 / Chapter 1.4.4 --- Current studies on maternal vitamin D status and pregnancy outcome --- p.35 / Chapter 1.4.4.1 --- Birthweight --- p.35 / Chapter 1.4.4.2 --- Infection --- p.37 / Chapter 1.4.4.3 --- Preterm delivery --- p.39 / Chapter 1.4.4.4 --- Diabetes (DM) and gestational diabetes (GDM) --- p.39 / Chapter 1.4.4.5 --- Hypertension and preeclampsia --- p.41 / Chapter 1.4.4.6 --- Multiple pregnancy, muscular symptoms --- p.42 / Chapter 1.4.4.7 --- Vitamin D supplementation and pregnancy outcome --- p.44 / Chapter 1.5 --- Defining vitamin D deficiency in pregnancy --- p.45 / Chapter 1.6 --- Objective of the study --- p.46 / Chapter Chapter 2: --- Study design and methods --- p.48 / Chapter 2.1 --- Case recruitment and study design --- p.48 / Chapter 2.1.1 --- Longitudinal singleton study --- p.49 / Chapter 2.1.2 --- Cross-sectional study --- p.50 / Chapter 2.1.2.1 --- Preterm birth (PTB) --- p.51 / Chapter 2.1.2.2 --- Preeclampsia (PET) --- p.51 / Chapter 2.1.2.3 --- Gestational diabetes (GDM) --- p.52 / Chapter 2.1.3 --- Multiple pregnancy study --- p.52 / Chapter 2.2 --- Measurements --- p.53 / Chapter 2.2.1 --- Hormonal analysis of serum levels of 25(OH)D and PTH --- p.53 / Chapter 2.2.2 --- Calculation of monthly intake of vitamin D from diet --- p.55 / Chapter 2.2.3 --- SoS measurements --- p.56 / Chapter 2.2.4 --- Ultraviolet radiation strength assessment --- p.59 / Chapter 2.3 --- Statistical analysis --- p.60 / Chapter Chapter 3 --- Longitudinal Study on the Level of and Factors Affecting Vitamin D in Singleton Pregnancy --- p.62 / Chapter 3.1 --- Introduction --- p.62 / Chapter 3.2 --- Material and method --- p.63 / Chapter 3.3 --- Statistics --- p.64 / Chapter 3.4 --- Results --- p.65 / Chapter 3.4.1 --- Demographic data of the subjects --- p.65 / Chapter 3.4.2 --- Maternal levels of 25(OH)D and PTH, and the factors affecting their levels --- p.66 / Chapter 3.4.2.1 --- Distribution of 25(OH)D level and PTH level in the four visits --- p.66 / Chapter 3.4.2.2 --- Dietary intake of vitamin D and supplementation --- p.69 / Chapter 3.4.2.3 --- Seasonality and sunlight exposure --- p.73 / Chapter 3.4.2.4 --- Parity --- p.76 / Chapter 3.4.3 --- Changes of maternal levels of 25(OH)D and PTH in pregnancy --- p.78 / Chapter 3.4.4 --- Independent factors related to maternal 25(OH)D level in pregnancy --- p.79 / Chapter 3.4.5 --- Maternal and fetal 25(OH)D level at delivery --- p.80 / Chapter 3.4.6 --- Muscular symptoms and other complaints in pregnancy, pregnancy outcome, and their relationships with maternal 25(OH)D level --- p.81 / Chapter 3.4.7 --- Postnatal recovery and factors related to postnatal level of 25(OH)D and PTH --- p.86 / Chapter 3.4.7.1 --- Postnatal symptoms and relationship with 25(OH)D and PTH --- p.86 / Chapter 3.4.7.2 --- The postnatal level of 25(OH)D and PTH in women with different feeding mode --- p.88 / Chapter 3.4.7.3 --- Independent factors related to postnatal 25(OH)D and PTH level --- p.89 / Chapter 3.4.7.4 --- Factors related to the change of 25(OH)D and PTH after delivery --- p.90 / Chapter 3.4.8 --- Correlation between 25(OH)D with PTH in pregnancy and postnatal period --- p.91 / Chapter 3.5 --- Discussion --- p.92 / Chapter 3.5.1 --- 25(OH)D level in Chinese pregnant women --- p.92 / Chapter 3.5.2 --- Factors related to maternal 25(OH)D level --- p.93 / Chapter 3.5.2.1 --- Dietary and supplementation --- p.93 / Chapter 3.5.2.2 --- Seasonality and outdoor activity --- p.96 / Chapter 3.5.2.3 --- Gestational age --- p.98 / Chapter 3.5.2.4 --- Age and parity --- p.98 / Chapter 3.5.3 --- Relationship of 25(OH)D level in the cord blood with maternal 25(OH)D level --- p.99 / Chapter 3.5.4 --- 25(OH)D level and muscular complains in pregnancy --- p.100 / Chapter 3.5.5. --- Postnatal recovery and 25(OH)D level --- p.101 / Chapter 3.5.6 --- PTH level in pregnancy and postnatal period --- p.101 / Chapter 3.6 --- Conclusion --- p.102 / Chapter Chapter 4 --- Longitudinal Study on the Relationship between Maternal 25(OH)D level with Changes of Maternal Bone Density in Pregnancy and Lactation, and Factors Affecting Bone Density of newborn Infants --- p.105 / Chapter 4.1 --- Introduction --- p.105 / Chapter 4.2 --- Material and method --- p.106 / Chapter 4.3 --- Statistics --- p.108 / Chapter 4.4 --- Results --- p.108 / Chapter 4.4.1 --- Demographic data --- p.108 / Chapter 4.4.2 --- Maternal bone density and the changes in pregnancy and postnatal recovery --- p.109 / Chapter 4.4.2.1 --- Maternal bone density in the first trimester and related factors --- p.109 / Chapter 4.4.2.2 --- Maternal bone density in the three visits --- p.109 / Chapter 4.4.2.3 --- The change in maternal bone density in the three visits --- p.110 / Chapter 4.4.2.4 --- Diversity in the change of bone density in pregnant women --- p.112 / Chapter 4.4.3 --- Factors related to the changes in bone density --- p.114 / Chapter 4.4.3.1 --- Changes between the first and the third trimesters --- p.114 / Chapter 4.4.3.2 --- Change between the third trimester and postnatal visits --- p.116 / Chapter 4.4.4 --- The bone density in infants and related factors --- p.120 / Chapter 4.5 --- Discussion --- p.122 / Chapter 4.5.1 --- Maternal bone density changes in pregnancy and postnatal period --- p.122 / Chapter 4.5.2 --- Factors related to the maternal bone density changes in pregnancy and postnatal period --- p.124 / Chapter 4.5.2.1 --- Initial bone density, parity, and BMI --- p.125 / Chapter 4.5.2.2 --- 25(OH)D and PTH level --- p.126 / Chapter 4.5.2.3 --- Supplement --- p.127 / Chapter 4.5.2.4 --- Lactation --- p.128 / Chapter 4.5.2.5 --- Height --- p.129 / Chapter 4.5.3 --- Factors related to bone density of the infant. --- p.130 / Chapter 4.5.3.1 --- Maternal 25(OH)D level --- p.130 / Chapter 4.5.3.2 --- Gestational age and birthweight --- p.131 / Chapter 4.5.3.3 --- Maternal bone density change --- p.131 / Chapter 4.5.3.4 --- The gender of the offspring and feeding method --- p.132 / Chapter 4.6 --- Conclusion --- p.133 / Chapter Chapter 5 --- Maternal 25(OH)D Level in Multiple Pregnancy --- p.134 / Chapter 5.1 --- Introduction --- p.134 / Chapter 5.2 --- Material and method --- p.135 / Chapter 5.3 --- Statistics --- p.136 / Chapter 5.4 --- Results --- p.137 / Chapter 5.4.1 --- Demographic data of the subjects --- p.137 / Chapter 5.4.2 --- The level of 25(OH)D in multiple pregnancy and singleton pregnancy --- p.137 / Chapter 5.4.3 --- Supplementation in multiple pregnancy --- p.140 / Chapter 5.4.4 --- The change of maternal 25(OH)D and PTH levels in the three trimesters --- p.141 / Chapter 5.4.5 --- 25(OH)D level in cord blood and its correlation with 25(OH)D level of the sibling --- p.143 / Chapter 5.4.6 --- Correlation between 25(OH) with PTH in pregnancy --- p.143 / Chapter 5.5 --- Discussion --- p.144 / Chapter 5.5.1 --- 25(OH)D level in multiple pregnancy and singleton pregnancy --- p.144 / Chapter 5.5.2 --- Supplementation in multiple pregnancy --- p.146 / Chapter 5.5.3 --- Changes of maternal levels of 25(OH)D and PTH in the three trimesters in multiple pregnancy --- p.146 / Chapter 5.5.4 --- The PTH/25(OH) correlation --- p.147 / Chapter 5.6 --- Conclusion --- p.148 / Chapter Chapter 6 --- Maternal level of 25(OH)D in complicated pregnancy --- p.150 / Chapter 6.1 --- Introduction --- p.150 / Chapter 6.2 --- Method --- p.153 / Chapter 6.2.1 --- Preterm birth --- p.155 / Chapter 6.2.2 --- Preeclampsia --- p.155 / Chapter 6.2.3 --- Gestational diabetes --- p.156 / Chapter 6.2.4 --- Fetal growth restriction --- p.157 / Chapter 6.2.5 --- The association between 25(OH)D level with pregnancy complication --- p.158 / Chapter 6.3 --- Statistics --- p.159 / Chapter 6.4 --- Results --- p.160 / Chapter 6.4.1 --- Setting of the cutoff values of hypovitaminosis D --- p.160 / Chapter 6.4.2 --- Preterm birth --- p.160 / Chapter 6.4.3 --- Preeclampsia --- p.164 / Chapter 6.4.4 --- Gestational diabetes --- p.168 / Chapter 6.4.4.1 --- Case-control study --- p.168 / Chapter 6.4.4.2 --- Factors affecting OGTT results --- p.170 / Chapter 6.4.5 --- Fetal growth restriction --- p.173 / Chapter 6.5 --- Discussion --- p.179 / Chapter 6.5.1 --- Adjustment for confounders for case-control study --- p.179 / Chapter 6.5.2 --- PTB and 25(OH)D level --- p.181 / Chapter 6.5.3 --- PET and 25(OH)D level --- p.182 / Chapter 6.5.4 --- GDM and 25(OH)D level --- p.186 / Chapter 6.5.5 --- FGR and 25(OH)D level --- p.189 / Chapter 6.5.6 --- Defining vitamin D deficiency in pregnancy --- p.192 / Chapter 6.6 --- Conclusion --- p.195 / Chapter Chapter 7 --- Summary --- p.196 / References --- p.201 / Chapter Appendix 1 --- Antenatal questionnaire (English/Chinese) --- p.224 / Chapter Appendix 2 --- Postnatal questionnaire (English/Chinese) --- p.238