Decrease in Bone Mineral Density during Pregnancy and Change in Maternal Blood Lead Levels Open Access

Abstract

Abstract

Decrease in Bone Mineral Density during Pregnancy and Change in Maternal Blood Lead
Levels
Prenatal exposure to lead has been associated with spontaneous abortions, low birth
weight, and developmental delay. Lead stored in women's bones is released into their
blood during pregnancy. Maternal blood lead can cross the placenta and expose the
fetus. The purpose of this study is to examine the relation between change in bone
mineral density (BMD) and change in maternal blood lead levels across pregnancy.
Additionally, this study evaluated whether the association between changes in BMD
and blood lead is confounded by self-reported daily calcium intake. This was a
prospective study of 100 women who received prenatal care during the first 12 weeks
of pregnancy at Magee-Women's Hospital in Pittsburgh, Pennsylvania from October
1992 to February 1995. Change in maternal blood lead was calculated using the
difference between blood lead levels (μg/dL) measured, on average, at 17 and 37
weeks gestation. Change in BMD was calculated using the difference between
measurements of the ultra-distal BMD at 16 and 36 weeks gestation. Information
regarding sociodemographic and lifestyle factors was collected during interviews
between 8 and 18 weeks gestation and again between 31 and 41 weeks gestation. As
expected, maternal blood lead levels increased and ultra-distal BMD decreased during
pregnancy. However, change in BMD was weakly associated with change in maternal
blood lead levels during pregnancy (β = 0.33 μg/dL, 95% CI = -8.45, 7.80) in a linear
regression model adjusted for age, race, smoking, BMI, and calcium intake. Change
in blood lead was higher among women whose calcium intake was <1,000 mg/day
compared to 1,000-<2,000 mg/day. These findings suggest that the observed increase
in maternal blood lead during pregnancy may not be predominantly due to the
increased mobilization of bone lead as previously hypothesized. Further research on
the mechanisms that contribute to increased maternal blood lead during pregnancy is
needed.

Table of Contents

Table of Contents

Chapter Page

I: Background.................................................................................................................... 1
Introduction ..................................................................................................................... 1
Lead................................................................................................................................ 1
BMD ............................................................................................................................... 9
Conclusion ....................................................................................................................... 11
Table 1 ............................................................................................................................ 13
II: Decrease in Bone Mineral Density during Pregnancy and Change in Maternal Blood
Lead Levels ...................................................................................................................... 17
Introduction ..................................................................................................................... 18
Methods........................................................................................................................... 20
Results ............................................................................................................................ 23
Discussion ........................................................................................................................ 24
References ....................................................................................................................... 27
Table 1 ............................................................................................................................ 33
Table 2 ............................................................................................................................ 34
Table 3 ............................................................................................................................ 35
Figure ............................................................................................................................. 36
Appendix. IRB Letter of Exemption ........................................................................................ 37

About this Master's Thesis

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School	Rollins School of Public Health
Department	Epidemiology
Degree	MPH
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health
Keyword	lead pregnancy bone loss calcium
Committee Chair / Thesis Advisor	Howards, Penelope, Emory University
Partnering Agencies	Emory University schools, faculty or affiliated programs

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