Doctoral Dissertations

Date of Award

6-1987

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Major

Human Ecology

Major Professor

Roy E. Beauchene

Committee Members

James K. Miller, Jane R. Savage, Mary Nelle Traylor

Abstract

There is evidence that magnesium (Mg) participates in blood pressure regulation and it has been proposed that Mg depletion may play a role in the development of pregnancy induced hypertension (PIH). To test these hypotheses, erythrocyte Mg, plasma Mg, and blood pressures of 53 nulliparous teenagers (age ≤ 20 years) were studied. Blood samples were collected monthly, and Mg content was determined by atomic absorption spectrophotometry. Monthly interviews and medical chart reviews were used to collect socioeconomic data and information on complications and use of supplements, medicines, alcohol, and tobacco. Pregnancy outcomes included 30 normal full-term deliveries (Normal group) and 12 subjects who developed PIH (PIH group). Plasma and erythrocyte Mg levels did not differ significantly between PIH and Normal groups. Overall, mean arterial blood pressure (MAP) was not significantly related to either plasma or erythrocyte Mg values. For the PIH group alone, there was a slight but significant (P < 0.05) inverse relationship between MAP and plasma Mg. PIH subjects reported more alcohol use than did Normal subjects (P < 0.02) but the 2 groups were similar for socioeconomic characteristics, gynecologic age (GA), previous oral contraceptive pill use, use of Mg-containing supplements, and smoking habit. Overall, erythrocyte Mg levels remained stable over the course of pregnancy whereas a slight decline in plasma Mg was found (P < 0.08). Plasma Mg levels dropped significantly more among subjects who did not consume Mg-containing supplements compared with those who did (P < 0.03). Plasma Mg values were lower among subjects who were non-smokers vs. smokers and subjects with a GA of less than 4 years vs. a GA of 4 or more years (P < 0.05). Plasma and erythrocyte Mg tended to be lower among blacks than whites. In conclusion, Mg depletion was not evident among subjects who developed PIH by measurement of plasma or erythrocyte Mg, and these blood Mg values were not related to MAP overall. For the PIH group, MAP and plasma Mg were inversely related. Use of Mg-containing supplements may have attenuated a decline in plasma Mg over the course of pregnancy. GA and smoking habit may influence plasma Mg, and race may influence both erythrocyte and plasma Mg levels.

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