International Journal of Gynecology & Obstetrics 55 (1996) 175-176

Brief communication

Zinc levels in pregnancy

S.S. George*a, S. Swaminathanb, L. Seshadri”

aDepartment of Obstetrics and Gynecology, Christian Medical College Hospital, Vellore, India ‘Department of Clinical Biochemistry, Christian Medical College Hospital, Vellore, India

Received 18 March 1996; revised 3 July 1996; accepted 8 July 1996

Keywords: Plasma zinc; Erythrocyte zinc; Leukocyte zinc

Zinc levels in plasma, leukocyte and erythrocyte in normal pregnancies have been studied by various authors [ 1,2]. The results have been con- flicting, plasma and leukocyte zinc levels showing a decrease and erythrocyte levels showing an increase. The only Indian study on pregnant women has revealed low serum zinc levels in I and II trimesters [3]. We therefore undertook a pros- pective study to assess zinc levels in pregnancy in South Indian women.

Fourteen healthy antenatal patients who did not have systemic infections, cardiac or renal disease and who were on oral iron supplements were studied. Zinc levels in plasma, erythrocyte and leu- kocyte were measured in I, II and III trimesters in all of them. Twenty-five non-pregnant patients of the reproductive age group were selected as con- trols and zinc measurements were carried out. Zinc determinations in plasma, erythrocytes and leuko- cytes were done using a Perkin Elmer atomic ab-

l Corresponding author. Tel.: 91 416 22102; fax: 91 416 32103, 91 416 32035.

sorption spectrophotometer and expressed as &lo0 ml, kg/g Hb and ng/mg dry weight, respec- tively. The statistical analysis was performed using Student’s r-test and Pearson correlation co- efficient.

Analysis of the results revealed that the plasma zinc levels were significantly lower in pregnant women during the 3 trimesters compared to the non-pregnant controls (Table 1). The levels in II and III trimesters were significantly lower than in I trimester. Most studies by other authors have revealed the same observation. This decrease in plasma zinc levels in pregnancy is the effect of hemodilution and low albumin levels.

However the erythrocyte and leukocyte zinc lev- els were similar in pregnant women in all 3 trimesters and non-pregnant women, indicating that there is no zinc deficiency in normal pregnancy.

There was no significant correlation between plasma zinc levels and erythrocyte or leukocyte zinc in the pregnant and non-pregnant women. But there was a significant positive correlation be-

0020-7292/96/%15.00 0 1996 International Federation of Gynecology and Obstetrics PII SOO20-7292(96)0275 I-8

176 S.S. George CI al. / Inrerna~ionnl Journal of Gynecology & Obsrerrics 55 (19%) 175- I76

Table I

Zinc levels in pregnant and non-pregnant women

Zn indices

Mean f SE.

Non-pregnant

n = 25

Pregnant n = 14

Trimester I Trimester II Trimester III

Plasma pgilO0 ml 91.3 f 1.7 SO.36 f 4.2 67.71 f 2.3 69.19 f 2.9 RBC Hb rg/g 46.8 f 0.4 45.28 f 1.8 44.51 f 2 48.21 f 2.4

WBC ngmg (dry weight) 60.4 f 0.5 60.86 f 2.6 56.71 f 2.7 57.93 f 2.9

Correlation coefficient

Plasma, RBC

Plasma, WBC RBC, WBC

0.25 0.2 0.36 0.08

0.28 0.28 0.45 0.18 0.58"' 0.59' 0.57* 0.17

***f < 0.001; 'P < 0.056.

tween erythrocyte and leukocyte zinc in the non- pregnant state and during pregnancy except in the third trimester. This indicates that plasma zinc is not a reliable index of zinc status in pregnancy. Erythrocyte and leukocyte measurements give a fair assessment of the zinc status and preferably both of these indices should be measured. Erythrocyte zinc measurement is technically simpler, less time consuming and less expensive and has the least variation among the three in- dices. Therefore, erythrocyte zinc appears to be a reliable and cost effective index of maternal zinc status.

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