EUROP. J. OBSTET. GYNEC. REPROD. BIOL., 1979,9/2,75-80 o Elsevier/North-Holland Biomedical Press

Maternal and fetal plasma zinc in pre-eclampsia B.A. Bassiouni, A.I. Department

Foda and A.A.

of Obsterrics and Gynecology,

Faculty of Medicine,

Rafei

Faculty of Medicine, Mansoura University and the Department

of Biochemisrry,

Tanta University, Egypt

Accepted for publication 20 October 1978 BASSIOUNI, B.A., FODA, A.I. and RAFEI, A.A. (1979): Maternal and fetal plasma zinc in pre-eclampsia. Europ. J. Obstet. Gynec. reprod. Biol., 912, 75-80.

Zinc is important for fetal growth and is involved in several important enzyme systems. Maternal and umbilical plasma zinc concentrations were determined in 52 parturient women with mild and severe preeclampsia, and were compared with those obtained from 20 women in labor whose pregnancies had progressed normally. A decrease in maternal as well as umbilical plasma zinc concentrations was observed in preeclamptic women, and this decrease was statistically significant in severe pre-eclampsia. The causes of these changes in plasma zinc concentrations in pre-eclampsia were discussed, and the possible adverse effects of zinc deficiency on the mother and fetus were mentioned. Low plasma zinc concentrations in preeclampsia may be a sign of zinc deficiency, implying possible risks to the mother and her fetus. It is recommended that maintenance of adequate dietary zinc nutrition during pregnancy, and particularly in preeclampsia, is important. low plasma zinc concentrations; ---

normal pregnancy; mild pre-eclampsia; severe preeclampsia

Introduction

findings were observed in normal human pregnancy (Henkin et al., 1971; Bassiouni et al., 1974). Low plasma zinc levels were observed in renal disease with proteinuria (Sandstead et al., 1970) and in liver disease (Rosner and Gorfien, 1968; Halsted and Smith, 1970). This study is designed to clear up and define the behavior of maternal and fetal plasma zinc in preeclampsia in view of the associated renal and hepatic changes in the disease.

Zinc is a trace metal involved in cell and tissue growth (Williams and Chesters, 1970). Zinc plays an important role in nucleic acid (Hsu et al., 1969) and protein synthesis (Swenerton et al., 1969), and is intimately involved in several important enzyme systems (Underwood, 1971). Maternal plasma zinc concentration decreases during normal human pregnancy (Halsted et al., 1968; Rosner and Gorfien, 1968; Hahn et al., 1972; Bassiouni et al., 1974; Hambidge and Droegemueller, 1974; Jameson, 1976a and b). Lichti et al. (1970) noted a higher zinc level in the plasma of the fetus than the mother in sheep and goats, and similar

Material and methods

A group of 72 parturient women constituted the clinical material of our study carried out in Mansoura 75

B.A. Bassiouni et al.: Maternal and fetal plasma zinc in pre-eclampsia

76

University groups:

Hospital.

They were classified

into

two

amount of heparin, centrifuged, and the separated plasma was put in glass-stoppered tubes and kept at -20°C until processing within 6 h. Plasma zinc levels were estimated by atomicabsorption spectrophotometry, using a Pye-Unicum S.P. 90A Series 2 atomic-absorption spectrophotometer, after digestion with trichloroacetic acid, t&ing precautions to avoid contamination (Hambidge and Droegemueller, 1974). The method used is that described by Rosner and Gorfien (1968). All samples were run in duplicate. Controls were made against standard sera and standard dilutions. The intra- and inter-assay coefficients of variation were 1.19 and 1.43%, respectively. Differences in mean concentrations of maternal versus maternal, cord versus cord and maternal versus cord plasma were analyzed by the Student’s r-test. P values of 0.05 or less were considered significant (Snedecor, 1956). Venous blood was obtained from 12 apparently healthy postmenstrual non-pregnant women. All were of child-bearing age, and none were receiving drugs or contraceptive steroids. The mean plasma zinc levels of these women represent the non-pregnant zinc level in our community.

Group

I; 52 pre-eclamptic women admitted for confinement to the Obstetric Section during the years 1976 and 1977 (28 with mild pre-eclampsia and the rest with a severe degree). The international standards for classification of preeclampsia proposed at the Paris Meeting of the Gestosis Organization held in 1970 were adopted. Group II: 20 parturient normal pregnant women of the same range of age, parity and more or less of the same socio-economic standard, serving as a control group (Table I). A complete general medical and obstetric examination was done for all cases. Special attention was paid in selecting our cases to exclude recent or current infections, nutritional and parasitic diseases. None were receiving any medication. Seven of the normal group were primiparae, while in mild and severe pre-eclampsia the numbers of primiparae were 9 and 8, respectively. All deliveries were uncomplicated, vaginal and at term. All were delivered of a single live infant free from congenital malformations and with a birth weight between the 10th and 90th centiles of the normal distribution, within 38 and 42 wk of the last menstrual cycle, after correction for sex of baby, parity, maternal height and weight (Table I). At delivery, venous blood was aspirated from the antecubital vein of the mother, and cord blood samples were obtained by collecting the blood between two clamps immediately after delivery. Blood samples were immediately placed into acidrinsed centrifuge glass tubes containing a fixed

TABLE I

Clinical details and birth-outcome No. of

Results The maternal plasma zinc of normal pregnant women during parturition shows a significant decrease when compared with non-pregnant women (P < 0.001) (Table II). Comparing patients with severe pre-eclampsia with

of patients studied Parity

Age (Y1)

cases Mean * SD

Median

Range

Mean f SD

Gestation period (wk)

Fetal birth weight (kg)

Mean r SD

Mean r SD

Range

Normal pregnancy

20

26 f 5.57

25.5

17-39

3.0 f 1.6

l-5

40.1 * 0.91

3.48 i 0.4

Mild preecIampsia

28

27 t 5.51

26.5

18-38

2.8 r 1.3

l-4

40

+ 1.10

3.47 + 0.7

Severe preeclampsia

24

26 f. 4.52

25.5

17-38

3.2 f 1.8

l-5

39.8 + 0.97

3.46 + 0.6

B.A. Bassiouni et al. : Maternal and fetal plasma zinc in pre-eclampsia

TABLE II

Non-pregnant plasma zinc compared with the maternal plasma zinc in normal pregnant women during parturition No. of cases

Non-pregnant Normal pregnant

TABLE III

12 20

Plasma zinc (@g/100 ml) Mean

Range

SD

100.08 64.60

78--118 38-98

+ 8.37 * 11.37

Normal pregnancy Mild pre-eclampsia Severe pre-eclampsia

< 0.001

20 28 24

Plasma zinc &g/l00 ml) Mean

Range

SD

64.60 60.42 41.08

38-98 35-90 22-65

+ 17.31 k 16.27 + 11.65

normal pregnant women, there is a statistically significant fall in maternal plasma zinc levels (P< O.OOl), but no significant decrease is observed in mild preeclampsia when compared with normal pregnant women (P > 0.5) (Table III). However, comparison of the two groups of pre-eclamptic patients shows a significant decrease in the maternal plasma zinc in severe degrees of the disease (P < 0.01). A fall in the umbilical cord plasma zinc is noted in

P values

>0.5 CO.001

mild and severe pre-eclampsia when compared with normal pregnancy; this decrease is statistically insignificant in mild (P> 0.1) and significant in severe degrees of the disease (P< 0.001) (Table IV). A significant fall in umbilical plasma zinc is observed in severe preeclampsia when compared with mild preeclampsia (P< 0.01). A statistically significant rise in plasma zinc levels is noted in the umbilical cord plasma when compared

Umbilical plasma zinc in normal pregnancy, mild and severe pre-eclampsia No.of cases

Normal pregnancy Mild pre-eclampsia Severe pre-eclampsia

TABLE V

P value

Maternal plasma zinc in normal pregnancy, mild and severe pre-eclampsia at labor No.of cases

TABLE IV

77

20 28 24

Plasma zinc (fig/ 100 ml) Mean

Range

SD

P values

84.75 78.48 53.85

60-l 10 56-102 34-90

f 15.36 c 21.29 * 18.53

>o.i