Plasmatic zinc concentrations during pregnancy in zinc-deficient rats in relation to neonatal outcome.

Zinc has long been known to be an essential element for the growth and development of living things. In fact, zinc is present or participates in a wide variety of metabolic processes including the metabolism of carbohydrates, lipids, proteins and polynucleotides. The purpose of our study was to determine some aspects of the involvement of zinc in intrauterine growth and development of the rat. Thirty female Wistar rats were assigned at random to 1 of 3 dietary treatments. Group A received a normal diet, group B received a zinc-deficient diet and group C received a zinc-deficient diet plus a supplement of zinc in the drinking water. Daily food consumption, weights and plasmatic zinc levels were measured on days 1, 10 and 20. Fetal weights on day 20 were also recorded. The results showed a significant difference in daily food consumption and weight gains of the dams between the group receiving the normal diet (group A) and the other two groups. Fetal weights showed a different pattern, there was a significant difference between the unsupplemented zinc-deficient group B and the other two groups which led us to think that the daily food consumption of groups B and C, even though enough to produce lower weight in the dams, was not sufficiently low to produce fetal malnutrition and that it was the adequate consumption of zinc which allowed the fetuses of group C to have similar weights to those in group A, emphasizing the requirement of this metal for normal growth.

Zinc concentration in amniotic fluid of zinc-deficient rats and its relation to fetal weight.

Zinc concentration in amniotic fluid and its relation to fetal weight were investigated in three groups of pregnant rats: group A received a zinc-adequate diet, and the rats of groups B and C were fed a zinc-deficient diet. Group C also received zinc supplementation in water. The daily food consumption, weight and plasma zinc levels on days 1, 10 and 20, zinc concentration in amniotic fluid, the number of implantation sites, the number of resorptions, the number of live fetuses and fetal weight were determined. Plasma zinc concentrations were significantly different at the end of gestation between group B (Zn = 167.6 +/- 26.6 micrograms/dl) and the other two groups (group A = 199 +/- 18.6 micrograms/dl; group C = 204 +/- 13.7 micrograms/dl). The number of resorptions was significantly higher in group B and the number of live fetuses was significantly lower in this same group (p less than 0.025). Fetal weight was significantly lower in group B (p less than 0.001). The zinc concentrations of the amniotic fluid were significantly lower in group B (14 +/- 4.7 micrograms/dl) as compared to group A (83 +/- 11.4 micrograms/dl) and C (82 +/- 21 micrograms/dl; p less than 0.001). There was a positive linear correlation between zinc concentrations in amniotic fluid and fetal weight, being r: 0.7379 (p less than 0.001).

Effect of zinc nutrition on parturition and postpartum in the rat.

The effects of zinc deficiency on parturition were studied in three groups of Wistar rats. Group A received a zinc-adequate control diet (Zn = 33 ppm), group B received a zinc-deficient diet (Zn = 2.6 ppm), and group C received the zinc-deficient diet plus a supplement of zinc in the drinking water (100 micrograms/ml). The results showed a prolonged parturition (p less than 0.05) in group B (149 +/- 42 min) as compared to group A (78.6 +/- 23.7 min) and group C (82.4 +/- 20.8 min). No significant difference was found in regard to uterine bleeding. A different pattern of maternal behavior was found in the animals of group B who did not retrieve or lactate the pups. The importance of an adequate zinc status for normal parturition is stressed.

Relation between maternal plasmatic zinc levels and uterine contractility.

336 pregnant women participated in a study to determine the possible relation between maternal plasmatic zinc levels ( PZL ) and uterine contractibility . PZL during gestation and at the moment of delivery were evaluated in relation to the mode of delivery, the duration of the active period of delivery, and the presence of hemorrhage during the first 30 min postpartum. A significant difference (p less than 0.001) between PZL at different periods of gestation was found. There were significant differences (p less than 0.05) between PZL and duration of the active period of delivery and PZL and final mode of delivery. In 10 cases, a cesarean section had to be performed due to uterine atony. In these patients, the PZL were significantly lower than in the rest. The role of zinc in uterine muscle contractibility is discussed. The possibility of supplementation in those women with low zinc levels (less than 60 micrograms/dl; 9 mumol/l) is recommended.