Smoking during pregnancy and the perinatal cadmium burden

Abstract

The association between maternal smoking and both morphometric birth parameters and the perinatal cadmium burden were studied. The cadmium concentrations were measured by atomic absorption spectrometry in 100 samples of maternal whole blood (MB) and in 93 samples of umbilical cord blood (CB). In the group of nonsmokers, significantly higher birth weight and decreased relative placental weight were noted as compared to the group of smokers who smoked more than 6 cigarettes a day (p less than 0.05). In both maternal and cord blood samples, the measured Cd levels were found to be significantly higher in smokers than in the nonsmoking subjects (for MB and CB p less than 0.01 and p less than 0.01 respectively). The average number of cigarettes smoked daily by the women had little effect on the levels of the metal. The Cd-MB strongly correlated with the Cd-CB (p less than 0.001). The cadmium values determined in MB and CB did not significantly affect any of the studied fetoplacental parameters. The reported findings give support for placental permeability to cadmium in humans and confirm that smoking during pregnancy leads to elevated Cd concentrations in both the mother and the fetus.

PIP: 100 healthy parturients and 100 neonates born to them between 37-42 weeks of pregnancy in the Institute of Obstetrics and Gynecology in Lublin, Poland, participated in an investigation designed to demonstrate whether smoking during pregnancy alters the perinatal cadmium burden and, if so, what influence this may have on morphometric fetoplacental parameters. 37 women did not smoke during pregnancy; the remaining 63 were current smokers. The median value of the number of cigarettes smoked daily was 6. The smoking group was divided into 2 subgroups: smokers who smoked 6 or less cigarettes per day and those who smoked more than 6 cigarettes per day. None of the differences calculated for mean age, parity, and the duration of pregnancy between the subgroups of women studied was statistically significant. The mean birth weight of the neonates born to nonsmoking mothers was significantly higher than that of the group smoking less than 6 cigarettes per day. The mean placental weight in the nonsmokers was higher than in both subgroups of smokers, but these differences were insignificant. When relative placental weight was evaluated, the difference between the group smoking more than 6 cigarettes per day and the nonsmokers appeared to be statistically significant. A slight insignificant decrease in Roher's ponderal index was observed in the newborns of smoking mothers as compared to the infants of nonsmokers. Detectable cord (Cd) concentrations were found in 27.0% of the blood samples obtained from nonsmoking mothers and in 32.4% of umbilical cord blood (CB) samples obtained from their neonates while in the smoking group detectable maternal blood (MB) and CB cadmium levels were measured in 61.9% and 57.1% of samples respectively. These differences were statistically significant. The average number of cigarettes smoked per day by the women had little effect on the measured metal levels. There was a markedly significant correlation between MB and CB cadmium levels. In 19.4% of cases, Cd-CB exceeded the corresponding MB value. The direction of the transplacental gradient for cadmium as estimated by the sign test was statistically insignificant. None of the fetoplacental parameters studied was significant associated with cadmium levels in MB and CB. The study results confirm that the physical development of newborns with fetal tobacco syndrome is retarded in comparison to the neonates of nonsmoking mothers.