Abstract:
BACKGROUND
The impact of prenatal exposure to cadmium (Cd) on birth outcomes is an area of concern.
This study aimed to assess an impact of prenatal Cd exposure on birth outcomes in distinct
coastal populations of South Africa.
METHODS
Cadmium was measured in maternal blood (CdB) (n = 641), cord blood and in maternal
urine (n = 317). This investigation assessed the associations between CdB (non-transformed)
and birth outcomes across the 25th, 50th, and 75th percentile for birth weight, birth
length and head circumference, to test for a linear trend. Associations between natural
log-transformed maternal CdB, size at birth and other factors were further evaluated using
linear mixed-effects modelling with random intercepts.
RESULTS
The average gestational age in the total sample was 38 weeks; 47% of neonates were
female, average birth weight was 3065 g and 11% were of low birth weight (< 2500 g). The
geometric mean (GM) of the maternal CdB level was 0.25 μg/L (n = 641; 95% CI, 0.23– 0.27). The cord blood Cd level was 0.27 μg/L (n = 317; 95% CI, 0.26–0.29) and urine (creatinine-
corrected) Cd level was 0.27 μg/L (n = 318; 95% CI, 0.24–0.29). The CdB cord:maternal
ratio in the sub-cohort was 1, suggesting that the placenta offers no protective
mechanism to the foetus. An inverse association was found between CdB and the lower
birth weight percentile in female neonates only (β = - 0.13, p = 0.047). Mothers who reported
eating vine vegetables daily had lower levels of CdB (β = - 0.55, p = 0.025). Maternal smoking
was associated with an elevation in natural log-transformed CdB levels in both male and
female cohorts.
DISCUSSION
Significant inverse associations between prenatal Cd exposure and birth anthropometry
were found in female neonates but not in male neonates, suggesting potential sex differences
in the toxico-kinetics and toxico-dynamics of Cd.
