Date Published: February 7, 2019
Publisher: Public Library of Science
Author(s): Jejelola I. Ladele, Iretiola Bamikeolu Fajolu, Veronica Chinyere Ezeaka, Pal Bela Szecsi.
Lead toxicity is a cause of intellectual disability in children and majority of affected children live in developing countries. Its adverse effect on pregnancy outcome has also been documented.
To assess the relationship between maternal blood lead levels and umbilical cord blood lead levels in their corresponding newborn infants; to determine factors associated with high blood lead levels and the pregnancy outcome in participants.
This was a cross-sectional descriptive study carried out at a tertiary Teaching Hospital, Lagos, Nigeria. Four hundred and forty pregnant women and their respective newborns delivered at the study centre. Blood samples were obtained from the mothers and umbilical cord of the newborns at delivery and analysed by atomic absorption spectrophotometry. Socio-demographic and obstetric data was obtained by questionnaires administered to the mothers. The anthropometric measurements of the babies were taken at birth and clinical data recorded. Main outcome measures were blood lead levels in mother and baby pair, socio-demographic factors, birth weight, gestational age, length, occipito-frontal circumference.
The median maternal and umbilical blood lead level was 64.3μg/dl and 39.2μg/dl respectively. The levels were above 5μg/dl in 75.6% and 66.8% of mothers and umbilical cord respectively. There was a strong positive correlation between the maternal and umbilical cord blood lead levels (rs = 0.80). Use of calcium supplements during pregnancy was significantly associated with a lower maternal blood lead level (p = 0.010) while recent painting and renovation of residential accommodation were associated with a higher umbilical cord blood lead level (p = 0.025). There were no statistically significant associations between the maternal and umbilical cord blood lead levels and the gestational age and anthropometry of the newborns at birth.
The blood lead levels in newborns of women residing in Lagos, Nigeria are high and administration of antenatal calcium is associated with lower blood lead levels.
Lead is a recognized toxic agent in humans and the effects of its exposure and toxicity are well documented.[1–3] Lead has no known health benefit; rather it has been shown to have adverse effects on several body systems. [4,5] Children, including newborns, are particularly more vulnerable to the adverse effects of lead because of their developing brain. [2,3] Despite several attempts by many countries globally to reduce lead contamination of the environment, lead exposure and toxicity still remains a global public health problem.  According to the World Health Organization, lead toxicity contributes to 600,000 new cases of intellectual disabilities every year in children6 and 99% of children affected by lead toxicity live in the developing world.
Four hundred of 440 mother-newborn pairs recruited for the study had complete maternal-cord blood samples and questionnaires and were included in the analysis. Table 1 shows a summary of the socio-demographic characteristics of the mothers.
The median blood lead level obtained for the mothers was 63.7μg/dl (range of 0–332μg/dl) and this is similar to the value reported in another study in Lagos. This value is 12 times higher than the current intervention cut off value of 5μg/dl. This finding may likely be due to the higher levels of lead contamination in Lagos environment as published by several authors[7,21,58,59,60,61] which invariably translates to a high exposure level to the inhabitants. Several factors such as emissions from vehicles, tricycles, motorcycles, generating sets and industrial emissions, widespread construction and use of lead based paints account for the higher lead contamination. The possible implication of this is that there is a high risk of severe health effects of lead on pregnant women and their off-springs in Lagos.
Study highlighted the prevalence of elevated maternal and cord blood lead levels and adds to the existing body of evidence of high blood lead levels in Nigerians. There is therefore an urgent need to draft and enforce regulations on the manufacture, import, export, sale and distribution of lead containing products like paint and fuel in addition to educating the public on the hazardous effects of lead to control this problem.