Postnatal Growth Following Prenatal Lead Exposure and Calcium Intake

Abstract

WHAT'S KNOWN ON THIS SUBJECT:Lead is an ubiquitous environmental pollutant, and no safe threshold for blood lead level in children has been discovered yet. Prenatal lead exposure affects growth of children.WHAT THIS STUDY ADDS: Low level of prenatal lead exposure of ,5.0 mg/dL affects postnatal children' s growth, which was further intensified by low calcium intake. abstract BACKGROUND: The effects on postnatal growth of maternal exposure to low levels of lead during pregnancy have not been well established. In addition, information is limited regarding the protective effect of dietary calcium intake during pregnancy against the effect of lead for fetal and postnatal growth. We investigated the relationship between prenatal exposure to lead and growth at birth and 6, 12, and 24 months postnatal, and evaluated the role of calcium intake against the effect of lead. METHODS:A total of 1150 pregnant women, and their subsequent offspring, enrolled in a prospective birth cohort study (Mothers and Children' s Environmental Health Study), were evaluated. Multivariable regression analysis was conducted to estimate the effects of prenatal maternal blood lead levels on growth at each follow-up. RESULTS:The blood lead levels of participating mothers were ,5.0 mg/dL and mean levels were 1.25 mg/dL during the early (before 20 gestational weeks) and late (at delivery) gestational periods. Prenatal exposure to lead, particularly in late pregnancy, was significantly associated with a reduction in infantile growth at 24 months. When pregnant women had dietary calcium intake at mean or upper level, the association was not significant. In contrast, lower than mean level of calcium intake intensified the adverse effect of prenatal lead exposure on growth in children.CONCLUSIONS: Prenatal lead exposure ,5.0 mg/dL adversely affects postnatal growth and low calcium intake aggravates the effect, indicating more stringent control of lead and sufficient intake of calcium are necessary to help children' s health.

The association of lead exposure during pregnancy and childhood anthropometry in the Mexican PROGRESS cohort

“…There are many ways by which lead could directly or indirectly affect bone cell function and then alter children’s height and body composition (Pounds et al 1991). There were some previous studies that performed an analysis similar to ours (Afeiche et al 2011; Hong et al 2014; Schell et al 2009). They performed a prospective analysis looking at lead exposure during pregnancy related to children’s growth.…”

“…In particular, previous investigations identified significant negative correlations between blood lead (BlPb) levels during childhood and child stature and growth over time (Schwartz et al 1986 (United States; blood; range 5 to 35 μg/dL); Vivoli et al 1993 (Italy; blood; mean 7.8 μg/dL); Kafourou et al 1997 (Greece; blood; mean 12.3 μg/dL, sd 8.9); Ballew et al 1999 (United States; blood; mean 3.6 μg/dL); Frisancho and Ryan 1991 (United States; blood; mean 0.5 μmol/L); Cantoral et al 2015 (Mexico; blood; median 0.17 μmol/L); Dallaire et al 2014 (Canada; blood; mean 2.7 μg/dL sd 2.1)). Other studies observed negative associations between lead exposure during pregnancy and children’s height and weight (Schell et al 2009 (New York; blood; mean 2.8 μg/dL, sd 2.63); Afeiche et al 2011 (Mexico; tibia, patella; mean 8.7 μg/g, 10.4 μg/g, sd 9.7, 11.8); Hong et al 2014 (South Korea; blood; mean 1.25 μg/dL sd 1.5)). However, most previous studies focused on postnatal exposures and did not measure exposure to lead during pregnancy.…”

Detectable Blood Lead Level and Body Size in Early Childhood

“…Afeiche et al (2011) demonstrated that prenatal lead exposure, measured as maternal bone lead, was associated with decreased weight at age 5 years, but only among female children [25]. Prenatal lead exposure, measured in maternal blood, was associated with reduced weight and length Z-scores in offspring at age 2 years participating in the Mothers and Children’s Environmental Health Study [26]. Our findings were restricted to those based on BMI, which may suggest that early life exposure to lead is associated with a weight disproportionate to height, rather than to weight or height alone.…”

Is Prenatal Lead Exposure a Concern in Infancy? What Is the Evidence?

“…21 The samples of infant-mother dyads were from a myriad of countries including Brazil, 40 Mexico, 16 Iran, 20 , 29 Saudi Arabia, 36 , 39 India, 21 , 30 Tanzania, 31 Poland, 17 Spain, 32 Kuwait, 33 Belgium, 34 China, 19 Argentina, 35 South Korea, 37 and South Eastern Nigeria. 38 Five of the studies 16,17,29,36,37 utilized longitudinal designs to evaluate infant anthropometric growth or developmental outcomes in relationship to maternal lead levels changes throughout pregnancy or to examine cognitive outcomes in infants exposure to Pb 2 + based on umbilical cord blood level samples. For context, when much of the data were collected, the Centers for Disease Control and Prevention (CDC) recommendation was Pb 2 + level 10 μ g/dL or less; however, a Pb 2 + level of 5 μ g/dL or more is considered a level 418 Allen of concern.…”