Related Experiment Video
Updated: Aug 11, 2026

Generation of the Early-Gestational Maternal Immune Activation Mouse Model to Assess Prenatal Inflammation on Neurodevelopment
Published on: March 24, 2026
Maternal lead exposure and the secondary sex ratio
John F Jarrell1, Marc G Weisskopf, Jennifer Weuve
1Harvard School of Public Health, Harvard University, Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Boston, MA, USA. john.jarrell@calgaryhealthregion.ca
Background:
A reduction in the secondary sex ratio may be associated with exposure to environmental toxicants. Little data exists relating this outcome to lead exposure, a well-known reproductive toxicant.
Methods:
We studied 1980 women having singleton births from 1994 to 1995 and from 1997 to 2001 who participated in a cohort study of lead exposure and infant outcomes in Mexico City. Levels of lead were measured in maternal and cord blood using graphite furnace atomic absorption spectroscopy, and levels of lead in maternal patella and tibia bone (a reflection of cumulative exposure) were measured using noninvasive K-X-ray fluorescence measurements. Using logistic regression models, we evaluated the relations of these measures to secondary sex ratio in the offspring, adjusting for maternal age, parity and year of infants' birth.
Results:
We found no consistent association between any of the lead measures and secondary sex ratio. Results were unchanged when we adjusted for infants' year of birth, maternal age and parity.
Conclusions:
Despite a large sample size and the use of sensitive biomarkers, we did not find evidence that maternal and fetal lead exposure is associated with a lower secondary sex ratio among newborns.
Related Concept Videos
The Ratio of X Chromosome to Autosomes
Normal male Drosophila has a ratio of one X chromosome to two sets of autosomes. In contrast, normal female Drosophila...
Sex Linked Disorders
Sex-linked Disorders
Teratogenicity
Meiosis vs. Mitosis
Before the start of mitosis and meiosis I, the cell synthesizes DNA, resulting in two homologous copies of each chromosome. DNA synthesis is...
Dosage Compensation
In addition to sexual development, the X chromosome has genes involved in autosomal functions such as brain development and the immune system. Therefore, males and females with distinct numbers of X chromosomes will have...
