TOPLINE

Blood lead and mercury levels declined substantially among pregnant women in the UK compared with levels in the early 1990s, and methylmercury accounted for most mercury detected in the blood.

METHODOLOGY

• Researchers conducted a cross-sectional observational study within the PEAR Study to determine exposure levels of lead and mercury in pregnant women in the UK and compared findings with previous UK pregnancy cohorts, international data, and established levels of concern.
• They included 313 pregnant women aged 18 years or older who were at least 11 weeks of gestation between 2023 and 2024; 262 participants provided blood samples and 249 provided urine samples for analysis. Blood and urine samples were collected at a gestational age ranging from 8.3 to 15.9 weeks and from 8.6 to 17.5 weeks, respectively.
• Whole blood and urine samples were analysed using mass spectrometry to quantify levels of lead, mercury, and speciated mercury including methylmercury and inorganic mercury.
• All participants completed questionnaires capturing data on demographics, potential environmental and lifestyle sources of metal exposures, and detailed maternal dietary habits relevant to toxic metal exposures during pregnancy.

TAKEAWAY

• The mean blood level of lead was 5.8 μg/L, which was approximately 84% lower than that reported in ALSPAC in 1991-1992 and lower than that reported in subsequent UK pregnancy cohorts.
• The mean blood level of total mercury was 0.83 μg/L, which was approximately 60% lower than the level reported in ALSPAC in 1991-1992. Methylmercury accounted for 93% of total blood mercury and 77% of measured mercury species, suggesting that seafood remained the predominant source of mercury exposure.
• Urine levels of lead and total mercury showed a significant correlation with corresponding blood levels (P < .05).
• Fewer than 0.5% of blood lead values exceeded the UK level of concern of ≥ 50 μg/L and fewer than 1% exceeded the US level of concern of ≥ 35 μg/L, with results comparable to contemporary levels in other high-income countries in Europe and the US.

IN PRACTICE

"This study provides an impetus for the collection of data on exposures to toxic metals among women and other vulnerable populations in the UK, such as children, using larger samples and more representative populations," the authors wrote.

SOURCE

This study was led by Caroline M. Taylor, Centre for Academic Child Health, Bristol Medical School, University of Bristol, Bristol, England. It was published online on June 29, 2026, in BMJ Open.

LIMITATIONS

The findings may not be generalisable to other regions of the UK and populations with different demographic profiles. A high proportion of blood samples had inorganic mercury levels below the limit of quantification.

DISCLOSURES

This study received funding through a Medical Research Council Career Development Award. The authors declared having no competing interests.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.