Blood arsenic species linked to higher odds of pregnancy hypertension in Chinese cohort

A prospective birth cohort study in eastern Yunnan, China, has found that pregnant women with higher concentrations of arsenic in the As(V) form in whole blood had modestly higher odds of developing hypertensive disorders of pregnancy.

Women who went on to develop hypertensive disorders of pregnancy had higher whole-blood As(V) concentrations than those who did not, with geometric means of 2.10 versus 1.34 ng/mL and mean values of 3.96 versus 3.07 ng/mL, a difference that reached statistical significance. Each doubling of As(V) concentration was associated with a 24 percent increase in the odds of these disorders, with an adjusted odds ratio of 1.24 and a 95 percent confidence interval of 1.03 to 1.49. Women in the highest tertile of As(V) exposure had roughly three times the odds of the outcome compared with those in the lowest tertile, with an odds ratio of 3.04 and a confidence interval of 1.39 to 6.62, and the trend across tertiles was statistically significant. Restricted cubic spline analysis suggested an overall association, but found no significant evidence that the relationship departed from linearity.

The authors themselves urge caution about these findings. In their conclusion, they note that the association with As(V) was observed under limit-of-detection substitution approaches, but was not statistically significant in a detected-only analysis, which yielded an odds ratio of 1.17 with a confidence interval of 0.78 to 1.75 and a p-value of 0.462. They also state that residual confounding related to maternal body mass index cannot be excluded, and that the clinical relevance of the association requires cautious interpretation. The study was conducted in a setting of low-level environmental arsenic exposure, a context in which evidence on arsenic species during pregnancy has remained limited.

Beyond the blood-pressure findings, the study examined birth weight using Bayesian kernel machine regression to explore the joint associations of the arsenic species mixture. These analyses suggested species-specific and mixture-related associations with birth weight, with monomethylarsonic acid, known as MMA, showing relatively greater importance within the arsenic mixture. The researchers also applied unsupervised clustering to characterize arsenic metabolic patterns among the participants, and this exploratory analysis identified arsenic-speciation profiles that differed mainly in MMA concentrations and in methylation indices. The authors suggest that heterogeneity in arsenic methylation, particularly involving MMA and methylation indices, may contribute to differences in individual susceptibility.

The study team, led by Yang Xu, Tiantian Zhao and Heng Bai with senior author Huixin Wu, emphasizes that arsenic speciation and metabolism deserve attention when evaluating maternal and fetal health effects of arsenic exposure. The authors conclude that their findings warrant confirmation in larger prospective studies before any clinical implications can be drawn. As a prospective cohort of 437 women in one region of China, the study captures associations rather than proven causal effects, and its results on birth weight are described as exploratory. The work was published as an open-access article on 29 October 2026.

Subject of Research: Associations of maternal whole-blood arsenic species with hypertensive disorders of pregnancy and birth weight in a prospective birth cohort

Article Title: Association of whole-blood arsenic speciation with hypertensive disorders of pregnancy and birth weight: a prospective birth cohort study

Article References: Xu, Y., Zhao, T., Bai, H., Liu, L., Yan, T., Liu, H., Ma, Q. Y., You, D., Li, H., Bai, H., & Wu, H. (2026). Association of whole-blood arsenic speciation with hypertensive disorders of pregnancy and birth weight: a prospective birth cohort study. BMC Pregnancy and Childbirth. https://doi.org/10.1186/s12884-026-10146-9

Image Credits: AI Generated

DOI: 10.1186/s12884-026-10146-9

Keywords: arsenic, hypertensive disorders of pregnancy, birth weight, birth cohort, arsenic speciation, methylation, MMA, environmental exposure, pregnancy, epidemiology, Association, whole-blood