Toxic metals, essential micronutrients, gestational thyroid hormones, and size at birth

• Main Author: Gustin Mossegård, Klara
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Institutet för miljömedicin / Institute of Environmental Medicine 2022
• Subjects: Sunderby Hospital; Northern Sweden
• Online Access: http://hdl.handle.net/10616/47973

The toxicity of the metals cadmium (Cd), lead (Pb), and methylmercury [MeHg; an organic and very toxic form of mercury (Hg)] in adults have long been recognized. It is also well-established that early-life exposure to Pb and MeHg is associated with neurodevelopmental toxicity. However, effects of commonly occurring low-level exposure from the diet on fetal growth has more recently gained some attention. Also, experimental studies have indicated that Cd, Pb, and MeHg may be endocrine disruptors that can interfere with thyroid function, which in pregnancy is critical for normal fetal development. Fetuses are particularly vulnerable to toxic insult, due to critical development in combination with undeveloped defense mechanisms. Effects on early development, such as impaired fetal growth, may adversely affect child health and have long-term health consequences later in life. Thus, a better understanding of the potential impact of commonly occurring dietary exposure to Cd, Pb, and MeHg on fetal development is of public health relevance. The overarching aim of this thesis was to clarify if and how dietary exposure to Cd, Pb, and MeHg in pregnancy may influence fetal growth. Specifically, this thesis aimed to elucidate whether maternal metal exposure during pregnancy affect infant birth size. We also assessed the potential influence of both toxic metals and essential micronutrients on maternal thyroid function in pregnancy, which is a critical hormonal system for normal fetal development. All studies within this thesis are based on data from an ongoing Swedish birth-cohort, called NICE (Nutritional impact on the Immunological maturation during Childhood in relation to the Environment), established in the catchment area of Sunderby hospital in northern Sweden. In total, 655 pregnancies are included in NICE. Recruited women (2015-2018) donated blood and urine in gestational week 27-36, which was used to assess the women’s exposure to metals during pregnancy. Erythrocyte concentrations of Cd, Pb, and total Hg (mainly ...