Background Maternal thyroid hormone deficiency is the most common disorder of thyroid function during pregnancy and can influence the outcome for mother and foetus. The purpose of this study was to investigate the prevalence of thyroid hormone deficiency during the first half of pregnancy in iodine sufficient areas of China.

We summarize here our work to construct three-dimensional (3D) digital models of the human placental vascular network using data obtained from magnetic resonance imaging (MRI) of the placenta in vitro. Our preliminary findings indicate that these digital models provide a promising method with which to study placental vasculature. Correspondence to: Dr Z. J. Wang, Department of Obstetrics and Gynecology, NanFang Hospital, Southern Medical University, No.1838, North of Guangzhou Avenue, Guangzhou City, Guangdong Province, 510515 China (e-mail: wangzhijian2046@sina.com) In order to explore a method that images placental vessels in vitro by MRI and uses these data to construct 3D digital models of normal human placental vascular networks, we collected six full-term placentae and separated them into three groups. In the first group, perfusion fluid was mixed with the contrast agent Gd-DTPA (experimental Group 1), in the second group