The endocrine disruptors among the environmental risk factors for stillbirth.

Persistent organic pollutants have been lately taken into consideration for their adverse effects, as possible stillbirth contributors; stillbirth can be in fact considered the most dramatic pregnancy complication. Congenital abnormalities account for few stillbirths and many related disorders are potentially modifiable or often coexist, such as maternal infections, non-communicable diseases, lifestyle factors and maternal age. Causal pathways for stillbirth frequently involve impaired placental function, either with fetal growth restriction or preterm labour. For this reason, many current efforts are focusing on the study of endocrine disruptor (ED) placental transfer, to better understand the in utero exposure dynamics. In this regard, our research group has investigated, by gas chromatography-mass spectrometry, the EDs presence in brain samples of 24 stillbirths, collected over a 3-year period (2012-2014), coming from the Northeast Italy, a notorious area devoted to apple cultivation. Surprisingly, organochlorine pesticides (OCPs), well-known EDs, have been detected in 11 samples. Apart from the noteworthy evidence of pesticides' bio-persistence, this finding implies a redefinition of the placental barrier concept: not a real safety system, but a time-deferral mechanism of absorption. The term 'placental barrier' in fact refers to a 4-membrane structure, made up by two epithelial layers, which exactly lining the chorionic villi, and by two endothelial layers, belonging to the feeding vessels for the fetus. It is an effective barrier only for a low administration of water-soluble substances, which encounter obstacle to cross four instead of two membranes. High doses of water-soluble compounds can reach appreciable concentration in the fetal blood, and the lipid-soluble chemicals, such as EDs, are able to pass the placental barrier, through a simple mechanism of passive diffusion, even in minimal concentrations. After crossing the placental barrier, it is emerged from our results that they can also pass through the still immature blood-brain barrier of the fetus.