The aim of this study is to understand the epigenetic and transcriptomic mechanisms that regulate the fetal origin of adult diseases (FOAD), either for the presence of metabolic disorders in the future mothers, such as obesity or for the exposure to certain contaminants such as tobacco.

To do that, the miRNAs profiles secreted to the endometrial fluid in obese women vs normoweight women during the window of implantation will be identified. Likewise, it will be studied how that miRNA signature is normalized once a substantial loss of weight is produced by the patients involved in the studied. In parallel, a comparison of the miRNA expression profiles secreted in the endometrial fluid in smoker women vs nonsmoker women will be performed. As in the previous case, it will be studied if after the exposure to these contaminant, the normalization of the miRNA expression signature occurs. Finally, an in silico analysis will be carried out in order to define the target genes and the metabolic pathways affected by the miRNAs profile secreted in both pathological conditions

The developmental origins of adult disease are now recognized to be related to intrauterine conditions during embryonic and fetal life. Pregnancy begins with embryo implantation and its impact in adult life remains unknown. It has been demonstrated that human endometrial epithelium secretes specific microRNAs (miRNAs) during the time frame when the embryo enters the uterine cavity and initiates its adhesion to the uterine wall. Maternal miRNAs are secreted to the endometrial fluid, transported through exosomes or bound to proteins and consequently uptaken by the preimplantation embryo, before implantation occurs. As a consequence they suffer transcriptomic modifications that induce profound molecular and functional changes. The data already published demonstrate a novel paradigm: the transcriptomic maternal endometrial regulation of the pre-implantation embryo in health.

Here, this novel maternal endometrium-based mechanism will be applied in order to understand and prevent the developmental origin of adult diseases induced during embryonic implantation either by metabolic disorders of future mothers who have developed obesity or by the exposure to certain contaminants such as tobacco. In this project, the expression profiles of secreted miRNAs will be identified in the endometrial fluid in obese women compared to normo-weight women. Also, it will be studied how this "obese" endometrial miRNA pattern is reversed after weight-loss. In parallel, murine models of obesity will be used to proof this concept. In addition, the expression profiles of secreted endometrial miRNAs will be identified in smokers versus future non-smokers mothers. As in the previous case, the reversion of this signature will be analysed after stopping the exposure to this contaminant.

Then, "in silico" analysis will be done to select putative genes and functional pathways targeted by the signature of secreted endometrial miRNAs in the human and murine models in both pathological conditions. The determination of the transcriptomic and/or epigenome modifications induced by "obese" or/and "smoker" endometrial miRNAs in preimplantation mouse embryos is expected. As preliminary results, to support this project our accepted model of transcriptomic maternal endometrial regulation of the pre-implantation embryo in health, and the identification of a differential pattern of secreted miRNAs in the endometrial fluid of obese women compared to normo-weight counterparts is presented. In consequence, the application of this novel endometrium-based mechanism to the understanding and prevention of the origin of adult diseases related to obesity and/or tobacco exposure is proposed.

Inclusion Criteria:

• Women with age comprised between 18 and 45 years
• Normal uterus (evaluated trough ultrasound 2D/3D and/or hysteroscopy)
• Presence of at least one ovary
• Body mass index:
• Normoweight: 18.0-24.9 kg/m2 and non smokers
• Obese ≥30.0 kg/m2 and non smokers
• Smokers: Normoweight and smoke at least 10 cigarettes per day

Exclusion Criteria:

• Overweight=25.0-29.9 kg/m2
• Patients with Intrauterine device in the last 3 months
• Patients who had had hormonal contraceptives in the 2 previous months.
• Adnexal or uterine pathologies
• Polycystic ovary
• Existence of serious or uncontrolled bacterial, fungal or viral infections that could interfere with the involvement of the patient in the study or in the evaluation of the study results.
• Any disease or medical condition that could be unstable or could endanger the security of the patient and her compliance in the study.

Endometrial fluids from non-smoker obese and normoweight samples will be analysed in the window of implantation. In turn, endometrial fluids from normoweight smoker and non-smoker patients will be analysed in the window of implantation.

These participants will be recruited in just one centre: IVI Valencia. Their recruitment will be done through a routine consultation carried out by the research team from the centre, as well as through the revision and daily evaluation of the medical reports and subsequent contact with those patients who could accomplish with the criteria selection and desire to be involved in the study.