EARLY-PREG is an open-cohort clinical study with a preconception, longitudinal, bidirectional and counterfactual design. The aim of this cohort is to investigate the proteomic signatures of maternal-embryonic communication by interrogating a growing biorepository of maternal fluids and tissues collected during the first two weeks after fertilisation.
Participants in the EARLY-PREG cohort consist of healthy couples seeking pregnancy, as well as women who are not seeking to conceive. The three main outcomes in the cohort are defined according to menstrual cycles in which conception is achieved and those in which conception is not achieved. Their clinical definitions are as follows:
* Pregnancy with a full-term live birth refers to the cycle in which the ovum is fertilised, leading to pregnancy, with beta-hCG levels above the clinical threshold for a positive pregnancy test. * Early pregnancy loss refers to a miscarriage up to 12 6/7 weeks. * Non-pregnancy refers to a menstrual cycle in which conception does not occur, confirmed by a clinically negative beta-hCG test. When referring to the same individual, this is, by definition, considered the counterfactual to the corresponding conception cycle.
being between 18 and 40 years of age
not being pregnant
normal colposcopy
body mass index (BMI) between 18 and 29
pregnant women
history of alcoholism
infertility treatment
endometriosis
Women visiting gynaecologists, and midwives in private practices, public hospitals, and Family Health Centres (CESFAMs) in the Biobio region of Chile.
Cohort
Other
EMBRYO EXPOSURE
Other interventionThe counterfactual design of EARLY-PREG enables the comparison of the systemic and localised physiological effects associated with embryo appearance and implantation in an individual (the factual) against the physiological state of the same individual without experiencing pregnancy (the counterfactual).
Number of menstrual cycles leading to full-term pregnancies
This outcome refers to the menstrual cycle in which the ovum is fertilised, leading to pregnancy with a full term live birth. The conception cycle requires beta-hCG levels above the clinical threshold for a positive pregnancy test, which is determined in peripheral venous blood on the 14th day post-ovulation.
Number of menstrual cycles not leading to pregnancy
This outcome refers to a menstrual cycle in which pregnancy does not occur. When referring to the same individual, it is, by definition, considered the counterfactual to the conception cycle described above. A non-conception cycle is confirmed by a clinically negative beta-hCG test, which is determined in peripheral venous blood on the 14th day post-ovulation. This cycle is characterised by the absence of a clinical pregnancy.
Number of menstrual cycles leading to early pregnancy loss
This outcome refers to the menstrual cycle in which the ovum is fertilised, leading to a miscarriage until 12 6/7 weeks. The conception cycle requires beta-hCG levels above the clinical threshold for a positive pregnancy test, which is determined in peripheral venous blood on the 14th day post-ovulation.
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