Genetics of Glucose Regulation in Gestation and Growth (Gen3G) Cohort - Placenta Transcriptomics RNA Sequencing

The overarching goals of Genetics of Glucose regulation in Gestation and Growth (Gen3G) are to increase our understanding of biological, environmental, and genetic determinants of glucose regulation during pregnancy and their impact on fetal/child development. Gen3G is a prospective cohort study: we initially recruited 1,024 pregnant women between 2010-2013 at Blood Sampling in Pregnancy Clinic during the first trimester of pregnancy (median 9 weeks of gestation) in Sherbrooke, Québec, Canada. We assessed 898 pregnant women at second trimester (median 26 weeks of gestation), when participants completed a 75g oral glucose tolerance test (OGTT) as clinically indicated for screening of gestational diabetes mellitus (GDM). We collected data for 854 mother-child dyads at delivery (from medical records), in addition to placenta and/or cord blood samples in majority of newborns.The overall goal of the grant that supported data that is included in this dbGaP submission was to discover novel placental factors that regulate glucose metabolism in pregnancy and predict GDM by conducting genome-wide transcriptomics (RNA and miRNA) in carefully collected placenta samples from Gen3G.]]>
Inclusion criteria: Age ≥ 18 yrs; gestational age ≤16 weeks from last menstrual period Exclusion criteria: known pre-pregnancy diabetes, taking medications interfering with glucose metabolism; first trimester A1c ≥6.5% (criteria for existing diabetes status), alcohol consumption >2 drinks/day; involved in regular high intensity physical activity; non-singleton pregnancy ]]>
Visit 1 (2010-2013): first trimester (≤ 16 weeks of gestation). We collected data on maternal age, gravidity, parity, lifestyle questionnaires (smoking, alcohol consumption, diet [limited food items], and leisure physical activities), medical history and anthropometrics and vital signs measurements (according to standardized research protocols). An extra blood sample was collected (for the majority of participants, 1h post 50g glucose challenge test). Visit 2 (2010-2013): second trimester between 24 and 30 weeks of gestation, concomitantly with clinically indicated GDM screening test (fasting 75g oral glucose tolerance test [OGTT] over 2-hour). Participants completed similar lifestyle questionnaires to the first trimester visit. Research staff updated medical history and measured anthropometrics and vital signs (according to standardized research protocols). We collected extra blood samples at each point (0, 60 and 120 minutes) of the OGTT. Visit 3 (2010-2014): delivery. Research staff extracted clinical data from electronic medical record of participants and their child, including birth weight and birth length (measured by clinical staff). For a subgroup of children, research staff measured newborns skinfolds thickness measurements, according to standardized research protocols. Research staff also collected biological samples (cord blood and placenta) within 30 minutes after delivery. Biological samples were rapidly processed and stored in RNAlater at -4C for ~24h before to be stored at -80C until DNA/RNA extraction. ]]>