Study protocol: The cross-sectional Uppsala weight gain in pregnancy study (VIGA study)

Background: More than two in five Swedish women are overweight or obese when becoming pregnant. Maternal overweight or obesity and excessive pregnancy weight gain are associated with several adverse pregnancy outcomes. The underlying mechanisms that link maternal adiposity, diet, exercise, pregnancy weight gain with pregnancy outcome are incompletely understood. Methods: We describe the design for a cross-sectional study of pregnant women at Uppsala University Hospital, Sweden. All participants delivered by elective cesarean section before the onset of labor. At inclusion, participants answered two questionnaires concerning their dietary and exercise habits. Fasting maternal blood samples (buffy coat, plasma, serum) were collected. During the cesarean section, biopsies of maternal subcutaneous and visceral adipose tissues were obtained. Placental tissue was collected after delivery. All biological samples were processed as soon as possible, frozen on dry ice, and stored at -70 degrees C. Pregnancy outcomes and supplementary maternal characteristics were collected from medical records. Results: In total, 143 women were included in the study. Of these women, 33.6% were primiparous, 46.2% had a pre-pregnancy body mass index (BMI) over 25 kg/m(2), and 11.2% of the offspring were born large for gestational age (LGA). Complete collection, that is both questionnaires and all types of biological samples, was obtained from 81.1% of the participants. Conclusions: This study is expected to provide a resource for exploration of the associations between maternal weight, diet, exercise, pregnancy weight gain, and pregnancy outcome. Results from this study will be published in peer-reviewed, international scientific journals. This study was approved by the Regional Ethics Review Board in Uppsala (approval no 2014/353) and with an amendment by the Swedish Ethical Review Authority (approval no 2020-05844).