Representativeness of Participants in a Lifestyle Intervention Study in Obese Pregnant Women - the Difference between Study Participants and Non-Participants

OBJECTIVE To examine the representativeness of participants attending a lifestyle intervention study addressing obese pregnant women. METHODS Retrospective comparison of baseline data, attendance to oral glucose tolerance test (OGTT) during pregnancy, and pregnancy outcome in eligible women stratified according to study participation. Of 750 eligible women with a self-reported BMI > 30 kg/m(2), and a live singleton pregnancy, 510 were eligible for inclusion and 425 were randomized to either active intervention (n= 284) or to standard obstetric care (n= 141) including two standard OGTT. The 85 women who declined participation or were excluded due to competing diseases and 240 women who did not respond to the initial invitation received the same standard care. RESULTS The randomized women had similar BMI but a lower parity and age, and were more frequently non-smokers, born in Denmark and married or cohabitating with their partner than the non-participants. Women participating in the trial had a higher compliance to the second OGTT compared to non-participants, also after correcting for age and nationality. There was no difference in pregnancy outcome, i.e., fetal weight and length, gestational age as well as mode of delivery. CONCLUSION Women declining participation in a randomized lifestyle intervention study in pregnancy have characteristics indicating they are those who might benefit the most from lifestyle intervention.