Linda Englund Ögge1,2, Fiona Murray3, Dominika Modzelewska1, Robert Lundqvist4, Staffan Nilsson5,6, Helena Carré7, Maria Kippler8, Agnes E Wold9, Ann-Sofie Sandberg10, Anna Sandin11, Bo Jacobsson1,2, Malin Barman8,10. 1. Department of Obstetrics and Gynecology, Sahlgrenska University Hospital, Gothenburg, Sweden. 2. Department of Obstetrics and Gynaecology, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. 3. Department of Odontology, Norrbotten County Council, Sunderby Research Unit, Umeå University, Umeå, Sweden. 4. Department of Public Health and Clinical Medicine, Norrbotten County Council, Sunderby Research Unit, Umeå University, Umeå, Sweden. 5. Department of Mathematical Sciences, Chalmers University of Technology, Gothenburg, Sweden. 6. Department of Laboratory Medicine, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden. 7. Department of Clinical Sciences, Obstetrics and Gynecology, Sunderby Research Unit, Umeå University, Sweden. 8. Institute of Environmental Medicine, Karolinska Institutet, Stockholm, Sweden. 9. Department of Infectious Diseases, Institute of Biomedicine, The Sahlgrenska Academy, University of Gothenburg, Sweden. 10. Department of Biology and Biological Engineering, Food and Nutrition Science, Chalmers University of Technology, Gothenburg, Sweden. 11. Department of Clinical Science, Pediatrics, Sunderby Research Unit, Umeå University, Umeå, Sweden.
Abstract
BACKGROUND: Prospective birth cohorts are essential for identifying associations between exposures and outcomes. However, voluntary participation introduces a potential bias due to self selection since the persons that chose to participate may differ in background characteristics and behaviors. OBJECTIVES: To investigate potential bias due to self-selection in the Nutritional impact on Immunological maturation during Childhood in relation to the Environment (NICE) birth cohort in northern Sweden. METHODS: Women in the NICE birth cohort (N = 621) were compared to nonparticipating pregnant women in Norrbotten County in northern Sweden who were eligible for participation (N = 4976) regarding maternal characteristics and lifestyle. Maternal characteristics and pregnancy outcomes were compared between the groups and associations between exposures (smoking, folic acid, BMI, parity, education) and pregnancy outcomes (birth weight and gestational age) were analyzed by linear regression analyses, examining any interaction with the group. RESULTS: NICE participants were more highly educated, older and more likely to cohabit than the non-participants. They more often took folic acid and multivitamin supplements and less often smoked during early pregnancy. Pregnancy outcomes (mode of delivery, gestational age at delivery, birth weight and APGAR score) did, however, not differ significantly between participants and non-participants. Smoking, BMI, education and parity affected gestational age and birth weight, but the associations were of similar magnitude in participants and non-participants, with no significant effect on the group. CONCLUSION: Self-selection to the NICE study was evident in some factors related to lifestyle and socioeconomic characteristics but did not appear to skew pregnancy outcomes or alter well-known effects of certain lifestyle parameters on pregnancy outcomes.
BACKGROUND: Prospective birth cohorts are essential for identifying associations between exposures and outcomes. However, voluntary participation introduces a potential bias due to self selection since the persons that chose to participate may differ in background characteristics and behaviors. OBJECTIVES: To investigate potential bias due to self-selection in the Nutritional impact on Immunological maturation during Childhood in relation to the Environment (NICE) birth cohort in northern Sweden. METHODS: Women in the NICE birth cohort (N = 621) were compared to nonparticipating pregnant women in Norrbotten County in northern Sweden who were eligible for participation (N = 4976) regarding maternal characteristics and lifestyle. Maternal characteristics and pregnancy outcomes were compared between the groups and associations between exposures (smoking, folic acid, BMI, parity, education) and pregnancy outcomes (birth weight and gestational age) were analyzed by linear regression analyses, examining any interaction with the group. RESULTS: NICE participants were more highly educated, older and more likely to cohabit than the non-participants. They more often took folic acid and multivitamin supplements and less often smoked during early pregnancy. Pregnancy outcomes (mode of delivery, gestational age at delivery, birth weight and APGAR score) did, however, not differ significantly between participants and non-participants. Smoking, BMI, education and parity affected gestational age and birth weight, but the associations were of similar magnitude in participants and non-participants, with no significant effect on the group. CONCLUSION: Self-selection to the NICE study was evident in some factors related to lifestyle and socioeconomic characteristics but did not appear to skew pregnancy outcomes or alter well-known effects of certain lifestyle parameters on pregnancy outcomes.
Authors: Klara Gustin; Marie Vahter; Malin Barman; Bo Jacobsson; Helena Skröder; Helena Filipsson Nyström; Anna Sandin; Ann-Sofie Sandberg; Agnes E Wold; Maria Kippler Journal: J Nutr Date: 2022-07-06 Impact factor: 4.687