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Identification of response bias on apparent pregnancy outcome after second trimester ultrasound
Author(s) -
Kozlowski Peter,
Stressig Ruediger,
Hammer Ruediger,
Siegmann Hans Joerg,
Froehlich Susanne,
Verde Pablo Emilio,
Knippel Alexander Johannes
Publication year - 2011
Publication title -
prenatal diagnosis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.956
H-Index - 97
eISSN - 1097-0223
pISSN - 0197-3851
DOI - 10.1002/pd.2758
Subject(s) - medicine , confidence interval , odds ratio , pregnancy , obstetrics , logistic regression , gynecology , pediatrics , biology , genetics
Objectives To investigate whether there is a response bias in outcome studies after prenatal ultrasound and to quantify this potential effect by information source. Materials and methods All normal ultrasound scans between week 17 and week 24 and 6 days performed in the years 2004 and 2005 were investigated. A multinomial logistic regression model was applied to investigate the association between responders' outcome (questionnaire, phone interview and inquiry to birth clinic) and the following explanatory variables: maternal age, smoking status, body mass index, congenital anomaly status, low birthweight and preterm deliveries. Results From the 12 439 women, 7747 (62.3%) sent back the questionnaire, 3032 (24.4%) were interviewed by telephone and in 1660 cases (13.3%) the outcome was obtained from the birth clinic. Maternal age > 34 years [odds ratio (OR) 0.72, confidence interval (CI) 0.61‐0.85/0.35, CI 0.29‐0.42, telephone/birth clinic] and minor anomalies (OR 0.52, CI 0.28‐0.98, birth clinic) were significantly underrepresented in nonresponders. Preterm delivery (OR 1.29, CI 1.11‐1.50/1.30, CI 1.08‐1.57), maternal smoking (OR 1.14, CI 1.07‐1.25/1.31, CI 1.22‐1.40) and stillbirths (OR 2.30, CI 1.09‐4.87, birth clinic) were significantly, major anomalies (OR 1.83, CI 0.94‐3.55/1.80, CI 0.79‐4.10) were considerably overrepresented in these groups. Conclusion Spontaneous responding to prenatal follow‐up questionnaires is significantly biased towards older and nonsmoking mothers with normal pregnancy outcome. Copyright © 2011 John Wiley & Sons, Ltd.