Objective: To test the null hypothesis of no association between ultrasound exposure in early fetal life and impaired neurologic development in childhood.
Methods: Study of children age 8-9 years whose mothers participated in a randomized controlled trial of ultrasound screening during pregnancy in Sweden during 1985-1987. Of 4637 eligible singletons, 3265 (70%) were studied through a questionnaire to their mothers. Assessment of neurologic development was based on parents' report of their child's speech and motor development. Behavioral disorders were assessed by a ten-item parent scale. Analyses were performed according to both assignment and ultrasound exposure. With a sample size of 1600 children in each group, a two-sided alpha of .05 and beta of .10, a risk ratio of less than 1.4 for the studied variables could not be detected.
Results: Delayed speech development was reported by 2.9% in the screening group compared with 2.4% in the nonscreening group (odds ratio [OR] 1.21; 95% confidence interval [CI] 0.79, 1.88). Similar prevalences were found when analysis was according to ultrasound exposure (OR 1.19, 95% CI 0.78, 1.83). Delayed motor development was reported by 7.6% in the screening group compared with 7.2% in the nonscreening group (OR 1.05; 95% CI 0.81, 1.37). Corresponding figures for ultrasound-exposed and -unexposed were 7.7% and 7.2%, respectively (OR 1.08; 95% CI 0.83, 1.40). There also were no significant differences in behavioral disorders between screened and unscreened children or between exposed and unexposed children, respectively, according to parents' ratings.
Conclusion: No significant difference in impaired neurologic development between ultrasound-exposed and -unexposed children was found in this study.