Following 3 cohorts with prospective exposure assessment were included: the Korean Mothers and Children's Environment Health Korea Study (MOCEH, recruiting period 2006-2011), the Norwegian Mother and Child Cohort Study (MoBa, 2004-2008) and the Spanish Environment and Childhood Project (INMA, 2003-2008).
Additionally, following 2 cohorts with retrospective exposure assessment were included: the Danish National Birth Cohort (DNBC, 1996-2002) and the Amsterdam Born Children and their Development Study (ABCD, 2003-2004).
Child behavioral problems reported by mothers were assessed by using the Strengths and Difficulties Questionnaire or Child Behavior Checklist and were classified in the borderline/clinical or clinical ranges.
|Reference group 1||maternal mobile phone use during pregnancy: 0 - 1 calls/day (low)|
|Group 2||maternal mobile phone use during pregnancy: none|
|Group 3||maternal mobile phone use during pregnancy: 2 - 3 calls/day (medium)|
|Group 4||maternal mobile phone use during pregnancy: ≥ 4 calls/day (high)|
In this study population of 83,884 mother-child pairs, 6.6% of children scored for having overall behavioral problems in the borderline/clinical range with 2.7% scoring within the clinical range.
Overall, 38.8% of mothers reported no mobile phone use during pregnancy (largely driven by 30,419 mothers in the Danish cohort reporting no mobile phone use (60.8%). 5.7% of mothers were classified as high mobile phone users.
Evidence for a trend of increasing risk of child behavioral problems through the maternal mobile phone use categories was observed for hyperactivity/inattention problems (problems in the clinical range in group 3: OR 1.11, CI 1.01-1.22, in group 4: OR: 1.28, CI 1.12-1.48). This association was fairly consistent across cohorts and between cohorts with retrospectively and prospectively collected mobile phone use data.
The authors conclude that maternal mobile phone use during pregnancy may be associated with an increased risk for behavioral problems, particularly for hyperactivity/inattention problems, in the offspring. The interpretation of these results is unclear as uncontrolled confounding may influence both maternal mobile phone use and child behavioral problems.