Several studies report an association between maternal smoking during pregnancy and offspring
conduct disorder. However, past research evidences difficulty in disaggregating prenatal
environmental influences from genetic and postnatal environmental influences.
To examine the relationship between maternal smoking during pregnancy and offspring conduct
problems among children reared by genetically related mothers and genetically unrelated mothers.
Design, Setting, and Participants
The following 3 studies using distinct but complementary research designs were used: The
Christchurch Health and Development Study (a longitudinal cohort study that includes biological and
adopted children), the Early Growth and Development Study (a longitudinal adoption-at-birth study),
and the Cardiff IVF (In Vitro Fertilization) Study (an adoption-at-conception study among
genetically related families and genetically unrelated families). Maternal smoking during pregnancy
was measured as the mean number of cigarettes per day (0, 1-9, or ≥10) smoked during
pregnancy. Possible covariates were controlled for in the analyses, including child sex, birth
weight, race/ethnicity, placement age, and breastfeeding, as well as maternal education and maternal
age at birth and family breakdown, parenting practices, and family socioeconomic status.
Main Outcomes and Measure
Offspring conduct problems (age range, 4-10 years) reported by parents or teachers using the
behavior rating scales by Rutter and Conners, the Child Behavior Checklist and the Children’s
Behavior Questionnaire Short Form, and the Strengths and Difficulties Questionnaire.
A significant association between maternal smoking during pregnancy and offspring conduct
problems was observed among children reared by genetically related mothers and genetically unrelated
mothers. Results from a meta-analysis affirmed this pattern of findings across pooled study
Conclusions and Relevance
Findings across 3 studies using a complement of genetically sensitive research designs suggest
that smoking during pregnancy is a prenatal risk factor for offspring conduct problems when
controlling for specific perinatal and postnatal confounding factors.