Sex-specific and time-dependent effects of prenatal stress on the early behavioral symptoms of ADHD: a longitudinal study in China.

There is increasing evidence that prenatal stressful life events (SLEs) may be a potential risk factor for attention-deficit hyperactivity disorder (ADHD), but the sex-specific and time-dependent effects of prenatal stress on ADHD are less clear. In this prospective longitudinal study, data on prenatal SLEs during different stages of gestation and indicators of buffers against stress, including maternal social support and avoidance coping, were obtained from 1765 pregnant women at 32 weeks of gestation. The behavioral symptoms of ADHD in children aged 48-54 months were evaluated by reports from the parents. There were 226 children (12.8%) above the clinically significant cutoff for ADHD. After adjusting for potential confounders, boys whose mother experienced severe SLEs in the second trimester had a significantly increased risk (OR = 2.41, 95% CI: 1.03-5.66) of developing ADHD symptoms compared with boys whose mothers did not experience severe SLEs at this time. However, no significantly increased risk of ADHD symptoms was observed in girls born to mothers experienced prenatal severe SLEs. Additionally, significant interaction effects of prenatal SLEs, social support and coping style on ADHD symptoms were found in males. Boys whose mothers experienced severe SLEs during the second trimester accompanied by a higher score for avoidance coping (OR = 3.31, 95% CI: 1.13-9.70) or a lower score for social support (OR = 4.39, 95% CI: 1.05-18.31) were likely to be at a higher risk for ADHD symptoms. The epidemiological evidence in this prospective follow-up study suggests that the effect of prenatal SLEs on ADHD symptoms in offspring may depend on the timing of prenatal stress and may vary according to the sex of the offspring.