Elevated level of prenatal testosterone and vitamin D3 deficiency during pregnancy, in the presence of prenatal maternal stress, and their association with the development of attention deficit hyperactivity disorder (ADHD)-like symptoms in toddlers

Introduction
To investigate the hypothesis that the presence of prenatal maternal stress, increased level of prenatal testosterone, and low level of vitamin D3 in pregnancy is associated with the development of ADHD-like symptoms in toddlers (< 2 years old).

Material and methods
The study group comprised 53 pregnant women and 53 infants of these pregnancies. The population cohort of 53 pregnant women were recruited at their 35th to 37th week of pregnancy and investigated prospectively. The participants were selected through targeted selection. Maternal experience of stressful life events was assessed by stress standardised questionnaires, prenatal testosterone was determined in the mothers’ saliva by using the immune enzymatic (ELISA) method, and maternal plasma D vitamin was measured using the ECLIA method, during pregnancy. When the age of the offspring was 6 months and then less than 2 years, the mothers completed the child behaviour and temperament checklist.

Results
A small but statistically significant association was found between the common symptom complex of ADHD and the level of testosterone and vitamin D3, in the presence of prenatal maternal stress. Multiple regression analysis showed that maternal stressful events during pregnancy significantly predicted ADHD behaviours in offspring.

Conclusions
The study supported the hypothesis that prenatal maternal stress, increased level of prenatal testosterone, and low level of vitamin D3 during pregnancy increases the risk of development of ADHD-like symptoms in toddlers (< 2 years old). Also, the obtained results support the hypothesis that the influence of prenatal factors causes ADHD-like symptoms in offspring through a programming effect.