Pregnancy and peripartum risk factors associated with childhood ADHD

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1. As compared to controls, mothers of children with attention-deficit/hyperactivity disorder (ADHD) were significantly more likely to have had threatened preterm labor, threatened abortion, urinary tract infection during pregnancy, preeclampsia, induction of labor, no labor, and cesarean delivery.

2. Girls with ADHD were 2.5 times more likely than those without ADHD to have had cord prolapse at birth, while boys with ADHD were more likely to have presented in the breech position at birth. Oxytocin augmentation, not oxytocin induction of labor, was associated with a decreased risk of ADHD in girls. 

Evidence Rating Level: 3 (Average)

Study Rundown: Attention-deficit/hyperactivity disorder (ADHD) is the most common childhood mental health disorder. While ADHD has a known genetic component, environmental factors also play an important role in mediating the impact of underlying influences. This large case-control study examined the potential association of specific prenatal and perinatal environmental factors with subsequent ADHD diagnoses in the child. Results indicated that, compared to matched controls, mothers of children with ADHD were significantly more likely to be younger, single, smoked during pregnancy, and have had threatened pre-term labor, threatened abortion, a urinary tract infection (UTI) during pregnancy, preeclampsia. Induction of labor, no labor, and cesarean deliveries were associated with an increased risk of ADHD. Among girls, oxytocin augmentation was associated with decreased ADHD risk, while cord prolapse was associated with significantly increased ADHD risk. Among boys, breech presentation was linked to increased ADHD risk. One limitation of this study was the lack of data on parental health, leaving potential family history of ADHD unaccounted. Also, the control population consisted of children who were not prescribed stimulant medication in 2003, although some may have qualified for an ADHD diagnosis. These findings imply that expectant mothers should be aware of the prenatal and perinatal risks associated with ADHD.

Click to read the study published today in Pediatrics

Relevant Reading: Measured Gene-by-Environment Interaction in Relation to Attention-Deficit/Hyperactivity Disorder

Study Author, Dr. Desiree Silva, MBBS, FRACP, MPH, talks to 2 Minute Medicine: Consultant Pediatrician, Joondalup Health Campus, School of Pediatrics and Child Health, University of Western Australia, Perth, Australia.

“ADHD is the commonest mental health disorder in childhood. There is a strong genetic predisposition to ADHD, as well as some evidence of early environmental factors playing a part. Our study was one of the largest population studies of 12 991 children diagnosed with ADHD using the DSMIV /ICD10 criteria and 30 070 non ADHD controls.  We found that mothers of ADHD children were significantly more likely to be younger, single, smoked in pregnancy, had labour induced, experience threatened pre-term labour, pre-eclampsia, and urinary tract infection in pregnancy, with little difference between gender. There was a small increased risk by prematurity even when born early term (37-38 weeks gestation). There was no increased risk for low birth weight, low Apgar sores and fatal distress, although there was nearly a three fold increase for the rare cord prolapse in females.

It is important that mothers recognize the risk of ADHD associated with smoking in pregnancy and the small increased risk associated with prematurity. Attention to maternal infections and pre-eclapsia may also reduce this risk.”

In-Depth [case-control study]: Individuals born in Western Australia since January 1, 1980, under 25 years of age, and who were prescribed stimulant medication for ADHD between 2003 and 2007 were included as study participants. In total, there were 12 991 cases and 30 071 matched controls (77% overall male). The groups were matched by gender, birth year, and socioeconomic status. Mothers of children with ADHD were more likely to be younger (< 20 years old), single, and smokers during pregnancy, regardless of child gender (OR = 1.57, 1.50, and 2.06 respectively, for males, OR = 1.57, 1.55, and 1.73 respectively, for females). As compared to controls, mothers of children with ADHD were significantly more likely to experience threatened pre-term labor (OR = 2.46 for boys, 2.09 for girls) and threatened abortion (OR = 1.15 for boys, 1.28 for girls). In addition, mothers of children with ADHD were more likely to have had a UTI during pregnancy (OR = 1.37 for boys, 1.51 for girls) or pre-eclampsia (OR = 1.32 for boys, 1.44 for girls). Mothers who had induced labor, no labor, and both elective and emergency cesarean deliveries all had an increased risk of ADHD. For girls, oxytocin augmentation was associated with a decreased risk (OR = 0.58), while cord prolapse was associated with a significantly increased risk for ADHD (OR = 2.50). In boys, breech presentation had an increased risk of ADHD (OR = 1.17).

By Cordelia Y. Ross and Leah H. Carr

More from this author: Consistent parenting linked to lower child BMI; Cough medicine-related ED visits linked to unsupervised ingestion; Shared decision-making associated with increased parental resistance to vaccinations; AAP policy statement addresses influence of media on children; Pediatric gunshot injuries associated with higher mortality and costs

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