Elevated risk of attention deficit hyperactivity disorder (ADHD) in Japanese children with higher genetic susceptibility to ADHD with a birth weight under 2000 g

Table 3 Association of birth weight categories and genetic risk with ADHD total score among Japanese children at age 8–9 years (N=659) (a total of 137 children with missing information on PRS was excluded from this analysis)

Birth weight and genetic risk of ADHD	Rate ratio (95% confidence intervals)
Birth weight and genetic risk of ADHD	Model 1^†	Model 2^‡	Model 3^§
Normal birth weight
Low risk (ref.)	1.00	1.00	1.00
High risk	0.98 (0.82–1.16)	0.97 (0.83–1.14)	0.98 (0.83–1.15)
Birth weight 2000–2499 g
Low risk	0.88 (0.56–1.37)	1.04 (0.68–1.61)	1.04 (0.68–1.61)
High risk	0.85 (0.55–1.31)	0.88 (0.56–1.38)	0.87 (0.56–1.37)
Birth weight <2000 g
Low risk	1.32 (0.83–2.09)	1.32 (0.80–2.19)	1.30 (0.79–2.16)
High risk	1.82 (1.10–3.01)*	1.68 (1.17–2.39)**	1.64 (1.14–2.35)**

Note: Normal birth weight was defined as birth weight ≥ 2500 g; ref., reference category; values in bold show statistical significance; **p<0.01; *p<0.05
^†Model 1 was adjusted for variations in survey time only
^‡Model 2 additionally adjusted for gender of child, parity, maternal age, education, pre-pregnancy body mass index, pre-pregnancy smoking status, and alcohol intake
^§Model 3 additionally adjusted for father’s age at birth and household annual income

ISSN: 1741-7015