Table 4.

Risk Ratios for Parent- and Child-Reported Behavioral Difficulties Assessed by Strengths and Difficulties Questionnaire at Age 11 Years According to Prenatal Exposure Timing to Acetaminophen in the Danish National Birth Cohort, 1996–2002

Outcome	Score	First Trimester Only (n = 4,366)		Second Trimester Only (n = 2,219)		Third Trimester Only (n = 3,992)		Any 2 Trimesters (n = 5,530)		All 3 Trimesters (n = 3,528)
		Adjusted Risk Ratiosa	95% CI	Adjusted Risk Ratiosa	95% CI	Adjusted Risk Ratiosa	95% CI	Adjusted Risk Ratiosa	95% CI	Adjusted Risk Ratiosa	95% CI
Parent-reported
SDQ total difficulties	≥17	1.08	0.89, 1.31	0.91	0.69, 1.21	1.06	0.86, 1.31	1.22	1.03, 1.45	1.20	0.98, 1.46
Internalizingb	≥8	1.07	0.93, 1.24	1.00	0.82, 1.22	1.04	0.89, 1.21	1.12	0.99, 1.28	1.09	0.94, 1.27
Externalizingb	≥8	1.07	0.95, 1.21	0.91	0.77, 1.08	1.05	0.93, 1.18	1.09	0.98, 1.21	1.11	0.98, 1.26
Child-reported
SDQ total difficulties	≥17	1.50	1.19, 1.88	1.09	0.78, 1.53	1.33	1.03, 1.71	1.17	0.94, 1.46	1.53	1.19, 1.96
Internalizingb	≥9	1.11	0.96, 1.27	1.17	1.02, 1.35	1.17	1.02, 1.35	1.05	0.93, 1.20	1.25	1.08, 1.44
Externalizingb	≥9	1.07	0.95, 1.21	1.02	0.86, 1.19	1.18	1.05, 1.33	1.15	1.03, 1.28	1.16	1.02, 1.32

Abbreviations: CI, confidence interval; SDQ, Strengths and Difficulties Questionnaire.

^a Adjusted for maternal age at birth, child’s birth year, parity, socio-occupational status of mother, maternal prepregnancy body mass index, maternal smoking, alcohol drinking during pregnancy, mother’s ever having had mental health problems, maternal diseases in muscles/joints, fever or infection/inflammation during pregnancy, and NSAIDs intake during pregnancy. Reference was never-user (n = 19,264).

^b Defined by 95th percentile of each composite score.