Table 6. Association between in-utero lamotrigine exposure and the endpoints duration of pregnancy and size at birth.

	Exposed to High/Low Dose, n/n	Difference (95% CI)				Odds Ratio (95% CI)
		Mean	10th Percentile	50th Percentile	90th Percentile
		Pregnancy duration (days)				Preterm birth
High vs. low dose of lamotrigine	551 / 547	-1.8 (-3.8 to 0.2)	-0.9 (-5.1 to 3.3)	-0.6 (-2.6 to 1.3)	-1.1 (-3.2 to 1.0)	1.3 (0.7 to 2.2)
		Birth weight z-score				SGA
High vs. low dose of lamotrigine	557 / 557	0.1 (-0.1 to 0.2)	-0.0 (-0.3 to 0.2)	0.1 (-0.0 to 0.3)	0.1 (-0.1 to 0.3)	0.9 (0.3 to 2.1)
		Birth length z-score
High vs. low dose of lamotrigine	548 / 551	0.1 (-0.1 to 0.2)	-0.1 (-0.3 to 0.2)	-0.0 (-0.2 to 0.1)	0.3 (0.1 to 0.5)
		Birth head circumference z-score				Microcephaly
High vs. low dose of lamotrigine	543 / 550	0.0 (-0.1 to 0.2)	-0.1 (-0.4 to 0.1)	-0.0 (-0.2 to 0.2)	0.0 (-0.2 to 0.3)	0.5 (0.2 to 1.6)

AED, antiepileptic drug; CI, confidence interval; SGA, small for gestational age.

AED use was ascertained at any time in pregnancy. The reference was the bottom tertile of mean daily dose of lamotrigine (2006–2013). All results were adjusted for birth year, maternal age at delivery, education, country of origin, marital status, body mass index, smoking in current pregnancy, alcohol dependence, diabetes, hypertension, epilepsy, depression, bipolar disorder, migraine, chronic pain, and other psychiatric disorders.