DNHR

Potential confounding by maternal smoking was evaluated in the cohort of children born after December 31, 1995, when information on maternal smoking during pregnancy was available in DNHR. Statistical analyses were performed using STATA version 11 (Stata Corp., College Station, Texas, USA) and a 5% level of significance was chosen.

Among 1,699,693 liveborn singletons in Denmark between January 1, 1978, and November 30, 2006, we identified 34,582 singletons (2.0%), whose mother had a diagnosis of hyperthyroidism (1.3%) or hypothyroidism (0.7%) registered in DNHR before January 1, 2007.

We identified 5,742 single-tons (0.3%) whose father had a diagnosis of hyperthyroidism (n = 3,981) or hypothyroidism (n = 1,761) registered in DNHR before January 1, 2007, and among these children, 288 (5%) had a diagnosis of seizure (neonatal n = 9, febrile n = 190, and epilepsy n = 109).