To evaluate whether children with neurofibromatosis type 1 (NF1) and tuberous sclerosis have different birth characteristics compared with the general population.

We identified all individuals born in Sweden between 1973 and 2014 from the nationwide Medical Birth Register for whom information on both biological parents was available (n = 4 242 122). Individuals with NF1 and individuals with tuberous sclerosis were identified using data from Swedish population-based health data registers. Using logistic regression models, we assessed the associations between these 2 neurocutaneous syndromes and birth characteristics in a cohort that included 1804 subjects with NF1 and 450 with tuberous sclerosis.

Children with NF1 and tuberous sclerosis were significantly more likely to be born preterm and via cesarean delivery. In addition, children with NF1 were also more likely to be born with other birth characteristics, such as short length, a large head circumference, and a low Apgar score. Moreover, children with NF1 had an increased odds of being born with a high birth weight or large for gestational age (OR, 1.61; 95% CI, 1.42-1.82 and OR, 1.82; 95% CI, 1.60-2.06, respectively).

Children with NF1 and tuberous sclerosis differ from the general population in terms of several birth characteristics, with the strongest associations observed for high birth weight and large for gestational age in individuals with NF1.