Laursen RP, Larnkjær A, Ritz C, et al. - Researchers explored the links between thymus size and anthropometric measurements, gender, age, the status of breastfeeding, presence of siblings, household pets, and infections and allergies since birth in healthy Danish infants aged 8-13 months. They used information from 256 healthy infants registered in the ProbiComp study. The thymus size was measured using sonographic measurements, and the thymic index (TI) and thymus weight index (TWI) were used respectively as an absolute and relative volume calculation. In terms of TI and TWI boys, the thymus was about 15% and 5% larger than girls. Findings suggested an association of thymus size with current breastfeeding in girls and with having household pets in boys. In future studies on factors related to thymus size, sex-specific associations should be further examined. No other thymus size-related factors have been identified.