Certain fertility treatments associated with Kawasaki disease risk in children

A large-scale Japanese study found that certain fertility treatments may increase the risk of Kawasaki disease in children under five, though the link varied based on the treatment type. Published in JAMA Network Open, the research analyzed data from 101,864 children in the Japan Environment and Children's Study, examining Kawasaki disease occurring before age five among those conceived spontaneously or via ovulation induction, intrauterine insemination, in vitro fertilization, or intracytoplasmic sperm injection.

During a five-year follow-up, 1,226 children developed Kawasaki disease. Compared to spontaneous conception, the risk was higher after ovulation induction (adjusted hazard ratio of 1.57), intrauterine insemination (HR of 1.48), and in vitro fertilization (HR of 1.53). Intracytoplasmic sperm injection showed no clear difference in risk (HR of 0.91).

These findings remained consistent after accounting for maternal conditions such as endometriosis, polycystic ovary syndrome, allergic conditions, and autoimmune disease. Senior author Ryo Kawasaki, whose last name matches the disease, noted that further investigation into the association between fertility treatments and Kawasaki disease could help clarify the underlying mechanisms.

The study highlights a nuanced relationship between fertility treatments and child health, showing that the association with Kawasaki disease differs by treatment type. However, the authors stress that the results indicate associations, not causation, and require confirmation in other populations.