Some fertility treatments may raise Kawasaki disease risk in children

A large-scale study in Japan, led by researchers from the University of Osaka and the Osaka Women's and Children's Hospital, has found that certain fertility treatments are associated with an increased risk of Kawasaki disease before age five, although the association differed by treatment type. The findings were published in JAMA Network Open.

Kawasaki disease is a systemic inflammatory disease that primarily affects young children and is a leading cause of acquired heart disease in children. Its exact cause remains unclear.

The research team analyzed data from 101,864 children participating in the Japan Environment and Children's Study (JECS), a nationwide prospective birth cohort. They examined Kawasaki disease occurring before age 5 among children conceived spontaneously or following ovulation induction, intrauterine insemination (IUI), in vitro fertilization (IVF), or intracytoplasmic sperm injection (ICSI).

During the 5-year follow-up, 1,226 children developed Kawasaki disease. Compared with spontaneous conception, the risk was higher following ovulation induction (adjusted hazard ratio [HR], 1.57), IUI (HR, 1.48), and IVF (HR, 1.53). ICSI showed no clear difference in risk (HR, 0.91).

These patterns remained broadly consistent after accounting for maternal conditions including endometriosis, polycystic ovary syndrome, allergic conditions, and autoimmune disease.

"Kawasaki disease remains an important cause of acquired heart disease in children, yet its causes are still not fully understood," Ryo Kawasaki said. "Further investigation of the association between fertility treatments and Kawasaki disease may help clarify the mechanisms underlying the disease."

The results highlight a nuanced relationship between fertility treatments and child health, showing that the association with Kawasaki disease differs by treatment type. The authors emphasize that the findings show associations rather than causation and require confirmation in other populations.