Cancer risk in children and young adults conceived by in vitro fertilization.

OBJECTIVES Studies conducted so far have found no statistically significant increased risk for cancer among children who are born after in vitro fertilization (IVF). METHODS We followed 26,692 children who were born after IVF during the years 1982-2005 by using the Swedish Cancer Register and compared the number of children who had cancer and were born after IVF with children who were not conceived by IVF. Adjustment was made for year of birth. RESULTS Maternal age, parity, smoking, subfertility, previous miscarriages, BMI, and multiple births did not significantly affect cancer risk in offspring. High birth weight, premature delivery, and the presence of respiratory diagnoses and low Apgar score were risk factors for cancer. We identified 53 cases of cancer in children who were born after IVF against 38 expected cases: 18 of them with hematologic cancer (15 of them acute lymphoblastic leukemia), 17 with eye or central nervous system tumors, and 12 with other solid cancers. There were 6 cases of Langerhans histiocytosis against 1.0 expected. The total cancer risk estimate was 1.42 (95% confidence interval: 1.09-1.87). CONCLUSIONS We found a moderately increased risk for cancer in children who were conceived by IVF. Putative intermediary factors could be preterm birth and neonatal asphyxia.