A pioneering Israeli study has identified a link between pregnancy-associated cancer and an increased risk of long-term illness among offspring.
At the recent 2026 American Society for Clinical Oncology (ASCO) Annual Meeting in Chicago, Illinois Professor Irit Ben Aharon, Director of the Joseph Fishman Oncology Center at Rambam Health Care Campus (Rambam) presented the results of a pioneering study on the long-term health risks in children born to mothers diagnosed with cancer during pregnancy. The study reveals that these children face a greater risk of developing chronic diseases than their peers in the general population, including inflammatory bowel disease, asthma, allergies, and cardiovascular disease, with the average onset emerging in their twenties.
Scientists from Rambam, the Clalit Research Institute, Beilinson Hospital (Rabin Medical Center), and Tel Aviv University collaborated on the study. The study was comprised of a preclinical part and an epidemiological part, in which the team analyzed healthcare data from 3,561 women diagnosed with cancer while pregnant and their offspring, alongside a control group of 28,361 women and their offspring.
“This is the first time we have been able to conduct a long-term study of this nature,” says principal investigator Professor Irit Ben-Aharon who presented the data at the ASCO meeting.
Their findings show that children born after in utero exposure to maternal cancer face a 16% higher risk of developing inflammatory bowel diseases such as Crohn’s disease and colitis, a 20% higher risk of allergic conditions. “For years, clinicians have questioned whether children born to mothers diagnosed with cancer during pregnancy face increased health risks but former evidence relied on follow up time that was only until childhood and early adolescence,” Ben-Aharon explains. “We found that the difference in morbidity compared with the general population becomes apparent in their twenties, rather than during childhood.”
The study indicated also a general rise in the incidence of cancer during pregnancy, presumably due to increasing cancer rates among younger adults and delayed parenthood.
Alongside the epidemiological study, the team conducted laboratory research examining chemotherapy’s effects during fetal development. Their findings presented by Prof. Ben-Aharon and her team at the recent annual European Association for Cancer Research (EACR) meeting, showed that chemotherapy can directly cross the placenta and induce in some of the embryos possible epigenetic signature on fetal DNA. These epigenetic changes may influence gene activity throughout life and could help explain the increased morbidity observed later in adulthood.
Scientists still do not fully understand why illness develops in some of these children and continue laboratory investigations to better understand the underlying mechanism. Their leading hypothesis suggests that these diseases share a common inflammatory pathway underlying the delayed spectrum of morbidities, which manifests in only a small percentage of individuals 20–30 years after exposure.
“These findings may change the way we consider children exposed to cancer while in utero from the healthcare perspective” says Ben-Aharon. “Today, structured follow-up programs exist for childhood-cancer survivors, but children whose mothers had cancer during pregnancy are not considered to be monitored at all by the healthcare system due to lack of evidence for a risk. This study may be the first step toward changing that.”
Israel’s unique medical databases made this breakthrough possible by enabling researchers to link maternal and child health records. “This research shed a light on those who may be prone to develop late-onset diseases and who, for now, remain under the radar and receive no structured follow-up.”
Read the study that appeared in the Journal of Clinical Oncology 2026;44:11013
Based on an original Hebrew article that first appeared in Israel Hayom.
