Children in the prenatal-exposure group were more likely to be born pre-term when compared to the general percentage of preterm births in the participating countries (it was not possible to compare to the control group as they were matched according to gestational age). The prenatal exposure group also had a higher percentage of babies born small for gestational age (22.0% vs. 15.2% in the control group), although the difference was not statistically significant (P=0.16).
The authors of a related editorial note the limited data available on the effects of chemotherapy during pregnancy. The quality and completeness of the available data are limited and frequently lack critical information such as dose, timing of administration during gestation, maternal complications and follow-up beyond the immediate post-natal period. As cancer among pregnant women is so rare, it takes quite a while to accumulate enough information to be confident about which toxic effects (including malformations) are associated with particular agents.
The researchers caution that their findings cannot be extrapolated to all cancer drugs (especially the newer targeted agents) and the follow-up was too short to document longer-term effects that may become more apparent in later life (e.g. cardiotoxicity; neurocognitive problems).
They go on to conclude from their results that a diagnosis of cancer during pregnancy is not necessarily an indication to terminate the pregnancy. The editorial states that these findings should be reassuring to women facing a new cancer diagnosis during pregnancy; however prudence continues to suggest avoiding cancer treatment in the first trimester.