Posted: March 3, 2017

Are there risks to the unborn child if its mother gets chemotherapy during pregnancy?  What about if she just has cancer?  What about the risks of birth defects?  Much has been written about this over the years.   Now from Sweden comes a comprehensive analysis of their experience.  Published in the Journal of Clinical Oncology, click here for the abstract.  Dr. Stark can email you the article if you request it in the form to the right on this page.   The authors reviewed the Swedish national database over a forty year period and reviewed almost four million “singleton” (not twins, etc.) births.   They identified 984 births of women who had cancer diagnosed during pregnancy and 2723 births in the year after the diagnosis.  There was a striking incidence of fetal demise in both groups — over twice what would have been expected — although the absolute number was still very small.   Most of these deaths were in fetuses deemed small for gestational age — i.e, where development was slow.  Curiously they did not have data on which women received chemotherapy, but commented that in Sweden over fifty percent of cancers that develop during pregnancy were “treated” (whatever that means).  So they did not know what additional deleterious effect chemo may have had.  Also they made no attempt to assess the incidence of fetal abnormalities, previously thought common only in offspring of women who had received chemo in the first trimester.

So what do we learn?  Dr. Stark comments, We learn less than we should.  Surely the Swedes should have had the answers that the above analysis shows are lacking.  No one has looked at this many births before this and it seems that a huge opportunity was squandered.  The authors do say that they could not tease out directly the impact of chemo, but since conventionally chemo was withheld until the second trimester and since their data show that the highest fetal loss was in women diagnosed during the second trimester, they are inferring an association.  They also claim without proof that the lower rate of fetal loss in the first trimester is likely from unrecognized spontaneous miscarriage.   No information is given about birth defects.