Chemotherapy during pregnancy is not harmful

It will happen to you. You are pregnant and diagnosed with cancer. While in the past pregnancies were sometimes terminated due to this diagnosis, there is good news: chemotherapy may be used from 14 weeks of pregnancy without harmful consequences for the fetus. This is evident from a study at KULeuven.


Cancer symptoms are sometimes masked by the physical changes that occur during pregnancy. As a result, the diagnosis can often only be established at an advanced stage. The most common cancers during pregnancy are breast cancer and hematological cancers.
Research showed that terminating the pregnancy does not improve the woman’s prospects: the disease follows the same course. The pregnancy does not have to be terminated due to a cancer diagnosis, provided the correct treatment is given. It is of course important that the treatment plan is drawn up by a multidisciplinary team where the safety of the fetus comes first. Chemotherapy can be safely administered from 14 weeks.

European research

The study at KULeuven is part of a broader European study in which 503 women are being followed. About 70 children are examined at different times by researchers at the KULeuven.

  • Newborns: standardized clinical neurological examination
  • 18 months: Bayley score
  • 6 years: IQ test, audiometry, neuropsychological test battery for working memory and attention
  • 9 years: same as 6 years + Evoked Related Potentials test
  • Afterwards: 3-yearly check-up

At each evaluation moment, an examination of the heart is also performed via electrocardiography and echocardiography.

Placenta as a filter

One of the most important results of this study is that it was established that the fraction of chemotherapy that reaches the fetus is very limited. It could be shown that the placenta acts as a filter and thus protects the fetus against the toxic influence of chemotherapy.


The mothers were treated with chemotherapy during pregnancy, whether or not combined with radiotherapy or surgery, for various tumor types. The average age of the children involved is just over 2 years. 47 of the 70 children studied were born prematurely. The average gestational age at the birth of the children was 36 weeks. There were 2 twin pregnancies.
The first results on 70 children aged 18 months or older are reassuring. Children who are prenatally exposed to chemotherapy do as well as their peers who were not exposed. At birth they do not show more abnormalities than other babies and their further development is comparable to the average development of other children.
A developmental disorder was found in only 1 twin, which is probably due to premature birth (33 weeks). Researchers therefore advocate not initiating birth, but continuing the pregnancy until at least 37 weeks, if this is not really necessary.

Better advice

This research is of great importance because it allows better advice to pregnant women with cancer. Because the results are positive, the women can be reassured. Termination of pregnancy due to a cancer diagnosis is no longer necessary and patients no longer have to fear any negative consequences for their child.


To date, children with an average age of 2 years have been studied. Researchers point out the importance of continuing and expanding this project. Other consequences, such as effects on fertility and the risk of developing cancers later in life, are not yet known. It will only be within ten years that it can be established that prenatal exposure to chemotherapy is not harmful, even in later stages of life.
The results of this study were presented at the European Multidisciplinary Cancer Conference in September 2011 in Stockholm.

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