Exposure to chemotherapy late in pregnancy had little effect on placenta

The timing and type of chemotherapy used during pregnancy resulted in differing effects on the placenta, according to data from a recently published study.

Researchers took data from patient files at the Women and Infant’s Hospital in Rhode Island from 1990 to 2007. Details for chemotherapy administration, the type of malignancy and the outcome of the pregnancy were reviewed.

Inclusion criteria were exposure to chemotherapeutic agents during pregnancy and the availability of the placenta. Thirteen women, aged 17 years to 40 years, were included in the study.

Ten women were treated with various DNA-active cytotoxic agents during their second or third trimesters; one woman was treated with cytotoxic chemotherapeutic agents throughout the entire pregnancy. One patient received the targeted tyrosine kinase inhibitor, imatinib (Gleevec, Novartis), during two consecutive pregnancies.

Results for the 10 women treated with DNA-active cytotoxic agents during their second or third trimesters indicated non-specific findings with no congenital anomalies. Thirty-six percent of the placentas were small-for-gestational age.

The woman treated with cytotoxic chemotherapeutic agents throughout the entire pregnancy had labor induced at 32 weeks’ gestation. The pregnancy had several congenital anomalies including cleft lip and palate. The placenta showed striking nuclear pleomorphism of the extravillous trophoblast of the chorion laeve.

No specific anomalies were found for the placentas of the woman treated with imatinib during two consecutive pregnancies and both placentas were appropriate for age. – by Jennifer Southall

Abellar RG. Pediatr Dev Pathol. 2009;doi:10.2350/08-03-0435.1

This work is extremely important because until now the focus was on congenital malformations in the baby, which are occurring when exposure occurs in the first trimester. Yet, repeated studies have shown that when the mother is treated with chemotherapy in late pregnancy there is more risk of intrauterine growth retardation and stillbirth. The placenta continues to grow throughout pregnancy and therefore the effects of chemotherapy on placental growth and hormonal function have to be studied in order to minimize fetal damage. While the present study did not show major changes in morphology, future studies should focus on placental functions, which may be affected without major morphological changes.

– Gideon Koren, MD

Director, The Motherisk Program
The Hospital for Sick Children, Toronto