Incidence of neonatal neutropenia and leukopenia after in utero exposure to chemotherapy for maternal cancer

Objective: The main purpose of this article was to report the incidence of neonatal neutropenia or leukopenia after chemotherapy exposure during pregnancy according to the time elapsed between treatment during pregnancy and birth. Background: A single study reports 33% of infants exposed to chemotherapy within the last month of pregnancy are born with neutropenia, which can place the newborn at risk for nosocomial infections. On the basis of this report, chemotherapy is typically stopped by 34 weeks of pregnancy to avoid maternal or neonatal myelosuppression at delivery. Such a pause in treatment may affect maternal health. Determining the true incidence of neutropenia after chemotherapy in relation to the time of this lapse in treatment is important to support this practice. Materials and Methods: Complete blood counts are collected for newborn whose mothers were treated for cancer during pregnancy and enrolled in the Cancer and Pregnancy Registry. Neutropenia was defined as absolute neutrophil count< 1000 mm3 and leukopenia was defined as white blood cells < 5000 cells /μL. Incidence of neutropenia was calculated according to the time elapsed from last chemotherapy treatment until birth. Fisher's exact test is used to determine if neutropenia or leukopenia is related to the time elapsed between chemotherapy during pregnancy and newborn birth. A Bayesian analysis evaluated the occurrence of neutropenia and leukopenia according to the number of days between the initiation of chemotherapy and birth. Results: A total of 135 infants exposed to chemotherapy in utero with a complete blood count collected at birth were identified from the database. Only 7.3% and 2.9% of infants were born with neutropenia or leukopenia, respectively. The highest incidence of newborn neutropenia occurred in infants delivered 22 to 28 days after chemotherapy. Conclusions: The incidence of neutropenia peaks when chemotherapy is given 22 to 28 days before birth, while leukopenia is highest if delivery is < 7 days from chemotherapy.