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ProClinS Gynecology and Obstetrics




Cancer occurs in approximately 1:1000 pregnancies. When chemotherapy cannot be delayed until postpartum, beginning chemotherapy is based on presumed safety after organogenesis is completed during the first trimester. The safest gestational age to start chemotherapy after the first trimester is unknown.

Patients and Methods

In an observational cohort of pregnant women diagnosed and treated for cancer at multiple centers, pregnancy outcomes for the mother, and clinical outcomes for the neonate were analyzed according to the gestational age in weeks of pregnancy at first chemotherapy cycle. Outcomes including birth weight, fetal growth restriction, congenital malformations, and perinatal complications for mother and infant were analyzed according to gestational age of chemotherapy initiation. Neonatal growth, general health and developmental assessment were provided annually by each child’s pediatrician. For each outcome, cut-point of gestational age at first chemotherapy after 12 weeks was determined with odds ratios (OR).


Data from 225 women (231 fetuses) were analyzed. Initiating chemotherapy before 15 weeks GA significantly increased risk for intrauterine growth restriction (OR=3.0), before 16.6weeks GA increased risk for congenital anomalies (OR=3.9), and before 18 weeks GA increased risk for spontaneous preterm birth (OR=2.3). Maternal and neonatal complications during pregnancy or follow up were not statistically different based on GA when chemotherapy began.


During the second trimester, the ideal time to start chemotherapy should consider maternal benefit versus neonatal risk. With a history of spontaneous preterm birth in a prior pregnancy, delaying chemotherapy until 18 weeks may decrease recurrent preterm birth, if not detrimental to the mother. The risk for fetal growth restriction increased with chemotherapy initiation before 15 weeks, and for congenital malformations before 17 weeks.

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Creative Commons Attribution 4.0 International License
This work is licensed under a Creative Commons Attribution 4.0 International License.