There are no prospective clinical studies evaluating the short- and long-term effects of chemotherapy on pregnancy. Therefore, the data is based on case studies and retrospective studies. Neonatal outcomes including miscarriage, congenital abnormalities, preterm delivery, IUGR, and stillbirth are primarily dependent on gestational age and type of chemotherapeutic agent. There are increased rates of spontaneous abortion in the first 4 weeks and birth defects during weeks 5 to 12 when cytotoxic agents are required. Fetuses exposed in the second and third trimester have the same rate of birth defects as the general population, but exposure has been linked to IUGR, prematurity, and stillbirth.
In the periimplantation and immediate postimplantation period, radiation has an all-or-none effect, resulting in early pregnancy loss or development of normal pregnancy. High-dose radiation exposure is often deferred in pregnancy because it is associated with poor outcomes, including spontaneous abortion, developmental delay, microcephaly, and IUGR. However, radiation has been safely used outside the pelvis with appropriate shielding.
Antenatal fetal well-being should be closely monitored with the consultation of a maternal fetal medicine specialist. Antenatal testing and serial growth ultrasounds are generally indicated. If delivery is anticipated prematurely, antenatal steroids are also recommended.
In general, breastfeeding is contraindicated in women receiving chemotherapy or hormonal therapy because there is no short-term or long-term safety data. An exception to this guidance is azathioprine, which has failed to show accumulation in milk.
A large proportion of women diagnosed with cancer are less than 40 years of age with future reproductive goals. Subsequent pregnancy rates are 40% lower among cancer survivors compared to the general population, although these rates are dependent on type of cancer, with survivors of breast cancer having the lowest rates of successful pregnancy. Breast cancer survivors who do become pregnant have no difference in neonatal outcomes when compared to the general population. There is no defined timeline for when patients may attempt pregnancy after treatment. However, some specialists recommend a 2-year disease-free period because that is the highest window for recurrence.
Prior to women starting cancer treatment, the American Society of Clinical Oncology recommends that physicians address future fertility options and outcomes and provide prompt referrals to reproductive specialists. Fertility-sparing techniques include oocyte/embryo banking, ovarian tissue cryopreservation, ovarian suppression with gonadotropin-releasing hormone agonists, fertility preserving surgery, and ovarian transposition.