Methotrexate Pregnancy and Breastfeeding Warnings
Methotrexate Pregnancy Warnings
Anecdotal data have revealed the following MTX-induced congenital defects: absence of labdoid and coronal sutures, oxycphaly, absence of frontal bone, low set ears, hypertelorism, dextroposition of the heart, absence of digits, growth retardation, wide posterior fontanel, hypoplastic mandible, multiple anomalous ribs, depressed/wide nasal bridge, and long webbed fingers. Based on several instances of congenital abnormalities among infants whose conceptions were dated up to 7 months after their mothers had received MTX, some experts theorize the drug may persist in maternal tissues for prolonged periods of time. Data have revealed an association between the use of chemotherapy combinations that contain MTX during pregnancy and neonatal myelosuppression (anectdotal data), low birth weight (40% of infants), and persistent congenital chromosomal abnormalities (limited data). Retrospective analysis of 436 female cancer survivors who received chemotherapy which included MTX (average duration of chemotherapy was 4 months), of whom 187 (43%) had at least one live birth (average interval between MTX use and conception was 2.7 years), has revealed no statistically significant association between the use of MTX and congenital defects. Observed congenital abnormalities included anencephaly (2), spina bifida (1), tetralogy of Fallot (1), talipes equinovaus (1), collapsed lung (1), umbilical hernia (1), desquamative fibrosing alveolitis (1), asymptomatic heart murmur (1), mental retardation (1), and sudden infant death syndrome (1, at 4 weeks of age). One study reported the results of four patients who had received low dose weekly pulses of MTX inadvertently taken from up to one to six weeks gestation. One patient miscarried at week six while the other pregnancies ended with the delivery of healthy children.
Methotrexate (MTX) has been assigned to pregnancy category X by the FDA. MTX can cause fetal death or teratogenic effects when administered to a pregnant woman. Women of childbearing potential should not be started on MTX until pregnancy is excluded and should be fully counseled on the serious risk to the fetus should they become pregnant during treatment. Pregnancy should be avoided if either partner is receiving MTX, during and for a minimum of 3 months after therapy for male patients, and during and for at least 1 ovulatory cycle for female patients. This drug has been successfully used to terminate tubal pregnancy. MTX is contraindicated in pregnant patients with psoriasis or rheumatoid arthritis and should be used in the treatment of neoplastic diseases only when the potential benefit outweighs the risk to the fetus.
Methotrexate Breastfeeding Warnings
Methotrexate (MTX) is excreted into human milk in low concentrations. Because of the potential for serious adverse reactions from MTX in breast-fed infants, it is contraindicated in nursing mothers. The American Academy of Pediatrics considers MTX to be contraindicated during breast-feeding because of several potential problems, including immune suppression, neutropenia, adverse effects on growth, and carcinogenesis.
MTX is excreted into human milk. In one case, peak milk MTX levels of 6 x 10-9 M, or 0.26 mcg/dL, were detected approximately 10 hours after dosing in a woman who was receiving 22.5 mg of MTX per day. The highest milk:plasma MTX ratio was 0.08:1. The cumulative excretion of MTX in milk within the first 12 hours after oral administration was 0.32 mcg. Although adverse effects were not reported in her nursing infant, and the milk MTX levels from this case represent nontoxic doses for infants, experts consider the use of MTX to be contraindicated during breast-feeding because of the unknown risk of this concentration of MTX to the nursing infant, the possibility of accumulation of the drug in neonatal tissues, and because of the known adverse effects of MTX in breast-fed infants.
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