Pregnancy: Inhibition of prostaglandin synthesis may adversely affect the pregnancy and/or the embryo/fetal development. Data from epidemiological studies raise concern about an increased risk of miscarriage and of malformations after the use of a prostaglandin synthesis inhibitor in early pregnancy. The risk is believed to increase with dose and duration of therapy. Available data do not support any association between intake of Aspirin and an increased risk for miscarriage. For Aspirin the available epidemiological data regarding malformation are not consistent, but an increased risk of gastroschisis could not be excluded. A prospective study with exposure in early pregnancy (1st-4th month) of about 14,800 mother-child pairs has not yielded any association with an elevated rate of malformations.
Animal studies have shown reproductive toxicity.
During the first and second trimester of pregnancy, acetyl salicylic acid containing drugs should not be given unless clearly necessary. If acetyl salicylic acid containing drugs are used by a woman attempting to conceive, or during the first and second trimester of pregnancy, the dose should be kept as low and duration of treatment as short as possible.
During the third trimester of pregnancy, all prostaglandin synthesis inhibitors may expose the fetus to: cardiopulmonary toxicity (with premature closure of the ductus arteriosus and pulmonary hypertension); renal dysfunction, which may progress to renal failure with oligo-hydroamniosis; the mother and the child, at the end of pregnancy, to: possible prolongation of bleeding time, an anti-aggregating effect which may occur even after very low doses; inhibition of uterine contractions resulting in delayed or prolonged labour.
Consequently, Aspirin is contraindicated during the third trimester of pregnancy.
Lactation: Salicylates and its metabolites pass into breast milk in small quantities.
Since no adverse effects on the infant have been observed so far after occasional use, interruption of breast-feeding is usually unnecessary.
However, on regular use or on intake of high doses, breast feeding should be discontinued early.