Use of non-steroidal anti-inflammatory drugs in pregnancy: impact on the fetus and newborn

Non-steroidal anti-inflammatory drugs (NSAIDs) are commonly prescribed in pregnancy to treat fever, pain and inflammation. Indications for chronic use of these agents during pregnancy are inflammatory bowel or chronic rheumatic diseases. Since the seventies, NSAIDs have been used as effective tocolytic agents: indomethacin has been the reference drug, delaying delivery for at least 48 hours and up to 7-10 days. Additionally, self-medication with NSAIDs is practiced by pregnant women. NSAIDs given to pregnant women cross the placenta and may cause embryo-fetal and neonatal adverse effects, depending on the type of agent, the dose and duration of therapy, the period of gestation, and the time elapsed between maternal NSAID administration and delivery. These effects derive from the action mechanisms of NSAIDs (mainly inhibition of prostanoid activity) and from the physiological changes in drug pharmacokinetics occurring during pregnancy. Increased risks of miscarriage and malformations are associated with NSAID use in early pregnancy. Conversely, exposure to NSAIDs after 30 weeks' gestation is associated with an increased risk of premature closure of the fetal ductus arteriosus and oligohydramnios. Fetal and neonatal adverse effects affecting the brain, kidney, lung, skeleton, gastrointestinal tract and cardiovascular system have also been reported after prenatal exposure to NSAIDs. NSAIDs should be given in pregnancy only if the maternal benefits outweigh the potential fetal risks, at the lowest effective dose and for the shortest duration possible. This article discusses in detail the placental transfer and metabolism of NSAIDs, and the adverse impact of prenatal NSAID exposure on the offspring.