Naproxen is a commonly-used painkiller that is part of the family of medications known as non-steroidal anti-inflammatory drugs (NSAIDs). These drugs work by decreasing the activity of proteins known as enzymes that are involved in the inflammatory response. Like many medications, there are concerns with taking naproxen in pregnancy. This medication can at times be used safely during pregnancy, but there are limitations that are essential to ensure the health of the mother and baby.
Potentially, using naproxen in pregnancy can cause harm to the fetus. For this reason, medical professionals recommend that this medication should not be used in the last trimester of pregnancy, including during labor. This drug can pass into breast milk as well, so mothers that breast-feed their child should not take naproxen during this time.
Even in healthy individuals, this medication can pose a significant risk to the heart and cardiovascular system. This risk posed by naproxen in pregnancy may be intensified, as shown in some clinical research. In one study, a mother that had been taking 250 milligrams (mg) of this medication for premature labor at 30 weeks gave birth to twins, who both showed signs of distress at birth.
Drug levels were measured in the infants, and were found to be at dangerous levels. Both infants were suffering from pulmonary hypertension, and one passed away shortly after birth. It was concluded that the naproxen had inhibited the creation of certain proteins in the infants, and, in conjunction with the stress of birth, caused a hypertensive crisis.
Animal studies have revealed other dangers of taking naproxen in pregnancy. Lowered body weight at birth, a higher rate of fetal death, and an elevated rate of fetal abnormalities have all been linked to this medication. These abnormalities varied widely on a case-by-case basis, but included several deformities with fatal or lifelong consequences, such as fused vertebrae, heart defects, and missing lobes within the lungs. Problems with the formation of various bones were also linked to using naproxen in pregnancy.
Human studies have not been performed as to abnormality or death rates, but research indicates that taking naproxen can make labor times longer. For this reason, it should usually be avoided during the third trimester of pregnancy. Earlier during pregnancy, it should usually only be used if there are no alternative medications available and a minimal risk can be established.