Tylenol (acetaminophen, or in Europe it is called paracetamol) is the go-to drug for pain, headaches, and fever during pregnancy. A new study just published in the journal JAMA Pediatrics indicates that this drug may not be as safe as previously thought.

Animal research has long suggested that acetaminophen is a so called hormone disruptor, a substance that changes the normal balance of hormones. It is a well-established fact that an abnormal hormonal exposures in pregnancy may influence fetal brain development.

Danish researchers decided to evaluate whether prenatal exposure to acetaminophen increases the risk for developing attention-deficit/hyperactivity disorder (ADHD) in children. They studied 64,322 live-born children and mothers enrolled in the Danish National Birth Cohort during 1996-2002.

The doctors used parental reports of behavioral problems in children 7 years of age using a specific questionnaire, retrieved diagnoses from the Danish National Hospital Registry or the Danish Psychiatric Central Registry, and identified ADHD prescriptions (mainly Ritalin) for children from the Danish Prescription Registry.

More than half of all mothers reported acetaminophen use while pregnant. Children whose mothers used acetaminophen during pregnancy were at about 1.3 times higher risk for receiving a hospital diagnosis of ADHD, use of ADHD medications, or having ADHD-like behaviors at age 7 years. Stronger associations were observed with use in more than 1 trimester during pregnancy and with higher frequency of intake of acetaminophen.

The researchers concluded that maternal acetaminophen use during pregnancy is associated with a higher risk for ADHD-like behaviors in children.

This presents a difficult problem in treating headaches and pain in pregnant women. Aspirin and other non-steroidal anti-inflammatory drugs such as ibuprofen and naproxen can cause other problems in pregnancy and are particularly dangerous in the third trimester. In women with migraines, acetaminophen tends to be ineffective anyway, so these women should be given migraine-specific drugs, such as triptans (Imitrex or sumatriptan, Maxalt or rizatriptan, and other). They are much more effective than acetaminophen and the woman may need to take much less of these drugs than of acetaminophen. Triptans are also in category C in pregnancy, which means that we do not know how safe they are. Imitrex was introduced more than 20 years ago and we do not that it does not have any major risks for the fetus, but that does not mean that more subtle problems, such as ADHD are also not more common. Another headache drug that should be avoided in pregnancy is Fioricet. It is popular with some obstetricians because it has been on the market for 40 years. However, it contains not only acetaminophen, but also caffeine, which can make headaches worse, as well as a barbiturate drug butalbital, which can also have deleterious effect on the fetal brain.

Fortunately, two out of three women stop having migraines during pregnancy, especially in the second and third trimester. If they continue having headaches, treatment is directed at prevention. Regular aerobic exercise, getting enough sleep, regular meals, good hydration, avoiding caffeine, learning biofeedback, meditation or another form of relaxation, magnesium supplementation, are all safe and can be very effective. Acute treatments that do not involve drugs are often not very practical for a busy person. However, if the headache prevents normal functioning anyway, taking a hot bath with an ice pack on the head at the same time can help some women. Taking a nap, getting a massage, aromatherapy with peppermint and lavender essential oils are good options. For nausea, ginger and Sea Bands are sometimes very effective.