Baclofen is not considered safe during pregnancy. The FDA labeling states it “may cause fetal harm” based on animal data, and there are no well-controlled human studies confirming its safety. Animal studies in rats found structural birth defects at high doses, and a human comparison study of 134 pregnant women who took baclofen in early pregnancy showed an increased risk of major malformations compared to controls. That said, stopping baclofen abruptly carries its own serious risks, so the decision involves weighing real harms on both sides.
What Animal and Human Studies Show
In rat studies, baclofen given orally caused omphalocele (a defect where abdominal organs protrude through the belly wall), microcephaly, and vertebral arch widening that may indicate spina bifida. These occurred at doses roughly 13 times the maximum recommended human dose by body weight, and at levels that also caused the mother rats to eat less and gain less weight. Mice and rabbits did not develop the same abdominal defect, which makes the picture less clear, but incomplete bone development was seen in both rat and rabbit fetuses at high doses.
Human data is limited. One study published in Prescrire International compared 134 women who took baclofen in early pregnancy against 400 pregnant controls and found a higher rate of major malformations in the baclofen group. No large-scale studies have been done. The FDA label notes that the background risk of major birth defects in the general U.S. population is 2 to 4 percent, but does not specify how much baclofen raises that number because the data simply isn’t robust enough.
Neonatal Withdrawal After Delivery
One of the more concrete risks involves the baby after birth. Baclofen crosses the placenta, and infants born to mothers who took it throughout pregnancy can develop withdrawal symptoms within hours to days of delivery. Reported symptoms include increased muscle tone, tremor, jitteriness, and seizures. In one published case, a 7-day-old girl developed generalized convulsions after in utero baclofen exposure, with the mother having noticed abnormal movements starting on the baby’s second day of life.
The FDA recommends that if baclofen must be continued during pregnancy, the dose should be gradually reduced and the drug discontinued before delivery when possible. If tapering isn’t feasible, parents and caregivers should be warned so the newborn can be monitored for withdrawal signs.
Risks of Stopping Baclofen Abruptly
The complication on the other side of this equation is baclofen withdrawal in the mother. Abruptly stopping baclofen, or even reducing the dose too quickly, can trigger a withdrawal syndrome that ranges from uncomfortable to life-threatening. Early symptoms include a return of severe spasticity, fever, nausea, weakness, and unstable blood pressure or heart rate. Without treatment, these can progress to hallucinations, delirium, seizures, and dangerous muscle rigidity.
For women on oral baclofen, withdrawal is more commonly mild. For those with an intrathecal baclofen pump (where the drug is delivered directly into the spinal fluid), sudden interruption is far more dangerous and can lead to organ failure, cardiac arrest, and death within one to three days. Pump malfunctions, catheter problems, or infections that require pump removal create this risk. Any plan to reduce or stop baclofen during pregnancy needs to involve a slow, supervised taper rather than an abrupt stop.
Intrathecal Pumps vs. Oral Baclofen
How baclofen is delivered matters. Intrathecal pumps use micrograms of the drug rather than the milligrams involved in oral dosing. This dramatically lowers the amount circulating through the rest of the body, which likely reduces fetal exposure. In one published case series of three consecutive pregnancies in a woman with cerebral palsy using an intrathecal pump, none of the newborns showed withdrawal symptoms after delivery. By contrast, every reported case of neonatal baclofen withdrawal has involved oral baclofen use by the mother.
There are no controlled studies directly comparing the two delivery methods during pregnancy, so the evidence is limited to case reports. Still, the pattern suggests that intrathecal delivery may pose less risk to the baby, though the maternal withdrawal risk from pump failure is more severe.
What About Breastfeeding
Baclofen does pass into breast milk. Based on available data, a fully breastfed infant would receive roughly 0.048 mg per kilogram per day, which works out to about 3.6 percent of the mother’s weight-adjusted dose. This is below the 10 percent threshold that pharmacologists generally use as a cutoff for concern during breastfeeding, which is why some sources consider it relatively low risk for nursing mothers. However, this should still be discussed in the context of the individual situation and dose.
Alternatives During Pregnancy
There is no universally accepted muscle relaxant that’s clearly safe during pregnancy, which makes managing spasticity during this time genuinely difficult. In at least one documented case involving a pregnant patient with a neurological condition, specialists recommended avoiding all oral spasticity medications entirely. Instead, they used an epidural for acute muscle tone control during labor, along with positioning techniques (keeping limbs supported against gravity) and addressing the underlying triggers for spasticity flare-ups.
For women who depend on baclofen to manage conditions like cerebral palsy, multiple sclerosis, or spinal cord injuries, the practical reality is that some level of risk may need to be accepted. The goal is typically to use the lowest effective dose, taper before delivery if possible, and ensure the medical team is prepared to monitor the newborn for withdrawal. This is a decision that depends heavily on how severe the spasticity is, what dose is being used, and whether the drug is oral or intrathecal.