Breastfeeding Appears Safe While Being Treated for Postpartum Relapse

The corticosteroid methylprednisolone is detected at low, safe levels in the breast milk of women with multiple sclerosis (MS) during and after intravenous (into-the-vein) treatment for a postpartum relapse, according to a small study in Turkey.

While these findings suggest that women can safely breastfeed their child during and shortly after a methylprednisolone infusion, the researchers recommended they wait two to four hours after treatment to further limit the baby’s exposure.

The study, “Methylprednisolone Concentrations in Breast Milk and Serum of Patients with Multiple Sclerosis Treated with IV Pulse Methylprednisolone,” was published in the journal Clinical Neurology and Neurosurgery.

Women with MS are at increased risk of a relapse after giving birth (postpartum period). High-dose intravenous methylprednisolone is used as a first-line treatment for acute relapses of MS, but data on its safety during breastfeeding remain limited.

A previous Turkish study in 16 women with MS suggested that the transfer of methylprednisolone into breast milk was very low, leading to a relative infant dose (RID) of 0.71%, well below the generally acceptable RID value of less than 10%. RID estimates an infant’s exposure to a medication via breast milk.

Now, researchers involved in that study set out to further analyze the association between methylprednisolone levels in blood and breast milk of women with MS during and after treatment administration.

The study included 12 breastfeeding women with MS (mean age, 28.03) being treated for postpartum relapse with a 1,000 mg methylprednisolone infusion (given over one hour) for three or five consecutive days.

These women had a mean disease duration of 3.59 years and minimal disability, as shown by a mean score of 1.5 on the expanded disability status scale — a method of quantifying disability in MS, with higher scores indicating greater disability.

Maternal blood and breast milk samples were obtained at the first day of treatment. Researchers collected the samples before therapy infusion, 30 minutes into the infusion, at the infusion’s end, and after one, two, four, eight, 12, and 24 hours (just before the second day’s infusion).

Babies were breastfed no less than two hours after methylprednisolone therapy. Four women were fully breastfeeding, and eight were combining breastfeeding with formula feeding.

The health and wellbeing of the infants (seven boys and five girls), with a mean age of 8 months, were evaluated by questioning the mother, and reviewing the developmental assessment and medical records of each child’s pediatrician or general physician.

A strong association was found between blood and breast milk methylprednisolone levels, with a similar trend seen at all time points. The highest methylprednisolone levels in blood (6.09 micrograms/ml) and breast milk (2.09  micrograms/ml) were detected at the end of the infusion, after which the levels dropped exponentially.

Therapy levels in blood and breast milk were almost half of the highest value at 30 minutes into the infusion, and dropped below 1 microgram/ml at four hours after treatment in breast milk, and at eight hours in blood.

Methylprednisolone levels were not detectable in breast milk at 12 and 24 hours after infusion, or before the infusion.

Based on these data, the team estimated that the infant dose of methylprednisolone was 0,0695 mg/kg/day, which was “significantly lower than the recommended dosage of 0.25–30 mg/kg/day prescribed for [newborns] who require methylprednisolone therapy,” the researchers wrote.

The estimated RID was also 20 times lower than the accepted concern level of 10%, with a value of 0.50%.

No adverse events were observed in infants over six to 24 months of follow-up. They were at a normal weight and height, and had reached motor milestones at expected times.

These findings suggest that a weak transfer exists of methylprednisolone into breast milk, with low levels of the therapy being detected during and after infusion, and resulting in infant doses below levels likely to cause harm.

Nevertheless, the researchers recommended that “mothers can choose to wait 2 to 4  hours to further limit the level of exposure” to the therapy.

Researchers also noted that future larger studies are needed to confirm these findings, and better understand the safety of intravenous methylprednisolone in the treatment of relapses in breastfeeding women with MS.