Some studies have suggested that breastfeeding might offer women with multiple sclerosis a way to prevent symptom flare-ups after childbirth. But new findings refute that idea, researchers reported Wednesday.
In a study of nearly 300 pregnant women with MS, Italian researchers found no evidence that breastfeeding lowered a woman's odds of having worsening symptoms in the months after giving birth.
The study, experts say, means that women with MS should not make breastfeeding decisions based on the hope it will prevent symptom flare-ups, also known as relapses.
In fact, breastfeeding could increase the risk of worsening symptoms, since breastfeeding mothers are advised against taking the so-called disease-modifying drugs used to control MS.
Researchers suggest that nursing mothers avoid these drugs, which include brand-names like Avonex, Betaseron and Rebif - because it's possible they're passed to the baby through breast milk.
"It appears, based on the best available evidence, that the decision to breastfeed or not should not be based on the idea that breastfeeding is somehow protective against relapses," said Dr. Nicholas LaRocca of the National Multiple Sclerosis Society, who was not involved in the study.
Some small studies had suggested that women who breastfeed have fewer MS relapses than those who bottle-feed.
However, LaRocca said in an interview, those studies were subject to a key bias: Women who suffer symptom flare-ups right before they become pregnant, or during pregnancy, are also at increased risk of post-pregnancy relapses, so they may choose not to breastfeed so that they can go back on their MS medication. (The disease-modifying drugs are not approved for use during pregnancy, either.)
In that case, breastfeeding would only appear to have a protective effect against relapses.
MS is a nervous system disorder thought to arise when a person's immune system mistakenly attacks the body's own nerve fibers. MS leads to symptoms like muscle weakness, numbness, vision problems and difficulty with coordination and balance; in most cases, those symptoms come and go, worsening for a period of time, followed by a period of milder symptoms, or none at all.
Years ago, women with MS were advised to avoid pregnancy, partly out of concern that it could make their disease worse.
But studies in recent decades have shown that the opposite is true; many women see their symptoms improve or even disappear during pregnancy, possibly because immune system activity naturally declines and levels of anti-inflammatory hormones called corticosteroids naturally rise during pregnancy.
On the other hand, women commonly have symptom relapses in the months after giving birth. It's estimated that 20 percent to 40 percent of women have a flare-up in the first six months after delivery.
Some small studies have linked breastfeeding to a lower risk of those post-pregnancy relapses. Others have found no such connection. This latest study, reported in the journal Neurology, is in line with those.
Of 298 women researchers followed, 37 percent had a symptom relapse in the year after giving birth. Just under seven percent had two or more relapses.
There was no evidence that women who breastfed had a lower risk. Instead, the only factor that seemed to predict post-pregnancy relapse was a woman's symptom history: if she'd had a relatively higher number of relapses in the year before pregnancy, or during pregnancy, her risk of post-childbirth relapse was higher.
"Our findings actually suggest that the choice to breastfeed can be biased by disease activity before and during pregnancy," lead researcher Dr. Emilio Portaccio, of the University of Florence, told Reuters Health in an email.
He said that women with MS should be aware that symptoms may flare up after childbirth, and that the risk is even greater if they have had relapses in the year before or during pregnancy.
"In such a patient, breastfeeding may not be feasible and early post-partum treatment should be an option," Portaccio said.
In general, breast milk is considered the best nutrition for infants, and experts recommend that mothers try to breastfeed exclusively for their baby's first six months.
LaRocca said that, like any new mother, women with MS have to weigh the benefits of breastfeeding against any potential downsides, but with the added question of how their disease might be affected.
Unfortunately, there is no way to predict which women will have a relapse after giving birth. Even if a woman has been symptom-free before and during pregnancy, that's no guarantee against a post-pregnancy flare-up.
"MS is nothing if not unpredictable," LaRocca said. "(Breastfeeding) is a tough decision because of that unpredictability."
He suggested that each woman discuss the pros and cons with her own doctor.
Portaccio agreed. "The final decision on 'breastfeeding dilemma' is up to the patient," he said. "In my opinion, it is of crucial importance that the decision is made after receiving and understanding all information on possible drawbacks."
Portaccio and his co-researchers on the study have received research funding or have other financial connections to several manufacturers of MS drugs.