The More, the Merrier… Down the Road? - EMBARGOED 7-Mar-2012 16:00 ET

Multiple pregnancies linked to decreased risk of developing multiple sclerosis

(RxWiki News) Having many children may wear you out, but some unexpected health benefits have been linked to having multiple pregnancies - a lower risk of developing multiple sclerosis.

A recent study has found that women's risk of getting multiple sclerosis, or MS, drops as the number of pregnancies they have had increases.

"See your doctor if you experience unexplained muscle tingling, numbness or weakness."

While these findings don't necessarily mean that having more children will prevent women from developing MS, the apparent association between them might help explain higher rates of MS, according to lead author Anne-Louise Ponsonby, Ph.D., of Murdoch Children's Research Institute in Melbourne, Australia.

"In our study, the risk went down with each pregnancy and the benefit was permanent," Ponsonby said.

Ponsonby and her colleagues reviewed data on 282 men and women diagnosed with central nervous demyelination. This diagnosis means they are experiencing their first MS-type symptoms but that they have not yet been diagnosed with MS.

The participants ranged in age from 18 to 59 years old, and their data was compared to that of 542 men and women with no MS symptoms. Researchers took note of how many children the men had and how many live births and pregnancies (of at least 20 weeks) the women had.

Although no link was found between men who developed MS symptoms and the number of children they had, researchers did find a correlation between the number of pregnancies the women had and their likelihood of developing MS symptoms.

Those with at least two pregnancies were a quarter as likely to develop symptoms of the condition compared to women who had never been pregnant. Women with five or more previous pregnancies only had about 5 percent of the risk that never-pregnant women had.

"The rate of MS cases has been increasing in women over the last few decades, and our research suggests that this may be due to mothers having children later in life and having fewer children than they have in past years," said Ponsonby.

Multiple sclerosis is a chronic disease of the nervous system that affects the brain, spinal cord and nerves. Symptoms range from mild to severe and include numb, tingling or weak muscles, blurred or double vision and difficulty with balance. Currently, there is no known cure.

The study appeared online March 7 in the journal Neurology. The research was funded by the National Multiple Sclerosis Society of the U.S.A., the National Health and Medical Research Council of Australia and the Multiple Sclerosis Research Australia.

No information was available regarding potential conflicts of interest.

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Review Date: 
March 7, 2012