Restless legs syndrome (RLS) is a common physical and nervous system disorder. It is even more common during pregnancy. In fact, it may affect up to one in five pregnant women. 
RLS causes an intense and urgent need to move your legs. Although not painful, the urge is uncomfortable and is only relieved by movement. For many women RLS is just one more nuisance to deal with during pregnancy, but for some women, RLS can interfere with sleep and cause significant stress and exhaustion. 
RLS is two to three times more common in pregnant women than in the rest of the population.  If you have RLS before pregnancy, it is liable to get worse during pregnancy. For most women, RLS starts during pregnancy, usually during the last trimester. The good news is that RLS usually goes away after giving birth. 
What Causes RLS?
RLS is also called Willis-Ekbom disease. The cause is not known, but there are several theories with some studies to support them. Theories include low levels of iron and folic acid, changes in a chemical brain messenger called dopamine, and abnormal genes passed down through families. [1,2]
Iron and folic acid are needed to make dopamine. Low levels of dopamine are the cause of Parkinson’s disease, and RLS may be a disease that is similar to Parkinson’s disease. Having a family history of RLS greatly increases your risk for developing it, so genes are probably involved as well. 
Why Is RLS More Common in Pregnancy?
Pregnancy may trigger RLS in several ways. Theories include: 
- Low Iron or Folic Acid Levels, which are more common during pregnancy
- Changes in hormone levels caused by pregnancy, which may include estrogen, progesterone, prolactin, or thyroid hormones
- Stress, fatigue, and poor sleep due to pregnancy
- Pressure on nerves of the legs from belly growth or leg swelling due to water retention (edema)
Are You at Risk for RLS?
If you have already been diagnosed with RLS, you are at risk for your symptoms to become worse. Pregnancy is more likely to bring on your first symptoms of RLS, you may be at higher risk if: [1,2]
- You have a family history of RLS
- You had RLS during a past pregnancy
- You are anemic (have low red blood cells)
- You have had multiple pregnancies
- You have sleep apnea
- You do not get regular exercise
- You smoke or drink alcohol
- You drink lots of coffee
- You take medication for morning sickness
- You take an antihistamine
How Is RLS Diagnosed?
There are no tests that can diagnose RLS. The diagnosis is made from your symptoms. These are the symptoms needed to make the diagnosis: 
- You have a persistent and uncomfortable urge to move your legs
- Your symptoms get worse with rest and at night
- Your symptoms get better during the day and with movement
- Your symptoms are not caused by any other condition such as cramps, arthritis, or edema
What to Do if You Develop RLS?
There are medications that are approved to treat RLS, but these medications have not been shown to be safe during pregnancy or breastfeeding. Medications are rarely used during pregnancy or while breastfeeding. If they are used, they are a last resort. In the vast majority of cases, you can get through RLS with these steps: [1,2]
- Get lots of low-impact exercise. Exercise may be the best treatment for RLS.
- Take an afternoon nap. RLS tends to be better in the daytime. An afternoon nap may help you avoid fatigue caused by RLS symptoms at night.
- Do an activity that requires concentration when you have symptoms. Playing a game or doing a puzzle seems to help.
- Avoid alcohol and smoking. This should go without saying.
- Avoid caffeine. Caffeine makes RLS worse and pregnant women are more sensitive to caffeine.
- Avoid over-the-counter antihistamines and nausea medications.
If your doctor diagnoses RLS, he or she may check your iron levels. If your iron is low, you may be be given an iron supplement. You should already be on a multivitamin that includes folic acid. Your doctor may take you off medications that have been linked to RLS. These medications include antihistamines, anti-nausea medications, and antidepressants. The morning sickness medication ondansetron (Zofran) is not linked to RLS. [1,2]
As a last resort, medications with low pregnancy risk that may help RLS include dopamine replacement medications, antianxiety medications (benzodiazepines), and some types of anti-seizure medications. 
RLS is a common disorder of pregnancy. It can be an uncomfortable nuisance, especially during the third trimester. It is not dangerous for you or your baby, but it can interfere with sleep and add unwanted fatigue and stress. In most cases, RLS can be managed without medication. [1,2]
One final through, if you have RLS during pregnancy, even if it goes away after giving birth, it may come back. Recent studies show that women with RLS during pregnancy have a higher risk of developing RLS in the future. Hopefully, that will not be you. If it is, there are many effective medication options you will be able to try when you are not pregnant. [1,2]