Aside from insomnia, restless legs syndrome (RLS) may be the most common sleep problem that occurs during pregnancy. For some women, it is their first experience of the condition. What are the symptoms of RLS in pregnancy? What causes RLS in pregnant women? Learn about the effects of RLS on sleep in pregnancy as well as the available treatments for the condition.
The Symptoms of RLS in Pregnancy
Restless legs syndrome is defined as an uncomfortable feeling occurring in the legs when lying down at night that provokes movement that relieves the feeling. Some women describe the feeling as bugs crawling under the skin, electrical sensations, or tightness in the legs. The feeling is disagreeable or uncomfortable and is accompanied by an irresistible desire to move. It is improved with movement, stretching, or rubbing of the legs. RLS can also affect the arms. It may also be called Willis-Ekbom disease.
The prevalence of RLS is estimated to range from 3% to 30% of pregnant women, making it two to three times as common as in the general population. The incidence and severity of restless legs syndrome is also strongly related to the progression of the pregnancy. It is most often a problem during the third trimester (especially the seventh and eighth months of pregnancy).
What Causes RLS in Pregnant Women?
There are a handful of recognized causes of RLS. If it occurs without another cause, it is called primary RLS. This may account for about 10% of women who have the condition even before they become pregnant. Secondary RLS may be due to various causes including iron deficiency, obesity, or kidney disease.
The association between RLS and pregnancy is not fully understood. It may relate to low levels of iron or folate before conception. As pregnancy advances, levels of hemoglobin, ferritin, and vitamin B12 naturally decline (even with supplementation). This may have a role. There are also important hormonal changes. Even sleep deprivation and anxiety might contribute.
There are some factors that are more often associated with RLS. For example, it is more common in pregnant women who are older, overweight or obese, smoke, or have sleep-disordered breathing (like sleep apnea). Some women have a family history. If it occurred in an earlier pregnancy, it is likely to recur. It also seems to be associated with movements of the legs during sleep, a condition called periodic limb movements of sleep (PLMS).
The movements of PLMS consist of periodic rhythmic extension of the big toe and drawing up of the foot at the ankle. Sometimes the knee or hip may also flex as part of the movement. About 80% of people with RLS also have PLMS.
The Effects of RLS in Pregnancy on Sleep
RLS can have important effects on sleep in pregnant women. Studies have shown changes in sleep patterns as well as increased sleep-related complaints.
Overnight sleep studies called polysomnograms demonstrate that women with RLS have less total sleep. It takes these affected women longer to fall asleep. In addition, they wake more frequently from sleep and suffer from insomnia. They are even more likely to snore or eat at night. As a result, there is an increased incidence of excessive daytime sleepiness.
Diagnosis and Treatment of Pregnancy-Related RLS
If you are experiencing the symptoms of RLS during pregnancy, you should speak with your doctor. Your doctor will evaluate if you have another condition that may be contributing to your symptoms. Some of the most important considerations include diabetes, thyroid disease, and kidney disease. RLS must be distinguished from leg cramps, vascular problems, neuropathy, and anxiety. It may be necessary to do some blood tests to check your ferritin, iron-binding capacity, folate, and B12 level.
Vitamin and mineral deficiencies that are identified will prompt recommendations for replacement. If your ferritin is <50 ng/mL, you should take iron replacement. Your doctor may recommend the use of folate and iron supplements, especially during the second and third trimesters. If necessary, a vitamin B12 injection may be given.
Further treatment may rely on lifestyle changes or physical interventions. It can be helpful to engage in gentle exercise such as walking or stretching before bed. The leg muscles may respond to massage or the use of cold or hot compresses. Some women will relaxation to be helpful. Distraction that involves increased mental activity may also offer relief, such as doing crossword puzzles.
Beyond these treatments, it can also be important to avoid triggers of restless legs. These might include the use of caffeine, alcohol, and nicotine. Certain medications such as dopamine antagonists (often used to treat psychiatric conditions), selective serotonin reuptake inhibitors (SSRIs), and antihistamines should also be avoided. Women with restless legs syndrome should follow guidelines to improve sleep. It can also be helpful to maintain a healthy weight.
It is sometimes necessary to use medications to relieve severe RLS symptoms. These should only be taken during the third trimester and at the lowest dose possible. This is important to prevent possible side effects in the fetus. Effective prescription medications may include opioids and dopaminergic medicines such as ropinirole or pramipexole. Magnesium may also be used and can be given intravenously in severe cases.
If you suffer from restless legs syndrome during pregnancy, you should start by speaking with your doctor. After a careful discussion, you can determine what measures to take to provide relief. Keep in mind that, if necessary, there are medications available late in pregnancy that can reduce your symptoms.
Kryger, MH et al. "Principles and Practice of Sleep Medicine." ExpertConsult, 5th edition, 2011, pp. 1579-1580.