Restless Legs Syndrome
Restless Legs Syndrome (RLS) is a condition categorized by an irresistible urge to move the legs, especially when trying to fall asleep; it could be accompanied by other symptoms such as aching or tingling.
RLS is highly prevalent during pregnancy, but the exact mechanisms for why pregnancy causes this condition are not known. However, there are several theories, to include blood flow in the lower half of the body, as well as uterine weight potentially compressing nerves and further reducing blood flow.
Although RLS itself is not believed to cause complications, it may indirectly cause a significant lack of sleep in some women; a lack of sleep during pregnancy carries its own list of potential complications.
There are no evidence-based treatments for RLS during pregnancy, but various lifestyle methods may provide some relief enough to help women sleep. Depending on severity, medications may also be available, but there is limited to no safety data regarding these medications during pregnancy.
Women should inform their HCP if they believe they are experiencing this condition. HCPs can help women manage their symptoms and rule out any other possible cause for RLS.
Background
Restless Legs Syndrome (RLS), more recently renamed Willis-Ekbom disease, is a condition defined by unpleasant leg sensations accompanied by an irresistible urge to move the legs. Despite its high prevalence, the condition itself is understudied – especially during pregnancy.
RLS is considered a sensorimotor disorder; the sensory component is the urge to move the legs, and the motor component – moving the legs – relieves the urge. This urge can be so strong that some researchers have described it as “torture".
Other symptoms of the condition include pain, restlessness, tingling, burning, aching, or a “creeping” feeling, all of which mostly occur just prior to sleep; symptoms may increase the longer the legs are sedentary.
The prevalence of RLS is estimated at 5% to 15% in the general population, occurring equally in men and women. However, during pregnancy, this more than doubles to an estimated 12% to 34%.
Two separate studies (November 2020, February 2021) identified that almost one in five women had newly developed RLS at some point during pregnancy, with peak incidence in the second and third trimesters.
Causes
Interestingly, a number of studies indicate pregnancy itself is a cause of RLS, but the mechanism for how or why this occurs is not known.
Pregnancy could unmask certain vulnerabilities that predispose women to RLS such as a strong family history, low iron, folate, and/or vitamin D levels, hormonal changes, weight gain, and venous insufficiency (blood collecting in the veins). It is also possible the growing weight of the uterus puts a strain on the lumbosacral nerve roots, causing the unpleasant leg sensations – especially since symptoms resolve after delivery.
RLS symptoms also appear to worsen as pregnancy progresses, with the prevalence and severity being greatest in the third trimester, adding further evidence to the nerve compression theory.
The role of iron and/or folate (which are both involved in the formation of red blood cells) as risk factors for RLS in pregnancy is inconsistent and may lead to unnecessary supplementation. Several studies indicate that since RLS resolves quickly after delivery, that iron/folate cannot be responsible as it takes more time for these levels to go back to normal.
Hormones are thought to be involved mostly due to the fast relief of symptoms upon delivery, when hormones levels return to normal levels; however, if hormones are a significant factor in RLS development, it is hypothesized the prevalence of RLS should then be much higher.
A study published in October 2020 determined there may be a link between antacid medications and RLS. Although the study was not pregnancy-specific, antacid medications and RLS are both common in pregnancy. It is possible these results could be extrapolated to pregnant women, but more research is necessary, as RLS could be caused by different mechanisms during pregnancy.
The study authors determined that evidence of these drugs contributing to RLS risk could suggest a need to re-evaluate the use of antacids in those at higher risk for developing the condition. (Women should always talk to their provider before stopping or starting any medication, even over-the-counter).
Additionally, there are psychological conditions that may contribute to, and exacerbate RLS symptoms, including anxiety, stress, tension, and insomnia.
Other conditions that occur during pregnancy can mimic or be misdiagnosed as RLS such as nocturnal leg cramps and hypnic (hypnagogic) jerks.
Hypnic jerks are involuntary twitches that occur just as a person starts to fall asleep, causing the individual to startle awake. Unlike RLS, hypnic jerks are not associated with leg sensations or an urge to move them.
Leg cramps are defined as painful, involuntary contractions of the muscles in the legs or feet that most often occur at night and during pregnancy.
Complications
Almost all complications associated with RLS are related to a lack of sleep, which is a direct result of the condition. Further, the more severe the condition, the less sleep obtained, and a significant lack of sleep can also worsen RLS, resulting in a perpetual cycle.
Poor sleep has its own set of complications during pregnancy, therefore RLS can indirectly lead to these same complications. Researchers have recognized this and have advocated for additional research into the condition.
RLS has also been independently associated with growth problems in the fetus, preterm labor, preeclampsia, and cesarean section, but the mechanisms for how this occurs are not clear. Further, RLS during pregnancy is a risk factor for developing a chronic "idiopathic" form of RLS in the future.
Management
RLS symptoms usually improve during the first four weeks postpartum; however, early detection, management, and treatment are necessary to prevent complications that can result from severe RLS during pregnancy.
As there are no evidence-based accepted guidelines for the treatment of RLS during pregnancy, all proposed therapies should include a risks and benefits approach.
Additional management should first begin with lifestyle modifications to avoid medications if possible (see Action section).
Standard medications for treating RLS during pregnancy have not been established, and medications used for RLS in the non-pregnant population have not been studied during pregnancy and have, overall, very little to no safety data. These drugs include dopaminergic agents (first line), benzodiazepines, opioids, and anti-epileptic agents.
Action
Women should tell their HCP if they are experiencing symptoms that may indicate RLS. HCPs can perform a physical assessment and help women cope with their symptoms and possible lack of sleep. HCPs will also want to rule out any other possible causes for these same symptoms.
Moderate aerobic exercise can help improve symptoms of RLS, but women should avoid heavy/intense exercise, especially late at night which could worsen symptoms.
Although evidence regarding massage and/or compression therapy for RLS is limited, these methods are unlikely to make the condition worse. Further, they could improve other leg symptoms/conditions of pregnancy, to include swelling, venous insufficiency, venous thromboembolism, and discomfort associated with varicose veins.
Women should also consider sharing and submitting their experience below regarding RLS during pregnancy. This can help other women learn potential ways to manage their symptoms and help them obtain better sleep.
Resources
Restless Legs Syndrome Fact Sheet (National Institute of Neurological Disorders and Stroke)
Restless Legs Syndrome Foundation: "The Restless Legs Syndrome Foundation is the leading organization for science-based education and patient services for people suffering from restless legs syndrome."