Restless legs is one of the few pregnancy symptoms that is genuinely difficult to describe to someone who has not had it, which is part of why it gets under-reported. It is not pain, it is not cramp, and it is not anxiety — it is a compulsion to move, and it arrives at exactly the moment you need to lie still.
The short answer: an urge to move the legs, worse at rest, worse in the evening, and relieved by moving. Substantially more common in pregnancy, particularly in the third trimester, and it usually resolves within days to weeks of birth. The most useful thing to do is ask for a ferritin test, not just a full blood count — low iron stores are the main treatable driver, and haemoglobin can be normal while ferritin is not. Most restless-legs medicines are avoided in pregnancy.
How it is recognised
Four features are used to identify it, and all four have to be present:
- An urge to move the legs, usually with an uncomfortable sensation — crawling, fizzing, pulling, an itch that is not on the skin.
- Worse at rest — sitting still in the evening, or lying down.
- Relieved by movement, at least while you keep moving.
- Worse in the evening or at night than during the day.
If moving does not relieve it, or it is equally bad at ten in the morning, it is probably something else — which is worth knowing, because the answers are different.
What is normal
| Restless legs | Something else | |
|---|---|---|
| Sensation | Urge to move, crawling or fizzing | Sharp painful contraction — that is a cramp |
| Movement | Relieves it | Makes it worse — think joint or vascular |
| Timing | Evening and night | Constant through the day |
| Sides | Both legs, sometimes alternating | One leg only, with swelling, warmth or redness — possible clot, ring today |
| Nerve signs | None | Numbness, weakness, shooting pain down the leg — see sciatica |
The iron question
This is the part worth taking to an appointment. Restless legs is associated with low iron availability in the brain, and that correlates with serum ferritin — the measure of iron stores — rather than with haemoglobin, which measures the iron currently in circulation. It is entirely possible to be told your blood count is normal while your stores are depleted.
So the request is specific: "I have restless legs at night. Could I have my ferritin checked, and could you tell me the number?" If it is low, treating it with iron improves the symptom for many people, and it treats something worth treating in its own right before birth.
Do not start an iron supplement on your own because you read this. Too much iron is not harmless, the dose matters, and the point of the test is to find out whether it is the answer. If iron is prescribed and it upsets your stomach, ask about alternate-day dosing rather than stopping — see the constipation page.
Ring the same day if the symptom is in one leg only and comes with swelling, warmth, redness or tenderness in the calf — that is assessed as a possible clot rather than as restless legs. Raise it at your next appointment if it is preventing sleep most nights, if you are exhausted to the point of being unsafe, or if you have low mood alongside it.
Restless legs in pregnancy — at a glance
Restless legs is defined by four features together: an urge to move the legs with an uncomfortable crawling or fizzing sensation, worse at rest, worse in the evening or night, and relieved by movement. It is considerably more common in pregnancy than outside it, peaks in the third trimester, and usually resolves within days to weeks of birth. The main treatable driver is iron status, and the relevant measure is serum ferritin rather than haemoglobin — iron stores can be depleted while the blood count reads normal, so the request to make is for ferritin specifically and for the actual number. Iron should not be started independently, since dose matters and the test is the point. Movement is the only reliable relief during an episode; regular earlier-in-the-day exercise, consistent bedtimes, less caffeine, a warm bath and leg massage help preventively. Most medicines used for restless legs outside pregnancy are avoided in it. One-sided symptoms with calf swelling, warmth or redness are assessed as a possible clot instead.
Inside Baby Novum: symptoms are logged against sleep in the daily check-in, so the ferritin request arrives supported by weeks of nights rather than by one bad one — which is the difference between a test being ordered and the symptom being noted. Encrypted on the device, no account, no server copy.
Frequently Asked Questions
What does restless legs syndrome feel like?
An urge to move the legs, usually with an unpleasant sensation described as crawling, fizzing, pulling or an itch inside the bone rather than as pain. Four features define it: the urge is worse at rest, worse in the evening or night, relieved by movement, and not explained by something else. It is not a cramp — a cramp is a painful contraction, this is a compulsion.
Why does pregnancy cause restless legs?
It is substantially more common in pregnancy than outside it, particularly in the third trimester, and it usually resolves within days to weeks of birth. The strongest modifiable association is iron status — specifically low brain iron, which correlates with low ferritin even when haemoglobin is normal. Folate status and the hormonal changes of pregnancy are also implicated.
Which blood test should I ask for?
Ferritin, not just a full blood count. A normal haemoglobin does not exclude depleted iron stores, and it is the stores that matter here — which is why someone can be told their blood count is fine and still have iron-responsive restless legs. Ask for ferritin specifically and ask what the number is rather than whether it is "normal".
What can I do about it at night?
Movement is the only thing that reliably relieves an episode — walk, stretch the calves, flex and point the feet. Preventively: regular gentle exercise earlier in the day, a consistent bedtime, cutting caffeine, a warm bath or leg massage before bed, and avoiding long periods sitting still in the evening. Taking prescribed iron improves it in many people whose ferritin is low.
Are restless legs medications safe in pregnancy?
The medicines usually used for restless legs outside pregnancy are generally avoided in it, which is why the iron question matters so much — it is the treatable lever that is actually available. Do not take a supplement or a sleep aid on your own initiative; ask your midwife or GP, and raise it if the symptom is preventing sleep, because severe cases are managed differently.