During pregnancy the body holds on to more fluid and, as the uterus grows, it slows down the blood coming back up from the legs. That fluid settles low down, in the feet and the ankles.
It is eight in the evening, you slip your shoes off and the sock has left its mark right around your ankle. The shoe that went on without a second thought this morning now presses at the sides. And your ankle, which always had a bone right there, is smooth today.
It happens to a great many pregnant women, and there is an explanation for it. Let's look at why feet and ankles swell during pregnancy, when it tends to show up, what helps to ease it, and when it is worth having your midwife take a look.
Why do your feet swell during pregnancy?
Picture a garden hose stretched out across the lawn. The water runs fine until somebody leaves a plant pot on top of it. The pot doesn't close the hose, it just narrows it, so the water moves more slowly and builds up behind.
Something similar goes on inside your legs. The uterus keeps growing and presses on the veins that carry blood back from the legs to the heart, so that return journey slows down1,2. At the same time your body is handling more fluid than usual, because the hormonal changes of pregnancy encourage it to hold on to it1,2. Blood pools in the veins of the leg, part of the fluid seeps out into the surrounding tissue2, and that is exactly what you can see. The technical name is oedema2, which is no more than fluid gathered in the tissues.
It shows up mostly in the feet and the ankles for the same reason water will not climb a hose on its own: gravity. They are the lowest point of the whole system. In the leg it feels different, more like heaviness and tightness than a change of shape. So some days you describe it as swollen feet and other days as swollen legs in pregnancy, and both are the same mechanism seen from two places.
If you want the full picture of why legs swell, beyond pregnancy, we go through it in our post on swollen legs.
Is it normal for feet and ankles to swell?
Yes, and it is one of the most common things in pregnancy. Mild oedema in the feet, ankles and legs is common during the second half of pregnancy2, and it usually clears up a few weeks after the baby is born1.
What you would expect has a fairly recognisable shape: both feet swell, not just one1,2,3, and it gets worse towards the end of the day3. Anything that falls outside that picture is what deserves a phone call, and we cover it at the end of the post.
When in pregnancy does it show up?
Mostly in the third trimester. That is the stage when fluid gathers most easily2, and the swelling tends to increase as the due date gets closer3. So if you are 37 weeks along and looking at your ankles with a puzzled face, you fit the most common pattern exactly.
It can turn up earlier if you spend many hours on your feet, or if your pregnancy falls in the middle of summer1,3. And it can almost pass you by: there are pregnancies where it is barely noticeable.
How can you relieve swollen feet in pregnancy?
Let's be clear from the start that none of this makes the swelling disappear overnight, because the cause is still there until the baby arrives. What these things do achieve is that the fluid doesn't sit still down there for so many hours at a stretch.
Move a little, and often
Neither long spells on your feet nor long spells sitting down. Both held positions work against you, and the sources agree on avoiding standing for long periods1,3 and on keeping up some regular exercise3. A short walk after lunch, or getting up now and then if you work sitting down, already shifts the needle.
Sitting still in the same spot there is something you can do too: circle your ankles and gently flex your feet to stretch the calf1. If you spend hours in a chair, stretch often and don't cross your legs3.
And if you have a pool nearby, make the most of it. Standing or walking in the water compresses the tissues of the leg and can relieve some of the swelling1; swimming counts just the same3. There are more ideas in how to improve blood circulation in the legs.
Feet up
Resting often with your legs raised is one of the few things that works while you do nothing at all1,2. Lie down, put a couple of cushions under your calves so that your feet end up higher than your hips, and let gravity work in your favour for a while. Keeping your legs slightly raised on pillows while you sleep helps too1.
Sleep on your left side
This piece of advice sounds like a midwife's quirk and it has a very physical explanation. The large vein that returns blood from the lower half of the body to the heart, the inferior vena cava, runs down the right-hand side. When you lie on your left side, the uterus stops resting on top of it and the blood comes back more easily1,2. It is the plant pot from earlier, moved off the hose.
Drink water, however contradictory it sounds
Having swollen ankles does not mean you should drink less1. When the body senses it is dehydrated it tends to hold on to even more fluid3, so water is working for you. A common recommendation during pregnancy is around 2.3 litres of fluid a day1.
Clothing that doesn't grip in one spot
Tight elastic, especially at the ankle and the calf, makes it harder for blood to flow freely1. MSD spells it out: loose clothing that does not restrict the flow, and no socks or stockings with tight bands at the ankles or the calves2.
Hold on to that sentence for thirty seconds, because it has a bearing on what comes next.
Do light compression socks help?
Every piece of advice above has the same weak point: it depends on you remembering. And in the third trimester you sleep badly, you tire sooner, and there are afternoons when a walk is the last thing you fancy.
A graduated compression sock works away in the meantime. It presses a little more at the ankle and eases off towards the knee, following the same path the blood takes on its way back. Both Mayo Clinic and MSD list compression stockings among the things that help with the normal swelling of pregnancy1,2, and the moment to put them on is when you get up in the morning3, while the leg is still unswollen.
Here it is worth telling foot and leg apart once more. The compression works on the leg, from the ankle to the calf. The foot stays loose, whichever size you choose. That is why you work out the size by measuring the leg rather than by the shoe size you wear, which at this stage of pregnancy is a relief: you have it step by step in the size guide. And if bending over is already an extreme sport, how to put on compression socks has a couple of ways of doing it without folding yourself in half.
About the marks they leave, which is the question that always comes up: a light mark from the top edge when you take them off is perfectly normal, as with any sock. A deep mark, the sort that looks like a groove, usually means the size is not the right one. Calcetinos, what's more, have no tight elastic at the top, and that is a deliberate decision: precisely so as not to squeeze the leg or leave the kind of tight band the sources warn about2. The top part sitting a little loose is by design.
They are light graduated compression socks, with 14 to 17 mmHg tested in an external laboratory, OEKO-TEX Standard 100 certification, and made in Spain. If you want to know what that figure means, we explain it in what mmHg means in compression stockings. They are not a medical device and they are not dispensed on prescription. If your midwife or your doctor has prescribed a particular level of compression, that is the one to wear, and it is bought at the pharmacy. For light everyday compression, you are in the right place.
How to choose them, from when you can wear them and how many hours a day is all gathered in compression socks for pregnancy.
Every model has the same light graduated compression and the same length, ending just below the knee. What changes is the material.
Calcetinos for pregnancy
All three with light graduated compression, ending just below the knee. Choose the material to suit the moment.
Light graduated compression of 14 to 17 mmHg, made in Spain. They are not a medical device.
If you have sensitive skin, the Nature Bambú is the hypoallergenic one of the range and we talk about it in socks for sensitive skin. And if you are wondering how many hours at a stretch to wear them, you have it in how long to wear compression socks.
Why do feet swell more in summer?
Because the heat adds to everything above. Swelling in the feet and ankles gets worse towards the end of the day and when the weather is hot3, so a July pregnancy feels rather different from a February one.
Keeping cool on hot, humid days is part of the plan3: hours in the shade, water within reach, and the spell with your legs up somewhere cool in the house. For those months there is the summer collection, with Coolmax fabric, the most breathable of all the ones we use.
When should you speak to your midwife or doctor?
Mild swelling of the feet and ankles during pregnancy is not a cause for concern1. That said, there is a handful of signs the medical sources flag as worth a call without waiting for your next appointment:
- Swelling that comes on suddenly or increases quickly, in the feet or anywhere else in the body1,2,3.
- One leg or one calf swollen on its own, especially if that area is warm, red or sore1,2.
- Swelling in the face or around the eyes, or more than mild swelling in the hands, the sort where you cannot get a ring off2,3.
- A severe, persistent headache, changes in your vision, intense pain in the upper abdomen or difficulty breathing2.
Some of those signs can be related to pre-eclampsia, a condition that only appears during pregnancy and in which blood pressure and protein in the urine rise2. That is checked at the appointment, with a blood pressure cuff and a test, so whenever you are in doubt the answer is always the same: call and have it looked at.
And one thing worth being clear about. Light compression socks support the wellbeing of the leg and help make the day more bearable. They do not treat, cure or prevent anything on this list.
Frequently asked questions about swollen feet in pregnancy
When do feet swell during pregnancy?
Mostly in the third trimester, which is when fluid gathers most easily2, and it increases as the due date approaches3. Within the day, you would normally notice it more in the afternoon3, and more still in hot weather.
How can you bring down swollen feet in pregnancy?
What works best is the opposite of staying still in one position for a long time: spells with your legs raised1,2, short walks and gentle movement often1,3, sleeping on your left side1,2, and no clothes or socks that grip at the ankle or the calf1,2.
Is it normal to have just one swollen foot?
In pregnancy the usual thing is for both to swell. One leg or one calf swelling on its own, especially if it is warm, red or sore, is one of the signs worth checking as soon as possible1,2,3.
Can you wear compression stockings while pregnant?
Mayo Clinic and MSD list compression stockings among the measures that help with the normal swelling of pregnancy1,2, and the sensible thing is to put them on when you get up3. How to choose the size, the material and from when to wear them is in compression socks for pregnancy. If your midwife or your doctor has prescribed a particular level of compression, follow them.
Does the swelling go away after the birth?
Generally yes, a few weeks after the baby is born1. In the meantime, the same advice still applies.
Please note: this content is for information only and does not replace the assessment of a healthcare professional.
What you can do this very afternoon
Not much, and nothing complicated: a spell with your feet higher than your hips before dinner, sleeping on your left side, nothing gripping your ankle, and a pair of compression socks on since first thing, which are the only ones still working when you have already called it a day. You have them all together in compression socks.
It is weeks away, not years. And remember that not all compression socks are Calcetinos... or the same 😉
Sources
- Mayo Clinic. Ankle swelling during pregnancy: What helps? 21 March 2026. Available at: mayoclinic.org
- MSD Manual Consumer Version. Swelling During Late Pregnancy. Reviewed February 2026. Available at: msdmanuals.com
- Nemours KidsHealth. Dealing With Swollen Ankles During Pregnancy. Reviewed January 2021. Available at: kidshealth.org
