Check the temperature before you settle for "it's just pregnancy"

Feeling hot is ordinary in pregnancy. Feeling hot with a raised temperature is not, and the two feel similar from the inside, which is why this page starts here.

The NHS lists the signs of a high temperature as feeling hotter than usual, shivering (chills), or a thermometer reading of 38C or above, and says a high temperature can be a sign of an infection, so it is important to get it checked out.

Tommy's sets a lower trigger for pregnancy specifically: "Call your GP, midwife or hospital maternity unit if your temperature is above 37.5 degrees Celsius, even if you have no other flu or cold symptoms." It explains why it uses the lower number: "A high temperature is 38C or above. But even 37.5C could be a sign of a hidden infection."

So: a thermometer, bought at any pharmacy or supermarket, settles this question in thirty seconds. Below 37.5C with no other symptoms, read on. Above it, ring.

Why pregnancy runs hot

The NHS gives two mechanisms in one sentence: "You're likely to feel warmer than usual during pregnancy. This is due to hormonal changes and an increase in blood supply to the skin. You're also likely to sweat more."

That extra blood supply is the part people underestimate. Blood volume rises substantially through pregnancy, and a good deal of the extra flow goes to the skin, which is why your hands and face feel warm to other people and why you stop needing a jumper indoors. Sweating more is the body's way of shedding the heat, not a sign that anything is wrong.

Tommy's adds one calibration worth having: it is normal for your body temperature to rise in pregnancy, "but only by a fraction". Feeling markedly hot is common; measuring markedly hot is not.

What it looks like in practice

Flushes. Sudden waves of heat, often across the face, neck and chest, lasting a few minutes. They can come at any point in pregnancy and are more noticeable in the second and third trimesters.
Night sweats. Waking damp, or with the sheets wet, then feeling chilled once the sweat cools. This is one of the reasons late-pregnancy sleep fragments.
Heat intolerance. Finding rooms, buses and shops unbearable that everyone else finds fine.

When night sweats deserve a separate look

The NHS has a general page on night sweats and it lists reasons to see a GP that hold true in pregnancy: night sweats that regularly wake you or worry you; night sweats alongside a very high temperature or feeling hot, cold or shivery, a cough or diarrhoea; and night sweats with unexplained weight loss.

It defines the term more tightly than everyday use does. Night sweats are "when you sweat so much that your night clothes and bedding are soaking wet, even though where you're sleeping is cool" — not simply being warm because the room is warm.

What helps

The NHS suggestions are simple and are the ones worth doing:

Wear loose clothing made of natural fibres, which are more absorbent and breathable than synthetics.
Keep your room cool — a fan is specifically suggested.
Wash frequently to help you feel fresh.

Practical additions that follow from the same logic: keep water by the bed, layer bedding so you can shed it without waking fully, choose cotton rather than brushed or synthetic sheets, and cool your wrists and the back of your neck rather than trying to cool the whole room.

One caution on cooling: the NHS advises against hot baths, saunas and hot tubs raising your core temperature in pregnancy, so a cool or lukewarm shower is the sensible move rather than a long soak either way.

Why it is worse at night

Core body temperature falls slightly in the evening as part of the normal sleep cycle, and the body sheds that heat through the skin. In pregnancy there is more heat to shed and more blood at the skin to shed it with, so the same nightly process produces a bigger effect. Add a duvet chosen before you were pregnant and a partner generating their own heat, and the result is waking damp at two in the morning. It is also why the sweats often stop being a problem within days of the birth, and why the NHS keeps its advice on the room and the bedding rather than on treating you.

Heat, dehydration and the symptoms that follow

Sweating more while drinking the same amount is a slow route to dehydration, and dehydration produces a cluster of symptoms that then get blamed on pregnancy itself: headaches, light-headedness, dark strong-smelling pee, and a run of tightenings across the bump. The NHS advice to drink plenty of non-alcoholic, caffeine-free drinks during the day sits behind several other symptoms as well as this one.

When feeling hot is a warning

Two patterns move this out of the ordinary category.

Hot with shivering. The NHS puts shivering and chills in the same list as a thermometer reading of 38C. Tommy's names chills as a common sign of a high temperature, alongside sweating, headache, fatigue and muscle aches. Feeling hot and cold in waves, with shivering, is the classic presentation of an infection taking hold, and in pregnancy that includes urine infections, flu and COVID.

Hot with anything else on the red-flag list. The HSE names "pain when peeing, high temperature, or needing to pee more than normal" among the symptoms that need immediate contact with your midwife, GP or obstetrician.

Feeling generally warm, sweating more, and finding summer harder than usual is the normal version. A number on a thermometer, or shivering, is the version that needs a phone call, and it is not worth waiting until morning to make it.

Feeling Hot in Pregnancy and Night Sweats