Diarrhoea in Pregnancy

When to call, and when it can wait

Diarrhoea on its own, for a day or two, is usually a stomach bug and usually settles. What matters is the company it keeps. Tommy's splits the advice into three tiers, and they are worth having in that order.

Speak to your GP, midwife or maternity unit as soon as possible if you have diarrhoea together with any of these:

• a fever
• stomach pain
• very dark wee
• bloody diarrhoea, or any bleeding from your bottom

Tommy's names the reason plainly: "You may have dehydration or a gastrointestinal problem, and need treatment."

Call your GP for advice if you cannot keep any fluids down, if the diarrhoea or vomiting has not gone within 48 hours, or if you have a bowel condition such as IBS or IBD, so your medicines and care can be reviewed.

Call 999 if you vomit blood or bring up something that looks like ground coffee, if your vomit is green or yellow-green, if you have a stiff neck and pain looking at bright lights, or if you get a sudden severe headache or stomach ache. Contact your GP or NHS 111 for small streaks of blood in vomit.

The pregnancy-specific overlaps most articles miss

Diarrhoea is on two separate NHS red-flag lists in its own right, because it can sit alongside things that have nothing to do with a stomach bug.

The NHS page on vaginal bleeding tells you to get urgent help if you are pregnant and have light bleeding or spotting together with diarrhoea, or with pain or pressure when you pee or poo. That is not a stomach-bug instruction; it is an early-pregnancy one.

The NHS page on stomach pain tells you to call your maternity unit immediately if stomach pain comes with regular cramping or tightenings, lower back pain, unusual discharge, or pee that looks cloudy, pink, red or brown. Loose bowels plus cramping plus backache before 37 weeks is a pattern worth taking seriously rather than filing under "something I ate".

The HSE lists "pain when peeing, high temperature, or needing to pee more than normal" among the symptoms that mean contacting your midwife, GP or obstetrician immediately.

What is actually happening

Most acute diarrhoea in adults is infective gastroenteritis. NICE's Clinical Knowledge Summary describes it as a transient disorder caused by enteric infection with viruses, bacteria or parasites, and viruses are the usual culprit. Pregnancy does not make you catch more bugs, but it does change how much slack your body has when you lose fluid.

The other pregnancy-flavoured causes are duller. A change of diet, iron supplements, the rebound after a run of constipation, and in late pregnancy the loosening of the bowels that can precede labour. None of those explain a fever.

How long it should last

The NHS gives plain timings for adults: diarrhoea usually stops within five to seven days, and vomiting usually stops in one or two days. Tommy's is more specific about the pregnancy question people actually want answered: "It is very unlikely that your baby will be harmed from a stomach bug lasting less than 48 hours."

Beyond 48 hours the calculation changes, which is why the 48-hour mark appears in the "call your GP" tier rather than the emergency one.

What helps

The NHS advice for adults is deliberately unglamorous, and it applies in pregnancy:

• Fluids above everything. Water or squash, in small sips if you feel sick. This is the whole treatment, and the reason most people end up needing help is that they stop drinking.
• Rest at home.
• Eat when you feel able to, avoiding fatty or spicy food. Tommy's adds a reassuring line for anyone who cannot face food at all: "If you don't eat for 24 hours, don't worry, but make sure you drink plenty of fluids."
• Skip fruit juice and fizzy drinks, which the NHS says can make diarrhoea worse.
• Paracetamol can be used for discomfort. Ask your midwife or pharmacist before taking anything, and check the packet.

The medicine to ask about first

This is the practical point that sends people to a pharmacy shelf and gets it wrong. Tommy's is explicit: do not take medication to stop diarrhoea in pregnancy, such as loperamide, without speaking to your GP, midwife or pharmacist first, because these medicines are not usually recommended in pregnancy and it is unclear whether they are completely safe.

It also adds the sentence that stops the spiral if you have already taken some: "If you have already taken this type of medication while pregnant, there's no need to worry. No extra monitoring will be needed."

A pharmacist can help with rehydration powders, which are a different thing entirely and are the sensible first purchase.

Signs you are getting dehydrated

The NHS lists dark, smelly pee or peeing less than usual as the signs to act on. Dehydration is also the mechanism behind several things that get blamed on pregnancy itself: headaches, light-headedness and a run of tightenings across the bump.

If you are being sick as well as having diarrhoea and cannot keep fluids down, that is the point to ring rather than to wait it out.

Not passing it on

The NHS says to stay off work or school until you have not been sick or had diarrhoea for at least two days, wash your hands with soap and water frequently, wash affected clothing and bedding separately on a hot wash, avoid preparing food for other people, and stay out of swimming pools for at least 48 hours after symptoms stop. Tommy's repeats the same two-day rule for pregnancy.

The short version

A 24 to 48 hour bug with no fever, no bleeding, no tummy pain and normal-coloured wee is the common case, and drinking steadily is the treatment. Fever, blood, dark wee, tummy pain, tightenings or an inability to keep fluids down move it into the call-today category. And ask before you buy anything that stops diarrhoea.