Period-Like Cramps in Late Pregnancy

Under 37 weeks: call your maternity unit

The NHS puts period-type pains directly on its premature labour list. Its urgent-advice box says to call your midwife or maternity unit if you are less than 37 weeks pregnant and you have:

• regular contractions or tightenings
• period-type pains
• a gush or trickle of fluid from your vagina — this could be your waters breaking
• backache that is not usual for you

It adds: "You can also call your midwife or maternity unit if you're unsure or worried about anything."

The NHS stomach pain page repeats it: "If you're less than 37 weeks pregnant and are having regular abdominal cramps or tightenings, call your maternity unit immediately. This could be a sign of premature labour, and you'll need to be monitored in hospital."

The HSE gives the same instruction from the third-trimester side: contact your GP, maternity unit or hospital if you are less than 37 weeks pregnant and getting regular contractions that are not going away or are getting stronger.

For scale, the NHS says: "About 8 out of 100 babies will be born prematurely." This is not a rare scenario, and maternity units expect these calls.

Also call immediately if cramps come with

• vaginal bleeding or spotting
• lower back pain
• unusual vaginal discharge, or fluid leaking
• pain when you pee, or pee that looks cloudy, pink, red or brown
• pain that is severe, or does not settle after resting for 30 to 60 minutes
• any change in your baby's movements

The NHS bleeding page adds that bleeding with severe tummy pain, shoulder pain, feeling faint or heavy bleeding is a 999 call.

What Braxton Hicks feel like by comparison

The HSE gives the clearest description: "By the third trimester you may feel pain-like contractions called Braxton Hicks. These do not happen at regular intervals. They tend to be short, lasting about 30 to 60 seconds. They are not labour pains and are not usually very intense. You might feel discomfort rather than pain."

So the features of the harmless version are: irregular, short, not building, not intensifying, and usually more tightening than pain. They often stop if you change what you are doing — lie down if you have been active, or get up and move if you have been still.

The HSE's non-urgent advice line is a useful middle marker: contact your midwife, maternity unit or hospital if you have contractions that are intense and painful, less than 10 minutes apart, and not going away.

The honest limitation of this comparison

Plenty of people cannot tell the difference, and no amount of description fixes that. That is precisely why the guidance is worded as it is: before 37 weeks, the instruction is to ring rather than to work it out yourself. Monitoring settles in twenty minutes what description cannot settle at all.

Other reasons for cramping late on

Once preterm labour has been excluded, several ordinary causes remain.

• Constipation. The HSE names it directly for the third trimester: "By now, your growing baby and womb may be putting pressure on your gut. This might make it more difficult for you to poo." It suggests high-fibre foods and advises talking to your GP, midwife or pharmacist about medicine to help.
• Trapped wind. Named by the NHS among the harmless causes of stomach pain.
• Urine infection. The NHS says UTIs can cause tummy pain and sometimes, but not always, pain when you pee.
• Ligament and muscle strain, particularly after a busy day on your feet.
• Dehydration. A reliable and under-recognised trigger for a run of tightenings. It is also the easiest to test: drink, lie on your side, and see whether they settle.

Why dehydration is worth testing first

Of all the harmless causes, dehydration is the one most likely to produce a convincing run of regular tightenings, and it is the only one you can act on in five minutes. A large glass of water, lying on your left side, and half an hour of quiet is the standard first move while you are on the phone or waiting to be called back. If the tightenings space out and fade over that half hour, dehydration or activity was almost certainly the driver. If they carry on or get closer together, that is exactly the information the maternity unit wants.

After 37 weeks

The calculation changes once you are term, because labour is no longer something to prevent. The HSE says to contact your midwife, maternity unit or hospital immediately if you are more than 37 weeks and you think you are in labour, your baby's movements change, your contractions are five minutes apart and getting stronger, or your waters break.

The NHS lists the signs that labour has begun as contractions or tightenings, a show, backache, an urge to go to the toilet caused by the baby's head pressing on the bowel, and waters breaking.

Period-like cramping at 38 weeks with a show is a promising development rather than a worrying one. The same sensation at 30 weeks is a phone call.

What to do in the next ten minutes

If you are under 37 weeks and having period-type pains, ring. If you want to gather information while the phone rings:

• Note the time of each tightening and how long it lasts. Regularity is the thing you will be asked about.
• Check your pants for bleeding or fluid.
• Empty your bladder and drink a glass of water.
• Lie on your side and pay attention to your baby's movements.

If everything settles within the hour, mention it at your next appointment anyway. If it does not, the call has already been made, which is the correct order.