Nappy blowouts are an all-too-common rite of passage for new parents—especially during the newborn months when babies are on an all-liquid diet and have frequent, runny poos. While the occasional blowout is unavoidable, there are smart strategies you can use to keep messes to a minimum. Here’s what you need to know about why nappy blowouts happen, how to prevent them, and what to do when your little one lets one loose.

What is a nappy blowout?

If you’re asking this question, congratulations—you’ve yet to experience the full force of an up-the-back poo explosion! A nappy blowout is exactly what it sounds like: a full-scale poonami that escapes the nappy and travels up baby’s back, down their legs, or, if you’re really unlucky, both. Blowouts can affect all babies—whether they’re breastfed or formula-fed—and are especially common in the early weeks when poos tend to be more liquid.

What causes nappy blowouts?

  • Runny poo: Newborns and young infants have soft, often explosive stools, particularly if they’re breastfed. As solids are introduced, poos generally become more formed, which helps reduce the risk of blowouts.
  • Gas or constipation: Built-up pressure from wind or constipation can lead to powerful poos that even the best nappy struggles to contain. (Find tips for relieving baby constipation.)
  • Diarrhoea: If your baby has diarrhoea, it can be difficult for any nappy to keep everything in. In this case, it’s best to speak with your GP or child health nurse, especially if it lasts more than a day or two.
  • Incorrect nappy size: A nappy that’s too small or too loose is more likely to leak from the sides or back.

Do blowouts mean the nappy is too small?

Often, yes. Frequent blowouts could be a sign that your baby needs the next nappy size up. Nappies that are too snug may not provide enough absorbency or fit properly around the thighs and waist—leaving gaps for poo to escape.

How to Check Your Baby’s Nappy Fit

  • The waistband should sit just under baby’s belly button without being too tight or too loose.
  • The leg cuffs should hug baby’s thighs with no gaps. Be sure to pull the ruffles out—they’re there to help contain messes!
  • If leaks or blowouts are happening often, try the next size up.

How to Prevent Nappy Blowouts

Use the right size

A well-fitting nappy is your first defence. Too small, and there’s not enough material to soak up liquid; too big, and gaps may allow leaks before the material can do its job.

  • Check the weight range on the nappy packaging and size up if needed.
  • The nappy should fit snugly around the waist and thighs without leaving red marks.

Check your nappy fastening

Even the best nappy won’t work if it’s not put on correctly.

Checklist:

  • Waist and legs should fit snugly.
  • The waistband should sit at or just under baby’s belly button.
  • The back should sit slightly higher than the front. Some parents roll the back outward for extra protection.
  • You should be able to slip one finger between the nappy and baby’s skin.
  • Always pull out the leg ruffles to create a secure seal.

Change nappies regularly

Leaving a nappy on too long increases the chance of a blowout, especially if it’s already full. Aim to change your baby every 2 to 3 hours or whenever the nappy is soiled. Be especially alert after feeds—feeding often gets things moving!

Try different nappy brands

Not all nappies fit all babies the same. If one brand isn’t working for your little one’s shape, try another. You may also want to look for nappies with elasticised waistbands and leg cuffs for better containment.

Consider nappy covers or blowout blockers

Some parents use cloth nappy shells over disposables or special blowout blockers for extra insurance—especially during naps or outings. Just make sure any cover you use fits snugly without being too tight.

Monitor diet and digestion

Once solids are introduced, stool consistency and frequency can change. Introduce new foods gradually and take note if any seem to trigger blowouts. If you’re seeing persistent diarrhoea or constipation, have a chat with your GP or child health nurse.

How to Handle a Nappy Blowout

  • Stay calm: Blowouts are messy but normal. Deep breaths help…just maybe not right over the nappy.
  • Keep a blowout kit handy: Include spare nappies, wipes, a change of clothes for baby (and you), plastic bags, a change mat, and a waterproof zip-top bag.
  • Take clothes off carefully: Use envelope-style necks on bodysuits to pull them down over baby’s body—not over the head.
  • Use a warm flannel: Reusable cloths can be gentler and more effective than wipes.
  • Protect your changing area: Use a towel or waterproof mat before you get started.
  • Head for the bath: For major messes, it may be easier to skip the wipes and go straight to the tub.
  • Learn and adjust: Consider what your baby was wearing, how the nappy was fastened, and whether they were due for a change. It might help prevent a future mess.

More Nappy Know-How:

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Disclaimer: The information on our site is NOT medical advice for any specific person or condition. It is only meant as general information. If you have any medical questions and concerns about your child or yourself, please contact your health provider. Breastmilk is the best source of nutrition for babies. It is important that, in preparation for and during breastfeeding, mothers eat a healthy, balanced diet. Combined breast- and bottle-feeding in the first weeks of life may reduce the supply of a mother's breastmilk and reversing the decision not to breastfeed is difficult. If you do decide to use infant formula, you should follow instructions carefully.