He was potty trained at 27 months. By 30 months he was dry through the day, asking for the toilet, sometimes even going by himself. Then his sister was born.
Within two weeks of bringing the baby home, he had wet himself three times in one morning. By the end of the first month, he was averaging two accidents a day. By month two we had given up and put him back in pull-ups during the day, hating ourselves and hating the situation.
This is potty training regression. It hits roughly half of toddlers within a year of being trained, and almost always around a major life change. Here is what is happening and how we got out of it.
Why potty training regression happens
Regression is not your toddler forgetting how to use the toilet. He still knows. He just stops doing it for one of four reasons, and usually a combination.
The new baby. This is the single biggest trigger. A new sibling means less of your attention, and a toddler who was dry six weeks ago figures out within days that wee on the floor gets you in the room with him within 30 seconds. It is not manipulation. It is regulation. He is trying to recreate the closeness that has shifted.
Any major change. Moving house, starting nursery, a parent's work change, illness, a holiday, even a new bed in the same room can trigger it. The toddler nervous system processes change through familiar regressions. Potty training is one of the most recent skills, so it is the most fragile.
Constipation. This is underdiagnosed. Toddlers who hold poo for days (very common at this age) start to lose sensation in the lower bowel, which affects bladder signals too. If he is doing fewer than four soft poos a week, that may be your actual problem.
Pure power. Around age 3, toddlers discover that what comes out of their body is one of the very few things they completely control. If he feels controlled in other areas of life (rules, eating, screen time, baby intrusion), the potty becomes a quiet protest. Again, not manipulative, just developmental.
The 5-step reset that worked in under 2 weeks
You do not need to potty train from scratch. You need a much shorter reset.
Step 1: Do not punish, do not scold, do not show frustration on your face
This is the most important step and the hardest. Every reaction you have to an accident teaches him that wee is a way to get a big reaction.
When he wets himself: flat face, calm voice, "okay, let's get you changed." That is it. No "what happened?" No "you knew you needed to go!" No long discussion. Strip the wet clothes, wipe him down, put dry clothes on, carry on with the day.
The first week of doing this is brutal because the calm response feels unnatural. Do it anyway. Within 10 days the accidents drop by half on this alone.
Step 2: Reintroduce scheduled potty trips
For two weeks, go back to the scheduled trips you used during training. Every 90 minutes, say "let's go for a wee." Do not ask if he needs to go. The answer will be no. Just go.
This is not infantilising him. It is rebuilding the body-brain link that the stress disrupted.
Step 3: Give him 10 focused minutes a day, just him
If the regression started after a new baby, this is the single highest-impact thing you can do. Ten minutes a day of completely focused, phone-down, baby-not-present time. Doing whatever he wants. He picks the activity.
It feels insufficient. It is not. The need underneath the regression is "I am still important." Ten genuine minutes of "I see you" satisfies that need better than two hours of distracted presence.
If you cannot do it daily, three or four times a week is still significantly better than not at all. The partner can also do it, but ideally most of the sessions come from the parent he has bonded with most closely.
Step 4: Check for constipation
This is a quick conversation worth having even if you do not think it applies.
How often does he poo? Soft or hard? Big or small? Does he strain or refuse to go?
If he is going less than every other day, or his poos are hard like rabbit pellets, or he is straining and crying, treat for constipation first. Speak to your GP about Movicol (a gentle stool softener used in young children, considered safe long-term and widely prescribed). Adding more water and softer fruits like pear and kiwi helps but is often not enough on its own.
Most toddlers with mysterious wetting regression have undiagnosed constipation. Treating it sometimes resolves the wee accidents within a week.
Step 5: Stop talking about it
Once the schedule and the focused time are in place, stop mentioning potty training in his hearing. Do not tell relatives about the accidents in front of him. Do not say "you used to be such a big boy with this." Do not make it a topic.
The less he hears the words "wee," "potty," and "accident" attached to him, the faster the behaviour resolves. Big children whose parents are very calm about it forget the regression happened. Children whose parents are very vocal about it can hold onto the pattern for months.
What if it lasts more than 3 weeks
If you have done all five steps consistently for three weeks and accidents are still happening daily, the issue may not be behavioural. Worth a GP visit to check for:
- Urinary tract infection (especially if accidents come with smelly urine, fever, or stomach pain)
- Worms (common in toddlers, can cause sudden wetting and itchiness around the bottom)
- Chronic constipation that needs medical treatment
- Less commonly, kidney or bladder issues that show up as suddenly wetting
A GP visit is reassuring even when nothing is wrong. Most of the time something simple is found and treated.
When night-time also regresses
Night-time dryness is a different process than daytime, and night-time regression usually means you were lucky to be dry at night to start with rather than truly trained. Most children do not have full night-time bladder control until between 4 and 7.
If he is wetting the bed after being dry at night, put pull-ups back on at night and treat daytime separately. There is no benefit to fighting the night-time regression. The hormone that controls overnight bladder filling matures on its own timeline and cannot be trained.
What to tell yourself in week 2
Regression is not failure. It is one of the most predictable side effects of any big change in a toddler's life, and it almost always resolves within 4 to 8 weeks of consistent, calm response.
Your son has not forgotten. He is processing. The wee on the kitchen floor is not aimed at you. It is a small body coping with a big change in the only way a 3-year-old knows how.
The new baby is the bigger story. The accidents are just a chapter of it, and the chapter is short. In two months, you will not remember how panicked you were about this, just like you do not remember how worried you were about the first round of training.
He is going to be fine. So are you.