How many bowel movements a day should a baby have, depending on their age? 

Early in life, a baby fed infant formula may have up to around five bowel movements a day. After a few months, this frequency often decreases, approaching once a day (1). 

Some babies fill their diaper more often than others. During the first few weeks, the number of wet diapers, your baby's weight gain and overall condition also provide important information about their nutrition (1). 

Is it normal for a baby not to poop every day? 

This can happen. Not having a bowel movement for one day does not automatically mean your baby is constipated. 

Frequency matters, but your child's texture and comfort are just as important. If they eventually pass a soft stool without any particular pain and continue to eat as usual, a slightly less frequent schedule is not necessarily a cause for concern. 

However, for a baby under 8 weeks who has not had a bowel movement for two or three days, it is recommended to seek advice from a healthcare professional (2). 

What do the stools of a baby fed infant formula look like? 

The stools of a baby fed infant formula generally do not look exactly like those of a breastfed baby. They tend to be thicker, darker and have a stronger odor (1). 

What color should the stools of a baby fed infant formula be? 

After the meconium of the first few hours, the color of the stools of a baby fed with a bottle may range from yellow to brown, sometimes with a green tint. Some formulas, in particular, may give a dark green appearance without this necessarily meaning that your baby is ill. 

Are you concerned about a change in color? Context matters a great deal: check whether your baby is eating normally, maintaining their usual behavior and showing no other signs. 

What consistency should a baby's stools have? 

They are generally firmer than those of a breastfed child, but they must remain soft enough to be passed without difficulty (1). 

A baby may strain, grunt or turn red for a few moments without being constipated. However, small hard pellets, a very hard texture or clearly painful straining are more likely to indicate constipation (2). 

How does infant formula affect your baby's bowel movements? 

The way your baby is fed naturally affects their bowel movements. This is why the contents of the diaper may change when a baby switches from breast milk to formula or when their diet changes. 

Why can infant formula change a baby's stools? 

Breast milk and infant formulas do not have exactly the same composition. Their digestion therefore leaves different residues in the intestine, which can explain differences in frequency, texture, odor and color (1). 

If you use powdered infant formula, carefully follow the water and powder proportions indicated on the box. Adding more powder does not make the bottle more nutritious and can promote constipation and dehydration (2, 3). 

The impact of a change in infant formula on stools 

After a change in formula, you may notice that your baby's habits are changing: a different appearance, a more or less pronounced color or a slightly altered schedule. This does not necessarily mean that the new formula does not suit them. 

Above all, pay attention to what changes compared to their usual routine. If your baby seems to be in pain, regularly refuses their bottle or has persistent symptoms, a healthcare professional can help you make the point. 

Baby constipation is not simply "not pooping every day". It is rather characterized by bowel movements that are too infrequent or difficult, with hard, dry or large stools, sometimes accompanied by pain, bloating or a reduced appetite (2). 

If your child has already started solid foodse, their diet also plays a role. Discover our advice on foods to give a constipated baby. 

However, avoid changing the proportions of the baby bottle yourself or giving a medication, suppository or any other solution without medical advice appropriate to your child's age. 

So a day without a full diaper is not necessarily worrying. It is mainly unusual changes and associated signs that deserve your attention. 

It is best to consult a doctor if your baby has blood in their stool, severe diarrhea, repeated vomiting, refuses to drink, seems to be in a lot of pain, or shows signs of dehydration. In a child under 2 years old, at least three loose stools in a few hours also warrant prompt medical advice (4). 

Similarly, if their bowel movements change permanently or if you are concerned about their growth, your doctor or pediatrician can advise you based on their age, diet, and overall health.

Is it normal for a baby fed formula not to poop every day? 

This can happen, especially as your baby grows and their bowel movements become less frequent. If their stools remain soft and they are otherwise well, a day without a bowel movement does not necessarily indicate constipation. However, if a baby under 8 weeks old has not passed a stool for two or three days, seek medical advice (2). 

Why do formula-fed babies' stools smell stronger? 

Formula and breast milk do not have exactly the same composition, which can lead to differences in digestion and the residue left in the bowel. As a result, the stools of a baby fed formula are often thicker and smell stronger than those of a breastfed baby. The smell alone is generally not a cause for concern if your baby is eating well, growing normally and showing no other symptoms. 

Why are formula-fed babies' stools firmer? 

In babies fed formula, stools are generally firmer than in breastfed babies (1). However, they should not become dry, hard or difficult to pass. Also, make sure that each bottle is prepared with exactly the recommended amount of water and powder (3). 

How can I tell if my baby is constipated? 

Pay less attention to the calendar and more to what happens when your baby has a bowel movement. Hard or pellet-like stools, painful straining, a firm or bloated tummy and an unusually reduced appetite may indicate constipation (2). 

Sources 

(1) NHS — Changing a nappy 

(2) Assurance Maladie — Recognising constipation in children 

(3) Assurance Maladie — Preparing a baby bottle correctly: measuring the powder and water 

(4) Assurance Maladie — Diarrhoea and gastroenteritis in children: what to do and when to see a doctor?