After your baby is about 3 weeks old and you know she is gaining weight well, her poop frequency may start to change. This is often alarming for parents because their infant goes from having a bowel movement every time he eats to skipping a day or two between them.

Most babies this age are fussy intermittently anyway and parents associate this change in bowel habits to the fussiness so they e-mail or call me for advice.

I've got some good news: This is almost always normal and not worrisome. If your baby is still eating fine and not feverish, there's unlikely to be anything bad going on. What happens around 3-6 weeks of age is that babies get really efficient at digesting what they eat. This is especially true of breast-fed infants but even formula-fed infants will often experience a change in frequency at around this age. For the first week or so that this adjustment is taking place, your baby may be a bit fussier, but hang tight and nature will work things out. Within a week or two, a new pattern will be established and your baby will be just as content as ever.

How long is too long is the inevitable next question. The answer always shocks parents. For exclusively breast-fed infants, going up to 14 days without a bowel movement is not unheard of and going a few days between them is quite common. For exclusively formula-fed babies, most will skip a day or two at most and more commonly still have a bowel movement every day after the initial week of adjustment is done. As you probably guessed, babies fed breast milk and formula fall somewhere in between.

The hardest part for parents is when they feel their baby is fussy as a result of infrequent pooping even after a week or two. For those babies, sometimes encouraging a near daily bowel movement by using undiluted pear juice can help. For little infants who aren't yet eating solid foods, 2 ounces undiluted will usually do the trick. It can be used every day or just when needed and is a natural way to keep things moving.

I worry about babies with hard stools that are like pellets or adult stools regardless of frequency, or babies who cannot have a bowel movement without the aid of a suppository despite using pear juice and letting time do its work. Otherwise, if your baby will poop on her own, even if it is only once every week and half, as long as the stool is soft, your baby is eating well and gaining weight, I never worry.