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Babies cry a lot, which can be really irritating but it's normal.  It's the only way they can tell you they're hungry or bored or tired or...you get the idea.  But some babies do cry more than others, and when an otherwise healthy baby cries more than normal, they're said to have infantile colic or be colicky, but as medically as that sounds, it doesn't mean the doctor knows what's causing all those tears.

Though we've been studying colic for decades, we still don't have a clear answer for why it happens, though more recently, research seems to suggest a link to migraines and that might finally help doctors figure out what parents can do about it.  The term 'colic' has been around for basically ever, but it wasn't really codified in the medical community until the 1950s.  That's when pediatricians came up with the rule of three, which many medical professionals still use today.  

Basically, it's colic if an infant cries for at least three hours a day, at least three days a week, for more than three weeks.  Colicky crying may also seem more intense than regular baby crying and like an expression of pain, and the usual things that console upset babies like food or diaper changes often have no effect.  As upsetting as colic may be, it's estimated that between 5 and 19% of infants and perhaps more, experience it, and the cause that seems the most obvious is tummy distress.

After all, colicky infants often pull up their legs to their chests and pass gas during episodes of crying.  That's even why it's called 'colic', it's related to the Greek root, kolikos, which means 'pertaining to the large intestine', but pinning down what tummy distress means medically has proven difficult.  

Colic doesn't seem to be gas-related for example.  Clinical trials using simethicone, a drug commonly used to treat painful gas, have found it's no more effective than a placebo, and other gastrointestinal explanations, like that some infants struggle to digest something in breast milk or formula, generally haven't panned out either.

Sometimes, babies who seem colicky may actually have a milk protein allergy or lactose intolerance, but that's thought to explain less than 5% of colicky infants, and outside of true milk allergies posing as colic, there isn't much evidence that what or how a baby is fed is to blame.  Since upset tummies didn't seem to explain all cases of colic, researchers have looked elsewhere. 

Maybe it's more of a psychological thing, like colicky infants are responding to high levels of family stress or have developmental lag in their ability to regulate emotion or they're just high-strung, but none of those ideas seem to explain the whole picture either, and slowly, researchers started to notice something else, something intriguing.  In a 1994 paper, for example, doctors in Pittsburgh described treating an infant with severe colic whose daily crying episodes were really intense.   In addition to inconsolable crying, the poor thing would scratch at her head and even vomit.  It turned out that a lot of her close relatives had experienced migraines, those super intense headaches that tend to be accompanied by other nasty symptoms like visual sensory disturbances, sensitivity to light and sound, and nausea.  So the doctors tried giving the baby a low dose of a migraine medication and it worked.

Studies since have found that there's a strong association between parental migraines and colic.  One from 2012 suggests that infants have more than double the risk of developing colic if their mother has migraines, and a web-based survey published in 2019 of over 1400 biological parents found the more migraines a mother experienced per month, the higher the odds were that her baby had colic, so it's possible that what we've been calling colic is really infant migraines, but that doesn't tell us what the babies are actually experiencing.

You see, migraines are kind of enigmatic to begin with.  We don't fully understand why they happen or why people experience them differently, and on top of that, we can't ask an infant if they're crying because they're head hurts a lot or if they're being freaked out by sensory disturbances.  It could even be their bellies after all.  

It's estimated that between one and nine percent of children and some adults who have migraines, experience what are called abdominal migraines.  Basically, they get all the usual joys of migraines plus pain in their abdomen.  Why they feel migraines in their bellies isn't clear, but there's a lot of connections between your head and your stomach.  The two are so intertwined that there's even a term for it: the gut-brain axis.

So doctors think abdominal migraines may occur because something goes wrong somewhere in that axis.  While all of this makes migraines sound like a solid explanation for colic, there isn't actually a lot of smoking gun evidence.  We can't look at test results and say, yep, those infants are definitely having migraines.  It's also entirely possible there's something else going on, it's just related to migraines.

There seems to be an important connection between migraines and a lot of gastrointenstinal disorders like Irritable Bowel Syndrome and Inflammatory Bowel Disease, plus, multiple studies suggest the gut microbiome may play a role in colic, migraines, and other gastrointestinal disorders.  Basically, doctors are pretty sure these pieces all fit together somehow, we're just not exactly sure how.

Luckily, even without a fully assembled puzzle, the migraine piece does suggest some practical ways to manage colic.  Basically, you might try things that help older kids and adults with migraines, like steering clear of loud music and noise, dimming bright lights, and avoiding strong smells, like that safe jiggling or bouncing that some parents do while supporting a baby's head, while it can soothe crying infants, it could be overstimulating to babies with colic, so gentle rocking might be a better approach, but also, if you have a colicky baby, keep in mind that it's okay to take a break if the crying feels overwhelming.

Like with migraines, there may not be a whole lot you can do to soothe them.  That's why pediatricians say you can set a crying baby down in a safe space like a crib or a playpen and just step away from a minute if you need to.  Protect your mental health, and if nothing else, rest assured that infant colic doesn't last forever, even if it seems like it will.  By four months of age, most cases of colic have improved or resolved entirely.  Then it's just, you know, the whole rest of parenthood you have to deal with.

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