Resolving Colic

Colic is hard to explain to parents who haven’t had the pleasure. The most widely accepted definition is the “Rule of Three (1):” crying at least 3 hours per day on at least 3 days of at least 3 weeks. Other definitions include, “severe crying for several hours per day (2),” “crying for more than two hours per day (3),” and “cumulative cry duration of 3 hours per day (4).” But these quantitative sets of rules completely fail to encapsulate the colic experience, which includes severe infant distress, and parental overwhelm and depression that can become so severe it leads to child abuse (5). Around 1 in 5 infants suffer from colic, so you have a pretty good chance of enduring it, if you haven’t yet. The crying typically appears when the infant is 2-3 weeks old, peaks at six weeks, then gradually declines, disappearing around 3 or 4 months of age, but the timing can vary a lot.

A colicky child may or may not be quick to cry. He may not cry about anything all day, and then every night at 7pm will cry non-stop for 3-4 hours for no discernible reason. This is what makes colic so hard to define. Patterns and duration of crying vary so much between colicky infants, that it is probably best to trade in definitions of colic that involve a timer for more qualitative descriptions. Personally, I think “inconsolable” is the defining characteristic of colic. Some children are more sensitive than others, placing them high on what might be called the infant cry spectrum. But there’s a huge leap between an infant who is quick to cry and one who has colic, because a child with colic is inconsolable. No matter what the parents do, the baby will continue his gasping, body wracking sobs for perhaps hours.

The only form of communication a baby is born with is crying. They cry before they smile. Communicating distress is essential for infant wellbeing and survival. We parents are programmed to attend to the distress of our infants, and have a more intense physiological response to infant cries than laughs (6), which is precisely why colic is so painful for us as parents. We are viscerally (7) affected by infant cries, only finding relief once the crying stops. Which means we will share in our colicky child’s months-long suffering. This means effective colic management must focus on supporting both the parents and the infant.

Understanding where the colic is coming from can help you both reduce the crying and empathize, unlocking the even-tempered child beneath the tears.”



Despite What You’ve Heard, Colic Has Discernible Cause and Effective Remedies

Babies don’t just cry. They cry for a reason, which can be determined with some detective work. There are many available treatments for colic. Some, like Simethicone and gripe water, don’t work (8,9). Some DO work, but have dangerous side effects (10), like herbal supplements and antispasmodic drugs. A number of treatments, however, are both safe and very effective, in SOME cases. There are several different causes of colic, so every remedy will only work for the infants who happen to be suffering from the matching ailment. Discerning the cause of colic is therefore essential to finding the appropriate remedy.    
 

Despite What You’ve Heard, There ARE Long Term Consequences of Colic

Infants with colic are at higher risk of: being more difficult as toddlers (11) (judged by tantrum frequency), suffering sleep disorders (12), becoming either aggressive, or fearful and withdrawn (13), developing feelings of supremacy (14) (needing to be better than everyone else), and cognitive deficits (15, 16) (also see here). Long-term consequences of colic have been detected even in 10 year olds.

I don’t know why so many baby expert sites (17) claim there are no long-term consequences, except perhaps for the well-intentioned goal of reducing parental stress. And reducing parental stress is important, because the most dangerous risk to colicky infants is child-abuse (18) that can result in long-term brain damage, or even death (5,19). By convincing parents that colic is not serious, experts may hope they will be more inclined to follow instructions to “put the baby down in a safe place and take a break when you feel overwhelmed (before you shake the baby to death).” Worrying about long term consequences may only lead to further overwhelm and anger (fear leads to anger, anger leads to hate, you know the rest...). And parental overwhelm is what leads to all the long-term consequences of colic, from difficult temperaments later in childhood to shaken-baby-syndrome. 

It can be tempting to believe, when in the thick of it, that a colicky child has ruined your happiness, is not the child you hoped for, is broken, or that you have been saddled with a difficult dependent for life. You must remember that these are both false assumptions and self-fulfilling prophesies.”

You will sometimes read that colicky babies may simply have more difficult temperaments (20), predetermined by their genetics, expressed as colic in infancy and then as terribleness during the twos. Don’t for one second believe that. If colic were caused by infant disposition, then we would see colic in all cultures around the world, and we don’t. It is an affliction unique to modern life (21), and with higher prevalence among parents in difficult circumstances (we’ll come back to this). If you believe the lie that colicky infants just have “bad” dispositions, unfounded resentment for your child will grow. It can be tempting, when in the thick of it, to believe that a colicky child has ruined your happiness, is not the child you hoped for, is broken, or that you have been saddled with a difficult dependent for life. You must remember that these are both false assumptions and self-fulfilling prophesies. This negativity impacts the long-term development of your child, because it damages your parent-child relationship and interferes with your ability to support your baby and yourself through the painful experience he’s going through. Conversely, empathy, love, and understanding have the power to mitigate and even avoid these long-term negative outcomes. And I’ll give you the science to prove it.

Colic, unsurprisingly, is strongly correlated with maternal depression (22), and it’s well established that maternal depression causes insecure parent-child attachments (23). Interestingly, the negative long-term child outcomes associated with maternal depression (24) and insecure parent-child attachments (25) happen to be the very same as those associated with colic. Which strongly suggests that the depression and disrupted parent-child attachments associated with colic are the true perpetrators of these negative cognitive and temperament outcomes (26), not the colic itself. (“Attachment” refers to relationship intimacy. Styles of attachment can be “secure,” meaning skilled at promoting and maintaining intimacy, or “insecure,” meaning emotional defenses damage intimate relationships. An “insecure” parent-child attachment is one in which a parent’s intimacy with, and responsiveness to, his child is obstructed. See here for more info (27)).

In summary, colic has the power to cause or magnify maternal depression (28), fracture parental relationships (also here (29,30)), and taint a parent’s affection for his/her own baby. THIS is why colic can have a lasting impact on infants and their families, not the crying itself. When dealing with colic, take a longer view. Managing the crying is less important than managing your relationship with your child. Understanding where the colic is coming from can help you both reduce the crying and empathize, unlocking the even-tempered child beneath the tears. Empathy is a great weapon against resentment, and an essential tool in building secure parent-child attachments. 

Coincidentally, the negative long-term outcomes associated with colic are also the long-term outcomes associated with maternal depression and insecure parent-child attachments.”

Colic Causes

Is It Your Parenting Style?

I don’t mean to be rude, but it’s worth considering in some cases. Research shows that coaching parents (31) on how to respond to their colicky infant can reduce hours cried well below the “Rule of Three” threshold. Research has also found that infants are at a higher risk of developing colic if they are born to parents who believe babies cry to manipulate, or who believe parents can spoil a child through affection (32). This means that some infants who are deemed colicky do not have true colic by our definition of inconsolable crying, but only by standard definitions like the "Rule of Three." These children ARE consolable, but their parents are not consoling them because of their personal beliefs about spoiling, or feeling manipulated. If you have concerns about your baby manipulating you, or about spoiling your child, let me put your mind at ease.

The act of manipulation requires an understanding of the psychology of the victim. Infants do not have the ability to understand another person’s psychology. They won’t even have an understanding of cause and effect until after colic has passed. A six-month-old should understand that when he cries you will comfort him (if you’ve done your job). But that is not manipulation. The six-month-old has learned how to get what he needs by observing patterns of cause and effect, but he doesn’t have any awareness of what is going on in your head. Just like when you push the button on the toaster you know it will toast your bread. Are you manipulating the toaster? I guess it depends on your definition, but definitely not in the conniving sort of way some parents think their babies are manipulating them. You wanted toast and you’ve observed the pattern: push toaster-button --> toast! A 6-month-old who cries for you is merely following the learned cause-effect protocol to get his needs met, which is what a healthy 6-month old should do. A newborn who cries has an unmet need, and is simply expressing it according to instinct, without any kind of forethought, reflection, or planning. Kids don’t develop the capacity to be “conniving” until far later in childhood.

As for spoiling, there are now mountains of research that show us the more emotional support an infant or young child receives, the more emotionally resilient (33) the child will become, which is exactly OPPOSITE of what our parents and grandparents were told. A child who has a secure emotional base has more courage to go out and explore, take risks, and manage stress. Your responsiveness during infancy and early childhood builds the foundations for resilience later on. Feel free to invest a lot in this front-end foundation building if you’re shooting for rearing a sturdy individual.

So, if your baby is crying a lot and you haven’t tried giving her what she’s asking for, try it! Maybe she is hungry, or scared, or has gas. Feed on demand (hunter-gatherers living like our ancestors feed infants every 13min (34)). Hug on demand. Carry her around in a wrap if she likes it. Bicycle her legs until she farts. Burp her. Coo and sing. Talk and play. If your child is consolable using any of these methods, your child doesn’t have colic. She just needed those awesome parenting skills you were holding back.

Is It Physical Pain?

Some physical causes of colic are GERD or reflux, or other forms of gastrointestinal upset. A physician can examine your child for reflux or food allergies, but other kinds of GI upset may be harder to deduce.

For example, the immature infant gut can be sensitive to proteins that are “unnatural” for infants to consume. These proteins cause excessive inflammation of the infant gut lining, which causes gas and cramping. This is sort of like an allergy, but is more accurately called a “sensitivity” that will pass as the gut matures. Colic is as common in breastfed infants as it is in formula-fed infants because the irritating foods are found as often in formula as they are in the breastfeeding mother’s diet. Cow milk protein is the most common irritant, but other foods can cause problems as well (35, 36). Some research also suggests that imbalances in the gut microbiome can give infants intestinal discomfort, but the research isn’t consistent (37).

Your baby’s colic could be a manifestation of your own emotional suffering.”

Is It Emotional Pain?

Colic can also have neuroendocrine causes, meaning the crying is caused by emotional pain. (Our neuroendocrine system is what produces the chemicals of emotion: hormones and neurotransmitters. Think cortisol, dopamine, serotonin, etc.) Colic is 3x more common (38) in women who were depressed or severely anxious during pregnancy. This is because infants mimic (39) their mother’s neuroendocrine profiles at birth (have the same emotional chemistry as mom), and because mom’s prenatal emotional state influences development of her baby’s neuroendocrine system (also see here (40,41)). Which means your infant’s colic could be a manifestation of your own emotional suffering. This emotional pain most often comes from relationship stress or feeling unsupported (42), but it can also come from financial or job stress (43), or anything that makes mom chronically and acutely upset. Sometimes the stress may manifest as “pregnancy anxiety” (paranoia about the pregnancy failing or the infant dying during labor). This is a truly vicious cycle. The stress mom felt during pregnancy is now pouring out of her infant, toppling already crumbling romances and making mom far MORE stressed and overwhelmed than she felt before. Which only aggravates the difficult dynamic between her and her colicky infant.

Research shows infants of depressed or anxious mothers often have over-reactive hypothalamic-pituitary-adrenal (HPA) axes (also see here (44,45)). The HPA axis is our stress-response system. Our stress hormones can make us feel stressed, but they also make us feel alert. So think of these infants as hypersensitive not just to stress, but to stimuli in general. Infants with hyperactive HPA axes can have difficulty falling asleep because they are overstimulated by their surroundings, and so regularly become overtired. Over-tiredness may be more responsible for crying than disposition or hypersensitivity.

Research also shows that normal circadian (or daily) rhythms of cortisol and serotonin (46,47) are out of whack in colicky infants relative to other infants. These hormonal imbalances may cause gut cramping, inability to sleep due to hyperactivity, and the inability to regulate emotions. Disrupted hormonal cycles, combined with hypersensitivity and over-tiredness, may all contribute to the “Witching Hour,” which is actually several hours every evening during which many colicky babies routinely cry.

Disrupted hormonal cycles, combined with hypersensitivity and over-tiredness, may all contribute to the ‘witching hour,’ which is actually several hours every evening during which many colicky babies routinely cry.”

Permanently Touchy Temperament?

Even if you can’t change how much your baby cries today (note: I think you can), the way you respond to your infant actually DOES change how much crying you will have to tolerate down the road. Research shows the amount a baby cries at birth does NOT predict how much he will cry at 1 year. What DOES predict how much a one year old will cry? How responsive his parents were when he cried in infancy! What a beautiful example of how nurture can override nature.

Even parents who can’t stop their child from crying can reap the long-term benefits of attentive care. It turns out that just being present is enough.”

Children with parents who responded quickly and consistently to cries in the first year cried LESS (48) at one year than children whose parents rarely responded to cries, or who took a long time to respond. How much the children cried as newborns was actually totally irrelevant after a year. This means how much your colicky infant is crying today has little bearing on your future tantrum exposure. How well you treat him has the power to change it all. The most encouraging part of this research is that it didn’t matter if a parent was actually able to console her child. Even parents who couldn’t stop their child from crying could reap the long-term benefits of attentive care. It turns out that just being present through the crying is enough.

This research was my salvation during our own colic weeks, because it gave me a sense of self-efficacy. This data told me to trust that I WAS being effective when I soothed my daughter, even if I couldn’t see my impact yet. Much of my stress came from feeling helpless, ineffective, and incompetent, a sentiment reflected in most parents of colicky babies. This research calls for a GOAL SHIFT. Your primary goal is not to get your child to stop crying, but to show her that she has support. Stopping a colic cry is an unattainable goal until you identify the cause. Allowing a child to cry on your shoulder is very attainable. Stop exhausting yourself futilely trying every soothing strategy under the sun, and relax with your crying baby. (I say “relax” in the relative sense- we’re going for regaining normal breathing rate, not a state of Zen.) Have faith that when you just sit with her, you are healing her.

Colic casts a curse that breaks our attunement with our child.”

Some mothers claim it took them years to heal (49) from colic, so be aware of how these healing wounds are affecting your interactions with your child. My daughter’s colic had a HUGE effect on how I felt drawn to parent her, even after the colic passed. I only realized this because I could compare my interactions with her to my interactions with my first child, a boy who almost never cried. When he cried, I had been moved by a deep sense of urgency to attend to him promptly and with empathy. But I became inured to my daughter’s tears, I just didn’t believe her crying meant as much. I had to make a conscious effort to give her the same degree of attentiveness I had bestowed upon my son. I would remind myself that in her early months she had had a condition that actually caused her pain. Her tears meant just as much as my son’s, even though they had been far more abundant. Eventually, good “maternal responsiveness” towards my daughter became second nature. But I had to fake it 'til I made it.

Today my daughter is a well-tempered, well-mannered, tough toddler with advanced cognitive development. When she falls off her hobby-horse, she gets back on. She reads numbers. She is gregarious and caring, and says “thank you so much!” Now it’s so obvious to me that when this sweet little thing cries, it’s because she needs me. Colic casts a curse that breaks our attunement with our child, but if we do the work, we can break its hold on us.
 

Need a colic detective?

It's one thing to know the possible causes of colic, but another to figure out which applies to your baby. Based on the research and my own personal experience with two different types of colic (physical and emotional), I offer colic coaching in which I help parents deduce the cause of their infant’s colic, identify appropriate remedies, and establish rituals that will help them avoid the long-term challenges associated with colic. These evidence-based strategies help families make it through the colic period with healthier perceptions of themselves and their infant, and establish a better postpartum experience.

Are you a colic veteran? What were your baby's crying patterns? How do you feel about the "Rule of Threes?" Did anything work for you that I didn't mention? Please share your experiences with me. I'd love to learn more through your personal encounters with colic.

REFERENCES

(1) Wessel, Morris A, John C Cobb, Edith B Jackson, George S Harris Jr, Ann C Detwiler. “Paroxysmal Fussing in Infancy, Sometimes Called ‘Colic.’” Pediatrics 14.5 (1954): 421-434.

(2) Lothe, Lasse, Tor Lindberg, Irene Jakobsson. “Cow’s Milk Formula as a Cause of Infant Colic: A Double-Blind Study.” Pediatrics 70.1 (1982): 7-10.

(3) Taubman, Bruce. “Prental Counseling Compared with Elimination of Cow’s Milk or Soy Milk Protein for the Treatment of Infant Colic Syndrome: A Randomized Trial.” Pediatrics 81.6 (1988): 756-761.

(4) Iacono G, Carroccio A, Montalto G. “Severe infantile colic and food intolerance: a long-term prospective study.” Journal of Pediatric Gastroenterology and Nutrition 12.3 (1991): 332–335.

(5) Living and Loving [Web log post]. (2017, May 16). Colicky Babies at Higher Risk for Shaken Baby Syndrome. Retrieved April 2 2018 from https://www.livingandloving.co.za/baby-blog/colicky-babies-higher-risk-shaken-baby-syndrome.

(6) Seifritz, Erich, Fabrizio Esposito, John G. Neuhoff, Andreas Luthi, Henrietta Mustovic, Gerhard Dammann, Ulrich von Bardeleben, Ernst W Radue, Sossio Cirillo, Gioacchino Tedeschi, Francesco Di Salle. “Differential Sex-Independent Amygdala Response to Infant Crying and Laughing in Parents versus Nonparents.” Society of Biological Psychiatry 54 (2003): 1367-1375.

(7) Boukydis, CF Zachariah, Robert L Burgess. “Adult Physiological Response to Infant Cries: Effects of Temperament of Infant, Parental Status, and Gender.” Society for Research in Child Development 53 (1982): 1291-1298.

(8) Blumenthal, Ivan. “The Gripe Water Story.” Journal of the Royal Society of Medicine 93 (2000): 172-174. 

(9) Garrison, Michelle M, Dimitri A Christakis. “Early Childhood: Colic, Child Development, and Poisoning Prevention.” Pediatrics 106.1 (2000): 184-190.

(10) Savino, F. “Focus on Infantile Colic.” Acta Paediatrica 96.9 (2007): 1259-1264.

(11) Rautava, Päivi, Liisa Lehtonen, Hans Helenius, Matti Sillanpää. “Infantile Colic: Child and Family Three Years Later.” Pediatrics 96.1 (1995): 43-47.

(12) Wake, Melissa, Elise Morton-Allen, Zeffie Poulakis, Harriet Hiscock, Susan Gallagher, Frank Oberklaid. “Prevalence, Stability, and Outcomes of Cry-Fuss and Sleep Problems in the First 2 Years of Life: A Prospective Community-Based Study.” Pediatrics 117.13 (2006): 836-842.

(13) Hemmi, Mirja Helen, Dieter Wolke, Silvia Schneider. “Associations between problems with crying, sleeping, and/or feeding in infancy and long-term behavioural outcomes in childhood: a meta-analysis.” Archives of Disease in Childhood (2011). doi:10.1136/adc.2010.191312.

(14) Savino, Francesco, Emanuele Castagno, Roberta Bretto, Cristina Brondello, Elisabetta Palumeri, Roberto Oggero. “A Prospective 10-Year Study on Children Who Had Severe Infantile Colic: Colicky Infants 10 Years Later.” Acta Paediatrica 94.449 (2007): 129-132.

(15) Rao, MR, RA Brenner, EF Schisterman, T Vik, JL Mills. “Long Term Cognitive Development in Children with Prolonged Crying.” Archives of Disease in Childhood 89 (2004): 989-992.

(16) Dieter, Wolke, Gabriele Schmid, Andrea Schreier, Renate Meyer. “Crying and Feeding Problems in Infancy and Cognitive Outcome in Preschool Children Born at Risk: A Prospective Population Study.” Journal of Developmental & Behavioral Pediatrics 30.3 (2009): 226-238.

(17) Baby Center [Web log post]. Colic: What Is It? Retrieved April 2 2018 from https://www.babycenter.com/0_colic-what-is-it_77.bc

(18) Barr, RG, RB Trent, J Cross. “Age-related incidence curve of hospitalized Shakenn Baby Syndrome cases: Convergent data for crying as a trigger to shaking.” Child Abuse and Neglect 30.1 (2006): 7-16.

(19) ColicHelp.com [Web log post]. N.d. What is Shaken Baby Syndrome? Retrieved April 2 2018 from http://www.colichelp.com/shakenbabysyndrome.html.

(20) Canivet, C, I Jakobsson, B Hagander. “Infantile colic. Follow-up at four years of age: Still more ‘emotional.’” Acta Paediatrica (2007): https://doi.org/10.1111/j.1651-2227.2000.tb01179.x

(21) Fouts, Hillary N, Michael E Lamb, Barry S Hewlett. “Infant crying in hunter-gatherer cultures.” Behavioral and Brain Sciences 27.4 (2004): 462-463.

(22) Akman, I, K Kuscu, N Ozdemir, Z Yurdakul, M solakoglu, L Orhan, A Karabekiroglu, E Ozek. “Mothers’ postpartum psychological adjustment and infantile colic.” Archives of Disease in Childhood 91.5 (2006): 417-419.

(23) Murray, Lynne, Peter J Cooper. “The impact of postpartum depression on child development.” Internal Review of Psychiatry 8.1 (1996): 55-63.

(24) Cummings, Edward Mark, Patrick T Davies. “Maternal Depression and Child Development.” Journal of Child Psychology and Psychiatry 35.1 (2006): 73-122.

(25) Erickson, Martha Farrell, L Alan Sroufe, Byron Egeland. “The Relationship between Quality of Attachment and Behavior Problems in Preschool in a High-Risk Sample.” Monographs of the Society for Research in Child Development 50.1/2 (1985): 147-166.

(26) Murray, Lynne, Agnese Fiori-Cowley, Richard Hooper, Peter Cooper. “The impact of postnatal depression and associated adversity on early mother-infant interactions and later infant outcomes.” Child Development 67.5 (1996): 2515-2526.

(27) Cherry, Kendra. (2018). Overview of Attachment in Childhood. Retrieved from VeryWell Mind on April 2 2018 from https://www.verywellmind.com/what-is-attachment-2794822.

(28) Vik, Torstein, Viet Grote, Joauqin Escribano, Jerzy Socha, Elvira Verduci, Michaela Fritsch, Clotilde Carlier, Rudiger von Kries, Berthold Koletzko. “Infantile colic, prolonged crying and maternal postnatal depression.” Acta Paediatrica 98.8 (2009): 1344-1348.

(29) Levitzky, Susan, Robyn Cooper. “Infant colic syndrome-maternal fantasies of aggression and infanticide.” Clinical Pediatrics 39.7 (2000): https://doi.org/10.1177/000992280003900703

(30) Raiha, H, L Lehtonen, V Huhtala, K Saleva, H Korvenranta. “Excessively crying infant in the family: mother-infant, father-infant and mother-father interaction.” Child: Care, Health, Development 28.5 (2002): 419-429.

(31) Taubman, Bruce. “Clinical Trial of the Treatment of Colic by Modification of Parent-Infant Interaction.” Pediatrics 74.6 (1984): 998-1003.

(32) Canivet, Catarina, Per-Olof Ostergren, Anne-Sofie Rosen, Irene L Jakobsson, Barbro M Hagander. “Infantile colic and the role of trait anxiety during pregnancy in relation to psychosocial and socioeconomic factors.” Scandinavian Journal of Public Health 33.1 (2005): 26-34.

(33) Circle of Security International. (2014, Dec. 1). Circle of Security Animation [video file]. YouTube. Retrieved on April 2, 2018 from YouTube https://www.youtube.com/watch?v=1wpz8m0BFM8

(34) Konner, Melvin, Carol Worthman. “Nursing Frequency, Gonadal Function, and Birth Spacing among !Kung Hunter-Gatherers.” Science 207.4432 (1980): 788-791.

(35) Garrison, Michelle M, Dimitri A Christakis. “Early Childhood: Colic, Child Development, and Poisoning Prevention: A Systematic Review of Treatments for Infant Colic.”  Pediatrics 106.1 (2000): 184-190.

(36) Savino, Francesco. “Focus on infantile colic.” Acta Paediatrica (2007): DOI:10.1111/j.1651-2227.2007.00428.x

(37) Sung, Valerie, Harriet Hiscock, Mimi L K Tang, Fiona K Mensah, Monica L Nation, Catherine Satzke, Ralf G Heine, Amanda Stock, Ronald G Barr, Melissa Wake. “Treating infant colic with the probiotic Lactobacillus reuteri: double blind, placebo controlled randomized trial. BMJ 348 (2014): https://doi.org/10.1136/bmj.g2107 

(38) Søndergaard, C, J Olsen, E Friis-Haschè, M Dirdal, N Thrane, HT Sørensen. “Psychosocial distress during pregnancy and the risk of infantile colic: a follow-up study.” Acta Paediatrica 92.7 (2003): 811-816.

(39) Field, Tiffany, Muguel Diego, Maria Hernandez-Reif, Barbara Figueiredo, Osvelia Deeds, Angela Ascencio, Saul Schanberg, Cynthia Kuhn. “Comorbid Depression and anxiety effects on pregnancy and neonatal outcome.” Infant Behavior and Development 33.1 (2010): doi 10.1016/j.infbeh.2009.10.004

(40) Wadhwa, Pathk D, Christine Dunkel-Schetter, Aleksandra Chjcz-Demet, Manuel Porto, Curt A. Sandman. “Prenatal Psychosocial Factors and the Neuroendocrine Axis in Human Pregnancy.” Psychosomatic Medicine 58 (1996): 432-446.

(41) Kennaway, DJ. “Programming of the fetal suprachiasmatic nucleus and subsequent adult rhythmicity.” Trends in Endocrinology and Metabolism 13.9 (2002): 398-402.

(42) Rautava, Paivi, Hans Helenius, Liisa Lehtonen. “Psychosocial predisposing factors for infantile colic.” 307 (1993): 600-604.

(43) Sondergaard, C, J Olsen, E Friis-Hasche, M Dirdal, N Thrane, HT Sorensen. “Psychosocial distress during pregnancy and the risk of infantile colic: a follow-up study.” Acta Paediatrics 92.7 (2003): 811-816.

(44) Oberlander, Tim F, Joanne Weinberg, Michael Papsdorf, Ruth Grunau, Shaila Misri, Angela M Devlin. “Prenatal exposure to maternal depression, neonatal methylation of human glucocorticoid receptor gene (NR3C1) and infant cortisol stress responses.” Epigenetics 3.2 (2008): 97-106.

(45) Palagini, L, K Biber, D Riemann. “The genetics of insomnia—Evidence for epigenetic mechanisms?” Sleep Medicine Reviews 18.3 (2014): 225-235.

(46) White, Barbara Prudhomme, Megan R Gunnar, Mary C Larson, Bonny Donzella, Ronald G Barr. “Behavioral and Physiological Responsivity, Sleep, and Patterns of Daily Cortisol Production in Infants with and without Colic.” Child Development 71.4 (2000): 862-877.

(47) Weissbluth, L, M Weissbluth. “Infant colic: The effect of serotonin and melatonin circadian rhythms on the intestinal smooth muscle.” Medical Hypotheses 39.2 (1992): 164-167.

(48) Bell, Silvia M, Mary D Salter Ainsworth. “Infant Crying and Maternal Responsiveness.” Child Development 43 (1972): 1171-1190.

(49) Neal, Heather. N.d. The Unspoken Long-Term Effect of Colic. Retrieved on April 2, 2018 from Babble https://www.babble.com/parenting/the-unspoken-long-term-effect-of-colic-post-colic-stress-syndrome/