Dr. Harvey Karp

Are Babies Born Too Early?

Explaining the “Missing Fourth Trimester” Theory of Colic

Dr. Harvey Karp—the name is almost synonymous with a peaceful, happy baby. In his book, “The Happiest Baby on the Block,” pediatrician Dr. Harvey Karp explains his theory on colic and the best way to soothe a crying baby. He believes that babies are born a trimester too early and as a result, cry inconsolably and are labeled “colicky.” He calls this theory the “Missing Fourth Trimester.”

So what does a missing fourth trimester have to do with a colicky baby? Dr. Karp compares newborns to horses. When a horse is born, he’s running that same day. A baby, however, is helpless, and needs someone to take care of him. When a baby turns three months old (the same length as a trimester), he starts to “wake up” and begins to smile, “talk” and roll over. But, due to the size of a baby’s brain when he’s born, it’s physically impossible to carry a fetus for another trimester. A 40 week old fetus has a head circumference of 11 cm, and a fully dilated cervix is 10 cm—one doesn’t need to be a math genius to figure out that a baby wouldn’t be able to be delivered if it stayed in the womb much longer than 40 weeks.

Because fetuses have to be born at around 40 weeks, they miss out on the “fourth trimester” and are therefore, not fully developed to withstand the stresses outside the womb. As a result, babies can become colicky.

Dr. Karp explains that his “Missing Fourth Trimester” theory is compatible with several characteristics of colic:

  • Premature babies and the world around them – it’s not until two weeks after the baby’s original due date that he starts to have an increased awareness of the world around him. This is also the time when a preemie will tend to be colicky (not when he is born, for example, at 28 weeks).
  • Intestinal pain – a newborn seems to have symptoms that make it seem that he is in pain. This could be the result of an immature gastrocolic reflex, which is the trigger to tell the colon to start emptying itself to make room for more food. If he was in the womb longer, this reflux would have a chance to mature.
  • Witching Hour – Newborns normally cry at night, which Dr. Karp believes is the result of accumulated stress throughout the day. The baby is stressed because he no longer is in the womb, experiencing calming rhythmic stimulation.
  • Relaxing and shushing – A baby calms down when he is finally relaxed, and hears the “shhhhhhhh” sound, both of which mimic being in the womb.
  • Some cultures don’t experience colic – It’s the parents in these same cultures which are constantly holding, rocking, and nursing their babies, which also mimics being in the womb.
  • Colic usually stops after a baby is three months of age, which is also when he is “four trimesters old.”
Once born, many babies are able to adapt to the world outside the womb. Some, however, have a hard time adjusting, are stressed, and end up crying inconsolably for hours on end. In other words, they have colic. For this reason, Dr. Karp believes it’s vital to recreate the sounds and relaxation which a newborn experienced inside the womb. This is where Dr. Karp’s 5 S’s come in to play:
  • Swaddling – tightly wrapping your baby, with his arms down by his sides, in a blanket, mimics the tight quarters that he had in the womb before being born. However, the proper swaddling technique is crucial. Orthopedic surgeon Dr. Nicholas P. Clarke cautions parents that hip dysplasia can occur if swaddling is not done correctly.
  • Side or stomach position – when putting a baby to sleep, back is best, but when trying to soothe your baby, holding him on his side or stomach will remind him of being in the womb.
  • Shushing sounds – this is the white noise that a baby hears while in the womb.
  • Swinging – swinging mimics the constant rocking that a baby felt before being born.
  • Sucking – a baby is constantly having his fingers in his mouth in utero. To help relax your baby, they can suck on a breast, finger, and after three weeks of age (to avoid nipple confusion) a pacifier.
Hopefully, with these techniques, you will help soothe your colicky infant and have more of an understanding on why he’s behaving as he is. You can also give your baby Colic Calm. Practice those 5 S’s, administer Colic Calm, and know those three months will be over before you know it.