First hour of life for newborns: a timeline

Photo by Mikaela Wapman

Photo by Mikaela Wapman

Laura Sanders of Science News recently published a post on a Timeline of a Baby’s First Hour.

In the post, she stumbles upon a 2011 study from Sweden regarding observations of 28 of “the most mysterious creatures on the planet: brand-spanking-new humans.”

Sanders goes on,

Videos of babies in their first hour of life gave the researchers an unprecedented view of how newborns instinctually behave, when left to their own devices and nestled skin-to-skin on their mothers’ chests. I found the results, published in January 2011 in Acta Paediatrica, just as fascinating as the Drosophila courtship ritual.

Having supported a fair number of births in the hospital, I have witnessed many of the instincts of the newborn to cry, nurse, and sleep. Sometimes, routine tests or complications in birth interrupt the newborn’s instinctive inclinations and the maternal / infant initiation, as the hospital team performs the necessary evaluations, perfunctory tests (birth weight, length, head measurements, immunizations… the list goes on and on).

In uncomplicated, low-intervention births, new mothers are able to rest with their newborns on their chest and relish in the unique, indescribable joy of skin-to-skin. It is during these moments that the researchers from Sweden noted some key milestones in the first hour and 10 minutes of a newborn’s life, presented in median minutes:

Minute 0: Babies wail a robust, angry birth cry that helps wake up the lungs.

Minute 2: After all that wailing, babies spend less than a minute relaxing, holding perfectly still on their mothers’ chests. The authors speculate that this silent, still break might have evolved to keep babies hidden from predators.

Minute 2.5: As they start to wake up, newborns open their eyes for the first time. Babies gradually start moving their heads and mouths.

Minute 8: Babies become even more active, keeping their eyes open for five minutes or longer at a time. During this active phase, newborns seem to grow interested in eating, looking at their mothers’ faces and breasts, making sweet little “hungry” noises and moving their hands toward their mouths.

Minute 18: That was exhausting. Time for another rest.

Minute 36: Recharged newborns really kick it into high gear and begin scooting toward their mothers’ breasts, relying heavily on a sense of smell to navigate.

Minute 62: Babies nurse, most likely getting small amounts of colostrum, a pre-milk substance packed with protein and immune molecules. This early suckling stimulates the breasts to make milk and also helps mom’s uterus contract back to its pre-pregnancy size.

Minute 70: Babies fall asleep for a well-deserved break.

There you have it: the first seventy minutes of a newborn’s life, as described by science. Of course, these minute markers are median numbers drawn from a small number of newborns (n=28), and even the time tables of the babies included in the study varied substantially. Any single baby’s behavior might fall well outside of these time points.

These quantitative observations are helpful with respect to the introduction and recent emphasis that most hospitals are placing on “baby friendly” practices, designed to encourage breastfeeding and also happen to support the bond between mom and baby.

Photo by Mikaela Wapman

Photo by Mikaela Wapman

“Baby friendly” practices, as outlined by Baby-Friendly USA, state that “health care systems should ensure that maternity care practices provide education and counseling on breastfeeding. Hospitals should become more “baby-friendly,” by taking steps like those recommended by the UNICEF/WHO’s Baby-Friendly Hospital Initiative.” Initiatives to improve breastfeeding rates include forgoing formula and pacifiers, allow the mom and baby to stay together (rather than baby in nursery), and provide hospital staff to instruct and support new moms with breastfeeding.

Sanders refers to another observational study:

In the first hour of birth, babies whose chins touched the underside of their mothers’ breasts were more likely to successfully suckle than babies who didn’t do a chin-brush. These sorts of studies, which rely on carefully watching a newborn, are beginning to paint a more complete picture of what newborns might need in the moments after birth. And that understanding might ultimately be useful to the adults who want to ease the introduction of this new little person to the world.

Observations from these studies regarding the instinctive newborn behaviors – without interference from anyone – might help healthcare providers come up with better ways to encourage breastfeeding, and cut down on some of the routine tests that might be best delayed until the third (or fourth, fifth, or sixth) hour of the baby’s life.

You can read the whole article here. Via Science News.


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Why the Long, Difficult Birth for Humans?

Labor for first time moms averages somewhere between 10 – 20 hours. Among other Great Apes, such as Chimpanzees, labor takes on average two hours. In addition to the time in labor, human labor is described as extremely difficult compared to other primates.

What characteristics contribute to such disparate childbirths in humans and other primates?

1. The Obstetric Dilemma

The most significant tradeoffs in human evolution are evidenced at the time of birth: efficient bipedal locomotion promotes a relatively narrow pelvis, while delivering relatively large-brained babies selects for a broad pelvis. In other words, the narrow pelvic opening that is good for efficient upright walking is not so good for the delivery of large-brained humans.

The interaction of these features in our evolutionary history has shaped a female pelvis that reflects a compromise in these selective pressures: the constraints on the human pelvis due to walking on two legs, combined with the exceptionally large brains of human babies make human birth especially long and painful.

2. Bipedalism Promotes a Narrow Pelvis

Humans are the only living mammal to walk on two legs, and bipedalism requires narrow, short, squat, and basin shaped pelvic anatomies. In contrast, quadrupedal animals (like our closest relatives, chimpanzees) have pelvises that are long and two dimensional in appearance. Compare image A (the pelvis of a chimpanzee) to image C (the pelvis of a human female).

Comparison of pelves from (A) Pan, (B) Australopithecus, (C) Human female, and (D) Human male (from Lovejoy, 2005, figure 5).

Comparison of pelves from (A) Pan, (B) Australopithecus, (C) Human female, and (D) Human male (from Lovejoy, 2005, figure 5).

Notice how long the chimpanzee (image A) pelvis is compared to the squat pelvis of a human female (image C)? That humans walk on two legs is one explanation for the pronounced differences between humans and chimpanzees.

3. Big Brains and Birth

One important characteristic of primates as a group is a high encephalization quotient, or a large head and brain relative to body size. For most primates, this means that neonates at birth have heads that are close to the size of the maternal birth canal through which they must pass, making birth far from easy.

From Rosenberg and Trevathan (2002); based on Shultz (1949).

From Rosenberg and Trevathan (2002); based on Shultz (1949).

The image above describes the relationship of the maternal pelvic inlet (outer white ovals) and size of the baby’s head (dark solid ovals).

Think of a hard boiled egg. For gorillas and chimpanzees, the baby’s head is the size of the yolk, while the mother’s pelvic opening is the size of the egg white. Though baby must pass through the muscles and tissue of the birth canal, there is no bony resistance from the mother’s pelvis. For humans, imagine the hard boiled egg as the shape of the pelvic opening, and a golf ball as the baby’s head.

4. Passage through the Birth Canal

It’s not just the tight squeeze that makes birth difficult – the human birth canal isn’t a constant shape in cross-section. Thanks to bipedalism, the the birth canal is twisted in the middle, while the birth canal is described as a “relatively straight tube” for quadrupedal primates. A monkey baby has a tight squeeze through his mother’s pelvis, however her birth is significantly less difficult than a human baby’s. This is because, unlike the complicated cross-sectional area of the human birth canal, a monkey’s birth canal maintains the same cross-sectional dimensions from front to back.

Image by Karen R. Rosenberg and Wenda R. Trevathan

Image by Karen R. Rosenberg and Wenda R. Trevathan

As a human baby makes her way down the birth canal, she enters the birth canal at it’s widest side-to-side, relative to the mother’s body. But midway through, the orientation of the birth canal shifts 90 degrees, and the baby must now navigate a series of twists and turns so that her largest dimensions – the head and shoulders – are aligned with the largest areas of the birth canal.

The baby must rotate through the changing dimensions of the birth canal twice in order to navigate and pass through the differing pelvic dimensions through the birth canal’s entrance and exit. Our unique mechanism of birth is one of the distinguishing features of human birth, and adds an additional source of difficulty for so many mothers and babies.

5. Differing Degrees of Cervical Dilation

Among primates, human babies have exceptionally big brains. Because of this, the female cervix must dilate three times as much as other primates in order to deliver the big-brained, broad shouldered baby.

Image via Dr. Cheryl Knott

Image from Dr. Cheryl Knott via

Chimpanzee mothers must dilate around 3.3 centimeters before they’re able to give birth. Human mothers must dilate 10 centimeters before they’re able to deliver. The extra 6.6 centimeters of dilation takes significantly more time, but later stages of dilation are also experienced as significantly more painful. As described in the Mayo Clinic, the early stages of labor (0 – approximately 4cmaren’t always experienced as particularly uncomfortable, and certainly don’t require the same degree of attention as later stages of labor. Later stages of dilation (around 8, 9, 10 centimeters) leading up to transition and delivery are when women experience the most pain.

In Sum: the Obstetric Dilemma

Researchers eloquently describe the interaction of demands as a “tug of war” exerted on the maternal pelvis, which makes human birth significantly more risky than birth in other primates and mammals. Others have described this tradeoff as a scar of human evolutionary history, or the obstetric dilemma.

The Good News: Delivering with Company

Unlike most primates who seek solitude during parturition, virtually all women cross-culturally seek out assistance during birth from relatives, doulas, obstetricians, midwives, and other supports. While there are stories of women who had successful solitary births, studies of childbirth across cultures find that these stories are exceptional. Across cultures, women seek out both physical and emotional assistance in labor and delivery.

If you’re pregnant, consider giving birth with continuous emotional support: from a partner, family member, friend, or doula. A woman’s desire to be surrounded by familiar “others” has deep roots in our human lineage, is associated with fewer birthing complications.


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