Growth Curve | Science News

Be a Champion for Science

Get your subscription to

Science News when you join.

Growth Curve

The inexact science of raising kids

Laura Sanders

Growth Curve


Growth Curve

Birth may not be a major microbe delivery event for babies

Study finds no big differences in microbiomes of babies born vaginally or by C-section

newborn baby

Whether a baby is born vaginally or by C-section may not be a major determinant for babies’ microbiomes, a new study suggests.

Sponsor Message

Babies are born germy, and that’s a good thing. Our microbiomes — the microbes that live on and in us — are gaining cred as tiny but powerful keepers of our health.

As microbes gain scientific stature, some scientists are trying to answer questions about how and when those germs first show up on babies. Birth itself may be an important microbe-delivery event, some researchers suspect. A trip through the birth canal can coat a baby with bacteria from his mother. A C-section, some evidence suggests, might introduce different bacteria, at least right after birth.

That difference forms the basis of the practice of vaginal seeding, which involves wiping vaginal fluids onto a baby born by C-section to introduce microbes the baby would have encountered in a vaginal birth.

Even while some parents are asking for the procedure, there’s dissent in the ranks of research about its benefits. Scientists don’t agree yet on how — or even whether — type of birth affects the microbiome. “It’s murky,” says obstetrician and maternal-fetal medicine specialist Kjersti Aagaard of the Baylor College of Medicine in Houston. Existing studies don’t clearly distinguish the effects of the C-section itself from those of certain diseases or conditions that can make a C-section more likely, such as maternal diabetes or obesity, she says. Other issues, like whether a baby received antibiotics or is breastfed, also muddy the waters. “You are left saying, ‘Wait a minute. Is it the surgery or not the surgery? What’s going on here?’” Aagaard says.

In a search for clarity, Aagaard and her colleagues surveyed the microbiomes of 81 pregnant women. Later on, the researchers added a second group of 82 women, whose microbiomes were assessed at the birth of their children.

Just after birth, babies who had been delivered by C-section had different mouth, nose and skin microbiomes than babies born vaginally. One possible explanation is that these babies are handled differently just after birth, Aagaard says. The microbiomes of the babies’ meconium, or stool, appeared to be similar, regardless of how the babies were born.

But between four and six weeks later, these C-section/vaginal birth differences on the mouth, nose and skin were largely gone, Aagaard says. The microbes living in and on the babies born by C-section and those born vaginally were nearly indistinguishable, the researchers reported online January 23 in Nature Medicine.

Depending on where they lived, the populations of microbes had already taken on distinct identities by about a month after birth, the researchers found. Communities of nose-dwelling microbes were easy to distinguish from those living in the gut, for instance. These regional differences are signs of surprising microbial maturity, Aagaard says. “Postnatal microbiomes start looking like adults a little sooner than we may have appreciated,” she says.

The results raise an interesting question: If the type of birth isn’t one of the main shapers of microbiomes, then how and when do microbes get into babies? It’s possible that microbes from mothers slip into fetuses during pregnancy — a plausible idea, given some earlier results. Genetically tagged bacteria fed to pregnant mice showed up in their fetuses’ guts a day before the predicted due date, a result that suggests the bacteria traveled from mother to fetus. And Aagaard and colleagues have found evidence of microbes in the placenta of human mothers. They are now studying whether microbes, or perhaps pieces of them, move through the placenta from mother to baby. If that turns out to be the case, then babies meet their microbes, for better or worse, well before their birthday.

Human Development,, Health

Little jet-setters get jet lag too

By Laura Sanders 1:00pm, February 6, 2017
Help young children fight jet lag with a few simple steps.
Health,, Human Development

A ban on screens in bedrooms may save kids’ sleep

By Laura Sanders 4:35pm, January 23, 2017
Screens are associated with worse sleep in kids, and not just because of their lights and noises.
Health

Though complex, new peanut allergy guidelines are based on science

By Meghan Rosen 1:29pm, January 13, 2017
Unlike some past recommendations, new guidelines state that introducing babies to peanut-containing foods early is generally OK, with certain caveats.
Human Development,, Health,, Neuroscience

Motherhood might actually improve memory

By Laura Sanders 11:21am, December 21, 2016
Having a baby changes all sorts of things, including a mother’s brain.
Human Development

Database provides a rare peek at a human embryo’s first weeks

By Meghan Rosen 9:00am, December 6, 2016
A new 3-D atlas charts the growth of each and every organ in the developing human embryo, from the heart to the gut to the brain.
Human Development,, Neuroscience

What not to do when your kid tells a lie

By Laura Sanders 9:00am, November 11, 2016
We teach children that lying is naughty, but it’s actually a sign of good brain development.
Human Development,, Health,, Neuroscience

Screen time guidelines for kids give parents the controls

By Laura Sanders 6:00am, October 23, 2016
New recommendations for children’s media use are more nuanced than earlier guidelines, a change that reflects the shifting technology landscape.
Human Development

Baby-led weaning is safe, if done right

By Laura Sanders 9:00am, October 14, 2016
Babies who fed themselves solid foods, called baby-led weaning, were no more likely to choke than spoon-fed babies, a new study finds.
Health

Don’t cocoon a kid who has a concussion

By Laura Sanders 3:00pm, September 29, 2016
Parents should fight the urge to limit kids’ activities after a concussion.
Health

Maybe you don’t need to burp your baby

By Laura Sanders 9:26am, September 15, 2016
Everybody does it. But burping babies after a meal may not cut down on crying or spit-ups, a study suggests.
Subscribe to RSS - Growth Curve