Menus Subscribe Search

Don’t Mess With Breastfeeding Women

• August 30, 2011 • 8:00 AM

Newly published research suggests lactation increases aggression.

Earlier this year, we reported that breast-feeding women are widely viewed as less competent. Newly published research suggests it would be unwise to share that unflattering opinion with them.

According to a team led by UCLA health psychologist Jennifer Hahn-Holbrook, lactating women display higher levels of aggression than both non-mothers and their bottle-feeding counterparts. What’s more, their blood pressure stays low even as their combativeness increases, which may be nature’s way of allowing new mothers to calmly but effectively deal with potential threats.

Writing in the journal Psychological Science, Hahn-Holbrook and her colleagues describe an experiment featuring 33 mothers with infants between 3 and 6 months old, and 18 women who had never given birth.

Seventeen of the mothers exclusively breast-fed their baby; the other 16 used formula either some or all of the time. Those who sometimes breast-fed were asked to abstain from the practice for at least 12 hours prior to the experiment.

The women participated in a computer game that measured their reaction time to threatening images. Each was told she would be competing with another participant, whom she was introduced to at the outset of the experiment.

To increase the participants’ irritation level, their purported competitors — who were actually female research associates — acted rude at this initial meeting. Specifically, they “were trained to ignore participants, chew gum and check their cell phones for 20 seconds while the experimenter spoke during the training period,” the researchers write.

Participants were told that when they won a round — that is, when they spotted and responded to the threatening stimuli more quickly than their competitor — they could “choose the volume and duration of an aversive sound burst administered to the loser.” They selected the intensity level of the unpleasant noise before each round, and the length of time it would last (up to five seconds) each time they won.

The mothers were separated from their babies during the experiment — except for a break in the middle. During this time, exclusively breast-feeding mothers engaged in breast feeding; the other mothers bottle-fed their infants; and the non-mothers simply relaxed. All had their blood pressure measured at various times before and after this interlude.

Mothers who exclusively breast-fed their infants “were almost twice as aggressive” as the other participants, inflicting louder and longer bursts of noise on their opponents. In contrast, “formula-feeding mothers did not demonstrate more aggressive behavior than non-mothers,” the researchers report.

Furthermore, “Exclusively breast-feeding mothers had lower blood pressure during the aggressive encounters,” the researchers write. This suggests lactation reduces “otherwise prohibitive levels of maternal fear,” allowing mothers to aggressively respond to any perceived threat.

Hahn-Holbrook and her colleagues don’t believe lactation “engenders hostile behavior indiscriminately.” Research on other mammals suggests breast-feeding is “likely to boost aggression primarily in contexts in which either the mother or her offspring are in jeopardy,” they write.

So, at a time when relatively few American mothers breast-feed, here’s another advantage this natural practice provides: The ability to remain calm while aggressively responding to threats.

Sign up for the free Miller-McCune.com e-newsletter.

“Like” Miller-McCune on Facebook.

Follow Miller-McCune on Twitter.

Add Miller-McCune.com news to your site.

Subscribe to Miller-McCune

Tom Jacobs
Staff writer Tom Jacobs is a veteran journalist with more than 20 years experience at daily newspapers. He has served as a staff writer for The Los Angeles Daily News and the Santa Barbara News-Press. His work has also appeared in The Los Angeles Times, Chicago Tribune, and Ventura County Star.

More From Tom Jacobs

A weekly roundup of the best of Pacific Standard and PSmag.com, delivered straight to your inbox.

Recent Posts

July 30 • 4:00 AM

The Declining Wage Gap for Gay Men

New research finds gay men in America are rapidly catching up with straight married men in terms of wages.


July 30 • 2:00 AM

LeBron James Migration: Big Chef Seeking Small Pond

The King’s return to Cleveland is a symbol for the dramatic shift in domestic as well as international migration.


July 29 • 4:00 PM

Are Children Seeking Refuge Turning More Americans Against Undocumented Immigrants?

A look at Pew Research Center survey data collected in February and July of this year.


July 29 • 2:00 PM

Under Water: The EPA’s Ongoing Struggle to Combat Pollution

Frustration and inaction color efforts to enforce the Clean Water Act.


July 29 • 12:40 PM

America’s Streams Are Awash With Pesticides Banned in Europe

You may have never heard of clothianidin, but it’s probably in your local river.


July 29 • 12:00 PM

Mining Your Genetic Data for Profit: The Dark Side of Biobanking

One woman’s personal story raises deep questions about the stark limits of current controls in a nascent industry at the very edge of the frontier of humans and technology.


July 29 • 11:23 AM

Where Should You Go to College?


July 29 • 10:29 AM

How Textbooks Have Changed the Face of War

War is more personal, less glorious, and more hellish in modern textbooks than in the past. But there’s still room for improvement.


July 29 • 10:00 AM

The Monolingual American: Why Are Those Outside of the U.S. Encouraging It?

If you are an American trying to learn German in a large German town or city, you will mostly hear English in return, even when you give sprechen your best shot.


July 29 • 8:00 AM

The Elusive Link Between Casinos and Crime

With a study of the impact of Philadelphia’s SugarHouse Casino, a heated debate gets fresh ammunition.


July 29 • 6:00 AM

What Are the Benefits of Locking Yourself in a Tank and Floating in Room-Temperature Saltwater?

After three sessions in an isolation tank, the answer’s still not quite clear.


July 29 • 4:00 AM

Harry Potter and the Battle Against Bigotry

Kids who identify with the hero of J.K. Rowling’s popular fantasy novels hold more open-minded attitudes toward immigrants and gays.


July 29 • 2:00 AM

Geographic Scale and Talent Migration: Washington, D.C.’s New Silver Line

Around the country, suburbs are fighting with the urban core over jobs and employees.


July 28 • 4:00 PM

Border Fences Make Unequal Neighbors and Enforce Social Inequality

What would it look like if you combined Israel, the West Bank, and Gaza, demographically speaking? What about the United States and Guatemala?


July 28 • 2:00 PM

Are Patient Privacy Laws Being Misused to Protect Medical Centers?

A 1996 law known as HIPAA has been cited to scold a mom taking a picture of her son in a hospital, to keep information away from police investigating a possible rape at a nursing home, and to threaten VA whistleblowers.


July 28 • 12:00 PM

Does Internet Addiction Excuse the Death of an Infant?

In Love Child, documentary filmmaker Valerie Veatch explores how virtual worlds encourage us to erase the boundary between digital and real, no matter the consequences.


July 28 • 11:11 AM

NASA Could Build Entire Spacecrafts in Space Using 3-D Printers

This year NASA will experiment with 3-D printing small objects in space. That could mark the beginning of a gravity-free manufacturing revolution.


July 28 • 10:00 AM

Hell Isn’t for Real

You may have seen pictures of the massive crater in Siberia. It unfortunately—or fortunately—does not lead to the netherworld.


July 28 • 8:00 AM

Why Isn’t Obama More Popular?

It takes a while for people to notice that things are going well, particularly when they’ve been bad for so long.


July 28 • 7:45 AM

The Most Popular Ways to Share Good and Bad Personal News

Researchers rank the popularity of all of the different methods we have for telling people about our lives, from Facebook to face-to-face.


July 28 • 6:00 AM

Hams Without Ends and Cats Tied to Trees: How We Create Traditions With Dubious Origins

Does it really matter if the reason for why you give money to newlyweds is based on a skewed version of a story your parents once told you?


July 28 • 4:00 AM

A Belief in ‘Oneness’ Is Equated With Pro-Environment Behavior

New research finds a link between concern for the environment and belief in the concept of universal interconnectedness.


July 25 • 4:00 PM

Flying Blind: The View From 30,000 Feet Puts Everything in Perspective

Next time you find yourself in an airplane, consider keeping your phone turned off and the window open.


July 25 • 2:00 PM

Trophy Scarves: Race, Gender, and the Woman-as-Prop Trope

Social inequality unapologetically laid bare.


July 25 • 1:51 PM

Confusing Population Change With Migration

A lot of population change is baked into a region from migration that happened decades ago.


Follow us


Subscribe Now

America’s Streams Are Awash With Pesticides Banned in Europe

You may have never heard of clothianidin, but it's probably in your local river.

How Textbooks Have Changed the Face of War

War is more personal, less glorious, and more hellish in modern textbooks than in the past. But there’s still room for improvement.

NASA Could Build Entire Spacecrafts in Space Using 3-D Printers

This year NASA will experiment with 3-D printing small objects in space. That could mark the beginning of a gravity-free manufacturing revolution.

The Most Popular Ways to Share Good and Bad Personal News

Researchers rank the popularity of all of the different methods we have for telling people about our lives, from Facebook to face-to-face.

Do Not Tell Your Kids That Eating Vegetables Will Make Them Stronger

Instead, hand them over in silence. Or, market them as the most delicious snack known to mankind.

The Big One

One in two full-time American fast-food workers' families are enrolled in public assistance programs, at a cost of $7 billion per year. July/August 2014

Copyright © 2014 by Pacific Standard and The Miller-McCune Center for Research, Media, and Public Policy. All Rights Reserved.