Menus Subscribe Search

Follow us


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

December 20 • 10:28 AM

Flare-Ups

Are my emotions making me ill?


December 19 • 4:00 PM

How a Drug Policy Reform Organization Thinks of the Children

This valuable, newly updated resource for parents is based in the real world.


December 19 • 2:00 PM

Where Did the Ouija Board Come From?

It wasn’t just a toy.


December 19 • 12:00 PM

Social Scientists Can Do More to Eradicate Racial Oppression

Using our knowledge of social systems, all social scientists—black or white, race scholar or not—have an opportunity to challenge white privilege.


December 19 • 10:17 AM

How Scientists Contribute to Bad Science Reporting

By not taking university press officers and research press releases seriously, scientists are often complicit in the media falsehoods they so often deride.


December 19 • 10:00 AM

Pentecostalism in West Africa: A Boon or Barrier to Disease?

How has Ghana stayed Ebola-free despite being at high risk for infection? A look at their American-style Pentecostalism, a religion that threatens to do more harm than good.


December 19 • 8:00 AM

Don’t Text and Drive—Especially If You’re Old

A new study shows that texting while driving becomes even more dangerous with age.


December 19 • 6:12 AM

All That ‘Call of Duty’ With Your Friends Has Not Made You a More Violent Person

But all that solo Call of Duty has.


December 19 • 4:00 AM

Food for Thought: WIC Works

New research finds participation in the federal WIC program, which subsidizes healthy foods for young children, is linked with stronger cognitive development and higher test scores.


December 18 • 4:00 PM

How I Navigated Life as a Newly Sober Mom

Saying “no” to my kids was harder than saying “no” to alcohol. But for their sake and mine, I had to learn to put myself first sometimes.


December 18 • 2:00 PM

Women in Apocalyptic Fiction Shaving Their Armpits

Because our interest in realism apparently only goes so far.


December 18 • 12:00 PM

The Paradox of Choice, 10 Years Later

Paul Hiebert talks to psychologist Barry Schwartz about how modern trends—social media, FOMO, customer review sites—fit in with arguments he made a decade ago in his highly influential book, The Paradox of Choice: Why More Is Less.


December 18 • 10:00 AM

What It’s Like to Spend a Few Hours in the Church of Scientology

Wrestling with thetans, attempting to unlock a memory bank, and a personality test seemingly aimed at people with depression. This is Scientology’s “dissemination drill” for potential new members.


December 18 • 8:00 AM

Gendering #BlackLivesMatter: A Feminist Perspective

Black men are stereotyped as violent, while black women are rendered invisible. Here’s why the gendering of black lives matters.


December 18 • 7:06 AM

Apparently You Can Bring Your Religion to Work

New research says offices that encourage talk of religion actually make for happier workplaces.


December 18 • 6:00 AM

The Very Weak and Complicated Links Between Mental Illness and Gun Violence

Vanderbilt University’s Jonathan Metzl and Kenneth MacLeish address our anxieties and correct our assumptions.


December 18 • 4:00 AM

Should Movies Be Rated RD for Reckless Driving?

A new study finds a link between watching films featuring reckless driving and engaging in similar behavior years later.


December 17 • 4:00 PM

How to Run a Drug Dealing Network in Prison

People tend not to hear about the prison drug dealing operations that succeed. Substance.com asks a veteran of the game to explain his system.


December 17 • 2:00 PM

Gender Segregation of Toys Is on the Rise

Charting the use of “toys for boys” and “toys for girls” in American English.


December 17 • 12:41 PM

Why the College Football Playoff Is Terrible But Better Than Before

The sample size is still embarrassingly small, but at least there’s less room for the availability cascade.


December 17 • 11:06 AM

Canadian Kids Have a Serious Smoking Problem

Bootleg cigarette sales could be leading Canadian teens to more serious drugs, a recent study finds.


December 17 • 10:37 AM

A Public Lynching in Sproul Plaza

When photographs of lynching victims showed up on a hallowed site of democracy in action, a provocation was issued—but to whom, by whom, and why?


December 17 • 8:00 AM

What Was the Job?

This was the year the job broke, the year we accepted a re-interpretation of its fundamental bargain and bought in to the push to get us to all work for ourselves rather than each other.


December 17 • 6:00 AM

White Kids Will Be Kids

Even the “good” kids—bound for college, upwardly mobile—sometimes break the law. The difference? They don’t have much to fear. A professor of race and social movements reflects on her teenage years and faces some uncomfortable realities.



Follow us


Don’t Text and Drive—Especially If You’re Old

A new study shows that texting while driving becomes even more dangerous with age.

Apparently You Can Bring Your Religion to Work

New research says offices that encourage talk of religion actually make for happier workplaces.

Canadian Kids Have a Serious Smoking Problem

Bootleg cigarette sales could be leading Canadian teens to more serious drugs, a recent study finds.

The Hidden Psychology of the Home Ref

That old myth of home field bias isn’t a myth at all; it’s a statistical fact.

The Big One

One in two United States senators and two in five House members who left office between 1998 and 2004 became lobbyists. November/December 2014

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