The Science of Lactation and Fertility: When will I get my period back if I’m breastfeeding?


For many breastfeeding moms, lactational amenorrhea is a pretty darn nice perk. With my firstborn, I was one of the lucky ones—I went an entire year after my baby was born without getting a period thanks to breastfeeding.  It would be an understatement to say I was delighted the entire time.  In fact, I seriously considered adding in some extra pumping after year 1 just to keep that lovely little side effect.

Second baby, I was excitedly anticipating another 2 years period free—yippee!!!  So imagine my surprise when at 7 and a half months postpartum, my period returned.  I was supposed to get a full year—just like last time!

Now, as I understood lactational amenorrhea theory at the time, the loss of fertility during lactation was due to the frequency of suckling or nursing intensity.  According to this theory, the more often you feed the baby, the less likely you are to ovulate.1-2  While this makes sense in many cases, in my own experience it didn’t add up. As I was often home with him, I nursed my second baby much more often than I nursed my first (I was working full time and pumping), but my periods returned more than 5 months sooner.

While researching lactational amenorrhea for a review article with colleagues, I came across a study with an alternate theory called the metabolic load hypothesis. Valeggia and Ellison found that in a group of Toba women in Argentina who had high nursing intensity and high nutritional status they could predict the return of menses by looking at a mother’s energy balance rather than just nursing intensity.3   They were looking at this equation:

Total energy taken in (eating)  –  Total energy used up (breastfeeding, exercise)

 When this equation came out to a positive number (more energy in than energy out), the authors could actually detect a rise in C peptide levels (a marker for insulin) in a women’s urine, and soon after, that woman “got her period back.”

When I think about my situation using this theory, it makes a little more sense.  With my first, although I went back to work full time at 3 months, my job as a graduate student in a cell biology lab was pretty physically active.  Despite sitting down a bit here and there, I was frequently standing up, lifting, walking across the lab to get something and moving my body to conduct my experiments. In addition, I was pumping every 3 hours or so while I was away from my baby.  My energy output was more than my energy input up until the time friends convinced me to stop pumping at work a little after my son was a year old.  Within a month my period had returned.

With my second baby, I worked part time and had a more flexible schedule, allowing me to work at home often and be close by to nurse my son on demand much of the time rather than deal with pumping.  While this situation provided for greater nursing intensity, my energy expenditure was much lower than it had been as a graduate student.  In contrast to the constant movement I experienced working in the lab, as a professor I spent much of my work time sitting and writing on the computer, and sometimes snacking while I was doing that.  Not a good recipe for expending energy!

Given the differences in my activity level while nursing my 2 children, the very different timing I experienced in return of menses starts to make sense.

Although most of us (myself included) generally think about this in terms of the physical signals of menses–getting our periods back— what’s really happening is ovulation.  You may have heard that high performance athletes often stop menstruating when they’re training really intensely?  Scientists believe that intense energy expenditure or lack of food act as a signal to the body that it’s not a good time to reproduce, causing the body to shut down ovulation.  Making and raising babies takes a tremendous amount of resources—not something mom has if she’s starving or expending huge amounts of energy, such as in training for the Olympics.

According to the metabolic load hypothesis, lactational amenorrhea may work much the same way.  Milk making in humans requires an average of 500 extra calories a day, even more than pregnancy.  If mom is exclusively breastfeeding and active, her energy output through activity and lactation is likely to be greater than or equal to her energy input.  If baby starts nursing less, mom becomes less active, or starts consuming more calories than she needs, her body gets the signal that there are ample resources to have more babies, and mom starts ovulating (and menstruating) again. 

The average duration of lactational amenorrhea in exclusively breastfeeding (no formula, foods, or anything else) mothers in the US is about 6 months.4  This coincides fairly well with the start of the introduction of solid foods, which may begin to reduce nursing intensity.  Before then, the lactational amenorrhea method can even be used as a form of birth control, believed to be about 98% effective provided you follow these rules:5-6

Lactational Amenorrhea Method

  1. Baby must be less than 6 months old.
  2. Mom must not have had a return of menses (defined as 2 contiguous days of bleeding, 2 contiguous days of spotting and 1 day of bleeding, or 3 contiguous days of spotting)
  3.  Mom is exclusively breastfeeding her baby with no more than 4 hours between daytime feeds and no more than 6 hours between night time feeds and no more than 10% of calories coming from supplementation with infant formula or complementary food5-6

As for me, I’m glad there’s data to explain my experience!

When did you get your period back while breastfeeding? Did it differ between children?




1.            C.C.K Tay AG, A. McNeilly. Twenty-four hour patterns of prolactin secretion during lactation and the relationship to suckling and the resumption of fertility in breast-feeding women. Human Reproduction 1996;11(5):950-955.

2.            McNeilly AS, Tay CCK, Glasier A. Physiological Mechanisms Underlying Lactational Amenorrhea. Annals of the New York Academy of Sciences 1994;709(1):145-155.

3.            Valeggia C, Ellison PT. Interactions between metabolic and reproductive functions in the resumption of postpartum fecundity. Am J Hum Biol 2009;21(4):559-66.

4.            Heinig MJ N-RL, Peerson JM, Dewey KG. Factors related to duration of postpartum amenorrhoea among USA women with prolonged lactation. J Biosoc Sci. 1994;26(4):517-27.

5.            Hight-Laukaran V, Labbok MH, Peterson AE, Fletcher V, von Hertzen H, Van Look PFA. Multicenter study of the Lactational Amenorrhea Method (LAM): II. Acceptability, utility, and policy implications. Contraception 1997;55(6):337-346.

6.            Peterson AE, Peŕez-Escamilla R, Labboka MH, Hight V, von Hertzen H, Van Look P. Multicenter study of the lactational amenorrhea method (LAM) III: effectiveness, duration, and satisfaction with reduced client–provider contact. Contraception 2000;62(5):221-230.


Outrage sparks Twitter battle between UN health watchdogs WHO, PAHO

News Release November 16, 2012

 Outrage sparks Twitter battle between UN health watchdogs WHO, PAHO

Moms, front line breastfeeding workers furious with Pan American Health Organization for accepting $150,000 from Nestlé

Two global public health titans are duking it out on Twitter over the ethics of accepting money from food industry giants to fight non-communicable disease.

This comes after moms and front line health care workers vented their fury at the Pan American Health Office – the regional representative in the Americas for the World Health Organization – over $150,000 received from Nestlé.

After fighting industry for years to uphold an international code to protect moms and babies from predatory marketing, there was outrage when it was learned PAHO accepted $150,000 from Nestlé. This is a direct violation of what is known as the WHO Code and moms and breastfeeding support workers are furious.


“No matter how PAHO-WHO spins it, accepting cash handouts from Nestle is an endorsement of their products, and a green light to Nestle to continue to harm the health of children by violating the WHO Code,” says Jennie Bever, a breastfeeding researcher and mom of two who wrote a blog post triggering the outcry on social media. “We’re fighting this battle while nursing our babies, picking up our kids from school and doing our jobs. It is our health and the health of our children the world over that PAHOWHO is selling to the highest bidder.”


While the health protection titans hash it out with careful language, moms and the lactation consultants who help them say it’s simple. PAHO must give the money back.


Marsha Walker, executive director of the US-based National Alliance for Breastfeeding Advocacy, said in an article on the issue: “The wolf in sheep’s clothing comes bearing money and is rewarded for its poor corporate behavior by aligning itself with the good name of respected health agencies.”


Our newly-formed group, Friends of the WHO Code is asking other organizations to join our effort and pressure the WHO and PAHO-WHO to reexamine this and other relationships and how they impact global public health. We can be reached at


– 30 –


Contact:  Dr. Jennie Bever Babendure




Link to Jennie Bever’s blog post:

Link to Marsha Walker’s article:



Media are invited to contact Amber Rhoton McCann, IBCLC, for more details on the social media response to this issue, and Marsha Walker, RN, IBCLC, Executive Director, National Alliance for Breastfeeding Advocacy (NABA), for more information about the WHO Code. Background on issue is attached.



On October 19, 2012 Reuters broke the story that the Pan American Health Office (PAHO-WHO) of the World Health Organization (WHO) had accepted $150,000 from Nestle. In addition to what most know as a chocolate company, Nestle is a multibillion dollar corporation in direct conflict with the WHO International Code of Marketing Breastmilk Substitutes (the WHO Code). Due to the aggressive marketing of their infant feeding products in the 3rd world, Nestle has been the subject of an international boycott for the past 35 years.


Based on the aggressive and predatory tactics of companies such as Nestlé, in 1981 the World Health Organization and UNICEF, supported by 118 countries[1], brought in the WHO Code to protect vulnerable children who may suffer poor health and even death due to lack of breastfeeding, especially in places without access to clean water and proper sanitation. This public endorsement of the importance of breastfeeding was a critical step for public health worldwide, and has since guided legislation in 103 of countries to enforce all or part of the WHO Code. Over 20 other countries adopted the code on a voluntary basis[2].


Unfortunately in the US and many other countries, a lack of legislative enforcement of the WHO Code has resulted in over 30 years of rampant violations. From the “gift” bag at the hospital to delivery of formula samples on mothers’ doorsteps, infant formula manufacturers have continued to violate the WHO Code, and negatively impact breastfeeding. These violations have intensified in recent years as corporations have begun to infiltrate social media to market their products directly to new mothers. In the fight against these aggressive tactics, the support of the WHO through the WHO Code has been the main source of strength for advocates worldwide. By partnering with Nestlé, PAHO-WHO has endorsed one of the worst violators it initially set out to regulate. This relationship serves as a symbol to other organizations that the WHO Code has no meaning, sending a message to other companies that such marketing tactics will be overlooked.


The gravity of this action has sparked worldwide outrage and demand for the WHO to reexamine their relationship with Nestle and return the $150,000. This action is such a breach of trust between the WHO and the people it protects that it has united a global front of breastfeeding advocates, public health professionals, mothers and fathers to stand up to organizations that violate the WHO Code, including PAHO-WHO itself. In order for the WHO Code to maintain its integrity, PAHO-WHO must return the funds, as a monetary relationship with Nestlé symbolizes a nail in the coffin of the cause and gives a green light to code violators that the WHO Code has no meaning.




[1] WHO, International Code of Marketing of Breast-milk Substitutes, (Introduction, p. 5)


[2] UNICEF, National Implementation of the International Code of Marketing of Breastmilk Substitutes (April 2011)

WHO Sells out to Nestle

Recently, I blogged for the International Lactation Consultant Association about the decision by the World Health Organization (WHO) to accept corporate funding from food giant, formula manufacturer and WHO Code Violator Nestle.  This action has led to outrage from mothers, fathers, lactation professionals and public health advocates who are banding together to be a unified voice for change.  In this guest post, longtime WHO Code advocate and Executive Director of the National Alliance for Breastfeeding Advocacy (NABA), Marsha Walker, discusses the ramifications of this enormous error in judgement and what you can do to help us influence WHO to rescind their agreement with Nestle.

This post also appears at Human Milk News and will appear in the NABA website and in the United States Lactation Consultant Association (USLCA) Monthly Newsletter.

World Health Organization Sells Out to Nestle

by Marsha Walker RN, IBCLC

Nestle has bought a seat at the policy-making table of the World Health Organization. WHO has accepted funding from Nestle for  WHO’s obesity reduction initiative. A Reuters news article reported that the Pan American Health Organization (PAHO), WHO’s regional office for the Americas, accepted $150,000 from Nestle to help reduce the very problem to which Nestle products contribute. Cash-strapped WHO has started to rely on corporate offenders such as Nestle and Coca-Cola to fund its health initiatives, placing itself in a massive conflict of interest, as policy is shaped by companies who stand to gain the most from the ill health their products promote. Disease promoting corporations have found that it much more profitable to invest in a seat at the policy-making table to avoid sanctions, monitoring, and regulation than it is to cease producing the products that contribute to chronic diseases and conditions such as obesity.

The wolf in sheep’s clothing comes bearing money and is rewarded for its poor corporate behavior by aligning itself with the good name of respected health agencies.

Breastfeeding advocates who are staunch supporters of the International Code of Marketing of Breastmilk Substitutes (the Code) are aghast that WHO is violating its own Code. By abdicating its responsibility to infants and mothers, WHO is modeling the very behavior the Code was created to prevent. This blow to the Code may seem overwhelming to those who work so hard to support breastfeeding mothers. Even though we do not have the unlimited funding of large corporations we have our voices that can be raised together so that WHO might hear us. Consider joining the Friends of the WHO Code Facebook group. We can harness social media to let WHO know how we feel. Post to WHO’s Facebook page, tweet @WHO to let WHO know how damaging this conflict of interest is to the Code. Of course, be ready for Nestle’s response. Nestle has what they call their Digital Acceleration Team that monitors hot spots in the social media and jumps in quickly to apply damage control when Nestle or its products are unfavorably mentioned.

Let’s use what we have at our fingertips to right an egregious wrong.

Marsha Walker, RN, IBCLC
Executive Director, National Alliance for Breastfeeding Advocacy


Is it time breastfeeding supporters began to think like formula companies?

copyright Kristen Self photography 2011

Before my second son was born, I had big plans for my maternity leave.  I was going to reorganize all the closets, get the garage in order, make scrapbooks for both children, and finish a quilt for my older son’s bed, all while taking care of my beautiful new baby.  It was my second time around, I told myself, piece of cake!

Those of you who are smiling know what I did on my maternity leave—nurse the baby, rock the baby, change the baby, play with the baby, watch the baby’s eyelashes uncurl while he was sleeping, and try my best to remember to eat and sleep in short snatches day or night between doing all that.  That was pretty much all I could handle.  I would have laughed at my former self then if I had the time, but between that, mastitis, and falling down the stairs at 3 weeks (likely due to sleep deprivation), I feel like we made it out of the first month by the skin of our teeth.

So when writing a post for Lactation Matters I read this conclusion about the impact of breastfeeding support on breastfeeding duration and exclusivity in a recent Cochrane review of breastfeeding support interventions:

“Support that is only offered when women seek help is unlikely to be effective”

I almost laughed out loud…

As a private practice lactation consultant, I am definitely not belittling my contributions to help moms and babies breastfeed when they seek help.  I certainly do help moms and babies breastfeed longer and more exclusively, and so do countless other lactation professionals.  Some women even send me pictures of their beautiful breastfed babies at 6 and 12 months to prove it!

What struck me about this conclusion (and the reason I laughed) was that it was so obvious and so true.  We don’t expect moms with new babies to be able to do their laundry, clean their houses or even prepare their own meals.  We show up at their doors with casseroles and crockery and grocery bags full of goodies.  We offer to hold the baby so they can do such basic things as take a shower, take a nap, or eat.  Yet when breastfeeding isn’t going right for them, we expect them to ask for help.

New mommies are sleep deprived, hurting in places they don’t want to talk about, crying at the drop of a hat and spending every waking and sleeping moment overwhelmed by caring for a helpless human being.  Even if they know they need help, only a few will have the knowledge, motivation, and energy to seek it out.  It is those few (and those with knowledgeable and motivated husbands, friends or family) that I have the pleasure of working with.  Countless others don’t know where to find help, can’t afford it, or are convinced by family, friends or society that their obstacles are insurmountable and that they can’t or shouldn’t continue breastfeeding.   

As much as we think formula companies don’t get it, they’ve done a thorough job of understanding mothers.  They figured out long ago that the best way to sell their product was to think about the needs of their target consumers. So they strive to make formula as available as possible to a sleep deprived, overwhelmed and vulnerable new mother.  Everywhere you look, formula is there: in the gift bag from the first OB visit, on the pages of the parenting magazines, on the shelves of the drugstore, the grocery store, the discount store, in the discharge bag from the hospital, in the pediatric office, and lately, even delivered to your doorstep at 36 weeks, 1 month, 2 months and 3 months.  Moms don’t need to call anyone, drive anywhere, or ask for help.  The formula is ready and waiting.  Its sheer availability is a message in itself:  We’re here if you need us, any time of the day or night, just in case.

Compare that to the current system of lactation support in the US.  Most mothers give birth in hospitals with maternity care practices that do not support their efforts to breastfeed, and 25% of their babies are given formula before they are even 2 days old.  Most mothers will receive conflicting and inadequate advice on how to breastfeed, and will leave the hospital with the confusing message of “you should definitely breastfeed, and here’s a pretty diaper bag full of formula.”  Once home, mothers are expected to figure out breastfeeding on their own, seek out support from a lactation professional at their own expense, or try to find, join and get support from a support group run by volunteers, often while being encouraged to quit by their friends and family, even their physicians.

Imagine if formula companies made their products so difficult to access.  They’d have a hard time maintaining a business, much less turning a profit.  Yet this is the status of breastfeeding support in the United States.  We have a superb product, it’s better than anything else on the market will ever be, so good our competitors spend millions of dollars trying to copy it.   Yet they are winning–in large part because they have a better marketing strategy.

To compete we have to make a systematic change.  If the United States is to see a real increase in breastfeeding duration and exclusivity, we have to start thinking like the formula companies. They don’t wait for moms to ask for their products, they deliver them to their hospitals, to their doctor’s offices, to their doorsteps.    The article concludes that “women should be offered ongoing visits on a scheduled basis so they can predict that support will be available.”  What if breastfeeding help was integrated into our healthcare system, making it part of every visit you made to the obstetrician or midwife’s office and continued at every pediatric office visit after the baby was born?  What if a nurse, a lactation consultant, a peer counselor or a friend came to your house on a scheduled basis to help with breastfeeding and everything else?  What if this type of proactive breastfeeding help was covered by insurance as part of your maternity care?  What if you could expect to have breastfeeding support delivered to your home, just like a can of formula?  Imagine the impact!

How can we make this happen?  We need to start to expect something better.  We need to start realizing that we are consumers of the type of care we are being given, and consumers drive the market.  Tell your insurance company that they should cover lactation consultant services, and applaud them when they do.  Tell your hospital that you expect them to provide skilled lactation services to everyone, and write to complain if they don’t, or better yet, make a point to deliver at a Baby Friendly hospital.  Choose an OB or midwife who supports breastfeeding, and question them if they seem ambivalent or hand out formula or coupons.  Choose a pediatric office that has a lactation consultant on staff, and let them know you want to see her at your scheduled visits until you are breastfeeding well.

The article concluded that breastfeeding support DOES make a difference, in fact the article is chock full of strategies that work.  All of them are PROACTIVE.  None of them expect mothers to be able to ask for help. They all say:  We’re here if you need us, any time of the day or night, just in case.

My comments on the rest of the excellent review and meta-analysis described above (including all the major findings), are available at ILCA’s Lactation Matters blog.



Can Music Change Your Milk?

photo copyright Kristen Self Photography 2011

With more and more moms using breast pumps to express milk for their babies, the question on many of their minds is “How can I express more milk?”  In addition to Jane Morton’s work with “hands-on pumping,” a recent pilot study from Advances in Neonatal Care may begin to give us some clues.  When Douglas Keith and his colleagues randomized 162 mothers of critically ill infants to 1 of 3 different listening interventions or normal care while pumping breastmilk, they made an interesting discovery: all mothers who listened to audio content meant to induce relaxation produced more milk.  The interventions consisted of 1) a guided imagery protocol for breastfeeding alone, 2) a guided imagery protocol accompanied by guitar lullabies, or 3) a guided imagery protocol accompanied both by guitar lullabies and a series of images of the mother’s infant on a hands-free stand. All interventions resulted in significantly increased milk quantity compared to normal care.  Mothers who listened to the study’s guided imagery protocol accompanied by both guitar lullabies and images of their infants produced the greatest quantity of milk, and their milk had significantly higher fat content.  Interestingly, the caloric content of the milk was the same for all groups.

For me, the most important finding of this study was that changing the maternal environment through auditory and visual stimuli could dramatically change both milk quantity and composition.  The relaxation and soothing feelings elicited by holding, touching and breastfeeding a newborn may be harder to come by for mothers of babies in the Neonatal Intensive Care Unit (NICU).  Changing their auditory and visual environment may help them block out distraction and cultivate a state of relaxation resulting in greater milk production.  Although the authors hypothesize that the increases in milk quantity could be due to oxytocin, this study did not investigate the cause of the observed changes.

I used to find that I expressed more milk when I pumped with friends.   Did you notice any difference in the quantity or fat content of your milk when pumping in different situations?

Happy Birthday Breastfeeding Science!

I’m sure I’m not the first person to compare the conception of an idea, its incubation, development and eventual presentation to the world to conception, pregnancy and birth.  Maybe you’ll give me a bit of leeway as my little guy is still small enough to softly snore as he snuggles skin to skin on my chest, and the waiting, work, emotion, and joy of his birth are still fresh in my mind.

Just as I have hopes and dreams that my sons will grow to be happy well-adjusted boys and men, I have hopes that this blog, breastfeeding science, will grow to become a happy well-adjusted place to find useful evidence-based information from the scores of research articles that I have found relevant to my journey as a mother, International Board Certified Lactation Consultant and breastfeeding researcher.

So in the exhuberant afterglow of birth and the dreams I have for a brilliant future,  Happy Birthday to our newest addition: