Oftentimes you’ll hear people citing scientific articles to back up a parenting decision – and this falls on both sides of almost any parenting practice.  Depending on how the data is presented and interpreted, you can generally find scientific articles out there to support your point of view.  It’s why a critical reading of the literature (and any given study) is so very important, along with understanding the implications while bearing other research in mind.  But despite all the articles and points of view, there are some things we just simply don’t know.  Things that may be near and dear to people’s hearts, but that we just simply don’t have the information to make educated conclusions about.  Here I’d like to discuss some of these things and some of the related research we do know which might explain why so many people believe we know more than we do.

1.  The long-term neurological effects of crying-it-out

Source: Unknown

Source: Unknown

I know, I know – most people reading this hate any form of crying-it-out and will want to talk about all those studies showing damaging effects to the brain with respect to prolonged stress responses, and you’re right to.  Given what we do know, it’s the best place to take our cues.  As I talked about in the piece on crying-it-out, there is evidence that prolonged stress and separation is damaging to infants’ stress responses and long-term neurological development.  However, as I also mentioned, none of these studies looked at crying-it-out specifically.  In fact, only one study has specifically looked at stress responses with respect to crying-it-out[1] and while the early evidence does suggest that the experience of crying-it-out is highly stressful to infants in the moment (despite not showing behavioural distress markers like crying), the long-term effects remain unknown.

This lack of knowledge means that people are extrapolating from other evidence to suggest what might happen long-term.  While some of us will believe that it’s logical to extrapolate data from other instances of parent-child separation to crying-it-out or work showing long-term neurological effects of crying and heightened stress, the fact is that these studies don’t clearly combine all the elements that are at play in crying-it-out.  For example, is there a distinction between crying-it-out and “controlled crying” where parents check on their child and offer some form of comfort or responsiveness?  Does temperament play a role?  After all, we know that highly fearful and “difficult” children respond very differently to many parental acts, with important and long-term consequences.  Luckily for us, Dr. Middlemiss, the lead researcher of the one study that has looked at stress responses, is looking at this issue, starting with three months post-training.  So, for this question at least, it seems it should be just a matter of time before we know the answers, or at least begin to know the answers!

2.  The long-term effects of the current dose of aluminum adjuvants in vaccines

Source: Unknown

Source: Unknown

I’ve said it elsewhere and I’ll say it again here – I believe vaccination to be a topic in which parents need to educate themselves and make a decision they are comfortable with for their child and their society.  But as many people have realized, we as parents (and doctors and other researchers) are lacking some of the information that would make things much easier for us in accepting vaccination.  One of the biggest concerns are to do with the adjuvants used to make the vaccine effective (though this is not the case for live viruses like the MMR vaccine).  In short, vaccines on their own are not strong enough to elicit an immune response in individuals and thus something needs to be added to force our immune system to respond when a live virus isn’t used.  In the case of vaccines, currently that adjuvant is aluminum (in fact, in the USA it’s the only adjuvant licensed for use) in the form of aluminum salt or gel.  Aluminum is a toxin to humans even though we are exposed to quite a bit on a daily basis.  As with most things, dose is key – small doses of aluminum will not hurt us, but larger doses can.  This is why most countries have advisory panels to determine if the doses we’re exposed to on a regular basis are posing health problems to the population at large[2][3].  But as rightly pointed out by many, aluminum has been used in vaccines for nearly 80 years.  So what’s the problem?

What is often overlooked (in my opinion) is that aluminum was only used in small amounts with the diphtheria and tetanus vaccines meaning the exposure for individuals was quite low.  In fact, until the mid-80s, only the DTP vaccine included aluminum as children weren’t vaccinated nearly as much as they are today[4].  In fact, in the 1950s children received a total of 5 shots by their 2nd birthday while today’s children will receive 24[4].  It is precisely this increase that has led people to be concerned about what exactly is going into these vaccines and why so many more are needed given that rates of these communicable diseases dropped dramatically at the introduction of vaccines 50 years ago.  Add to this that the use of vaccine blends (e.g., DTaP-Hib) in which the amount of aluminum often exceeds the sum of the amounts in the individual component vaccines (though it must be stated that blends are often far more effective than the individual components).  Finally, that there have actually been no studies comparing long-term outcomes of aluminum exposure in vaccinated and non-vaccinated children, despite knowledge that aluminum toxicity is a possibility (see [5] for a review) and some research that suggests aluminum (even if the form of an adjuvant in vaccines) may induce immunoexcitotoxicity which can lead to neurodevelopmental disorders[6].  While these research is equivocal and controversial, parents will not feel comfortable with people just saying “Don’t worry about it”, especially when it’s clear that our current vaccination schedule is far more intensive and different than in previous eras.

In many cases, people will feel that the risks of aluminum are far less than the risks of not vaccinating.  And others will feel differently.  Personally, I just think it’s an avenue that needs exploring and given the preponderance of non-vaccinated children these days, it’s a research question that is doable.  And then hopefully, parents can be given full information on what it is that it is being used in the vaccines they are asked to administer to their children so they can make real, educated decisions.

3.  The health benefits of normal/long/full-term breastfeeding

Source: Unknown

Source: Unknown

Agree with me – this sounds weird, right?  Especially as I’ve written pieces on the topic.   But as I’ve said in what I’ve written, I’m going on what we do know combined with common sense.  Personally I don’t think it’s an avenue that’s going to lead me astray, but if I have to be 100% clear here – science hasn’t bothered to research the health effects of breastfeeding beyond a year.  I would like to say it’s because they realize there are positive effects and so why bother, but we all know that’s not the case.  I imagine part of the reason is that very few people do breastfeed beyond a year in America, which is where the preponderance of research comes from, but also because our culture isn’t set up to support breastfeeding, especially breastfeeding beyond America’s norms, and so why even look for benefits to something that would be difficult for most parents to achieve?  Best to ignore to question altogether.

Except… that whole common sense thing.  As I stated here, there is some health evidence of the benefits to mom with respect to cancer rates – namely that not breastfeeding beyond a year or two years has a pretty crappy rate of return in that you increase your chances of getting breast cancer[7][8].  But when we look at kids, there’s virtually nothing.  Yes, many childhood cancer rates are much lower in children who breastfeed longer[9][10][11], but most of these examinations look only at greater than six months, while some only look at ever breastfed versus not at all.  There is also ample evidence regarding the benefits of breastfeeding to a plethora of other diseases and health factors (e.g., obesity)[12].  While these are important questions, it does not provide much evidence that specifically looks at older children.  Of course, as I’ve argued before (and has been argued as well by other researchers, see [13]), the idea that somehow at a year the benefits stop seems rather asinine.  We know the composition of breastmilk changes, but not too dramatically relative to its health value, so why would it suddenly not be of any benefit?  No one is saying the benefits are as great as they are in infancy, but that also doesn’t mean that there are no benefits.

However, the fact that people continue to presume there is “no point” to breastfeeding past a year, or six months, or three months, or at all, suggests that research into actually showing the health benefits of breastfeeding are much needed.  It is one area of research that I believe is sorely lacking.  And if it does work out as many of us believe, it would be one more reason for society to adopt views and policies that reflect the ongoing benefits of breastfeeding between a mother and child.


The point of this post is really to advocate for more research where it’s needed, but to be honest, it’s also to humble us.  Personally, I know I believe what I believe with respect to the parenting literature, and I know that I honestly believe I am always doing best for my child, but when I try to discuss or debate with others, I sometimes feel like I’m in the twilight zone because they are simply coming from a totally different perspective using the same literature.  And that is too weird.  Yet inevitable when science doesn’t actually answer the questions we need to be able to both make educated decisions and have intelligent, educated discussions.  I once gave a more-than-usual thorough explanation of why I felt as I did about a certain topic (i.e., CIO), but even that was in response to someone who very clearly felt differently and while appreciative of the in-depth response I provided, seemed to take none of it to heart when making her own post on the topic.  This type of thing comes up with the most controversial of parenting topics which is why you see three of them here – breastfeeding, crying-it-out, and vaccination (I leave circumcision out because I’ve done a full summary here and feel the evidence is pretty conclusive despite the AAP and others disagreeing).  I believe the reason these topics remain controversial is because the in our science-loving world, people will not accept anything that goes against what they’ve done or want to do unless there is hard evidence against it.  However, I think in some cases common sense prevails (e.g., how can we believe that leaving your child to scream is “helping”?) but I realize common sense isn’t something that we all agree on or listen to – it’s why science has come along.  So we need science to provide that evidence.  And here’s hoping science is listening and taking notes.

Recommended Reading After the References

[1] Middlemiss W, Granger DA, Goldberg WA, Nathans L.  Asynchrony of mother-infant hypothalamic-pituitary-adrenal axis activity following extinction of infant crying responses induced during the transition to sleep.  Early Human Development 2012; 88: 227-32.

[3] Scientific Opinion of the Panel on Food Additives, Flavourings, Processing Aids and Food Contact Materials on a request from European Commission on Safety of aluminium from dietary intake. The EFSA Journal 2008; 754: 1-34

[5] Tomljenovic L, Shaw CA.  Mechanisms of aluminum adjuvant toxicity and autoimmunity in pediatric populations.  Lupus 2012; 21: 223-30.

[6] Blaylock RL.  Aluminum induced immunoexcitotoxicity in neurodevelopmental and neurodegenerative disorders.  Current Inorganic Chemistry 2012; 2: 1-8.

[7] Collaborative Group on Hormonal Factors in Breast Cancer.  Breast cancer and breastfeeding: collaborative reanalysis of individual data from 47 epidemiological studies in 30 countries, including 50 302 women with breast cancer and 96 973 women without the disease.  The Lancet 2002; 360: 187-95.

[8] The Cancer and Steroid Hormone Study Group.  The independent associations of parity, age at first full term pregnancy, and duration of breastfeeding with the risk of breast cancer.  Journal of Clinical Epidemiology 1989; 42: 963-73.

[9] Golding J, Paterson M, & Kinlen J.  Factors associated with childhood cancer in a national cohort study.  British Journal of Cancer (1990); 62: 304-308.

[10] Martin RM, Gunnell D, Owen CG, & Smith GD.  Breast-feeding and childhood cancer: a systematic review with metaanalysis.  International Journal of Cancer (2005); 117: 1020-1031.

[11] Davis MK, Savitz DA, & Graubard AI.  Infant feeding and childhood cancer.  The Lancet (1988); 332: 365-368.

[12] Bartick, Melissa, and Arnold Reinhold. The Burden of Suboptimal Breastfeeding in the United States: A Pediatric Cost Analysis. Pediatrics  2010; 125: 1048-56.

[13] Piovanetti Y.  Breastfeeding beyond 12 months: an historical perspective.  Pediatric Clinics of North America 2001; 48: 199-206.