Members of the medical community have good reason to be very skeptical of studies with this kind of design. Here's why: It is extremely difficult to exclude the possibility that mothers who breastfeed differ from mothers who don't in very important ways and the boost in IQ is a result of those differences.

Ms. Bazelon states: "Caspi and Moffitt, however, controlled for the confounding factors of social class and maternal IQ", as if that settles the issue.

Firstly, "controlling" for these factors involves some statistical techniques which are of doubtful validity. For example, the most common way to control for unbalanced factors in two groups is to use a multivariate linear regression to tease out the effect of individual factors, which assumes that all the factors (maternal IQ, socioeconomic status) impact on the final outcome (in this case IQ) linearly. If the factor in question does not impact on IQ linearly, then using this technique to "control" for that factor is hogwash. It's done all the time and it's well-accepted scientifically, but it's on much shakier theoretical ground than even most scientists realize.

Secondly, there is always the possibility (in my opinion, a very strong possibility) that mothers who breastfeed differ from mothers who don't in very substantial ways that no attempt has been made to control for. Maybe mothers who breastfeed spend more time with their babies in general, talk to them more, smoke less, adhere to their doctor's advice more - the list of possibilities is endless.

If the above doesn't convince you, consider this. It was precisely studies of this kind that purported to show that hormone replacement therapy for post-menopausal women saved lives. Doctors were reassured that every conceivable confounding factor had been taken into account and "controlled for", with the final result being that hormone replacement was a great thing. Women who got hormone replacement in these studies DID live longer and get fewer diseases.

But when more rigorous studies were done, it turned out to be completely wrong. Hormone replacement therapy didn't save lives - it killed! The reason women who took it lived longer in those earlier studies was because they were DIFFERENT than the women who didn't in many other ways that had nothing to do with hormone replacement therapy, despite all the researchers' assurances that everything had been "controlled for".

As a result, a generation of women was exposed to needless risk based on faulty science, and thousands probably died. In my opinion, it is one of the great shames of modern medicine. It was exactly the same kind of study design that led to that tragic result, so think twice before believing stuff like this.

It seems to me that you wasted an awfully massive amount of time and energy on something admittedly non-sensical.

As a mother who was not, for very valid medical reasons and despite much heartbreaking effort, able to breastfeed, I resent the ongoing and accepted implication that either this situation is unusual or that it implies something about me as a mother. These implications range from factors one cannot change, such as having a low income, to being poorly educated, to smoking in front of my child and virtually ignoring her.

I am a highly educated women in my 30s. I don't smoke, put my baby at risk, etc. I'm currently staying at home with my daughter, talking to her, playing with her, reading to her, and helping her learn and grow. But, so the popular wisdom goes, this is not enough--she needed to be breastfed.

I am raising a healthy, happy, and incredibly bright little girl. And despite criticism from friends and complete strangers that she was bottle-fed, she's doing remarkably well. Go figure!

So where were you when the so-called "conclusions" that were leapt to by this badly designed study of post-menopausal horomones were proved to be completely erroneous? Where were you when the designers of said study were forced to admit in public that giving massive doses of horomone to women who were up to 30 years post-menopause was not the brightest thing to do?

I suspect that you are completely clueless about anything related to menopause, and I know that you are too willing to dismiss 60 years of history regarding the use of horomone replacement drugs.

Next time, pick an example that you can actually back up.

I agree, mnemon -

I wasn't breastfed...

Mom plopped me in front of the TV while she was cleaning house...

Dad thought kindergarten was a waste of time...

There were few books in the house...But we did have the NY Daily News.

When I began first grade, I was considerably ahead of the class in both reading and math. I was considered "gifted" at the time. How?

'Splain that one in the studies!

This study did not say that if you werent breastfed, you are going to be stupid. It says that studies happen to notice that children who were breastfed, tend to have higher IQ's. I was not breastfed, although for some reason my mother breastfed both my older brother & sister. That is why this article made sense to me. Both my brother & sister scored above genious (did i spell that right?) level on there IQ tests. I on the other hand did not do so well, although i scored higher than average. Not to say that im not smart, I have a degree, I have a kick ass job, and personally i think i have way more common sense that my oh so smart brother & sister. If you did not breastfeed, don't let this article make you feel at all guilty. It seems to me that just because some studies have been made that promote breastfeeding, alot of women become defensive who did not breastfeed. C'mon we all know that formula will never perfectly mimic nature's milk, but we all make desicions to best fit our lifestyle. to breastfeed or not is a personal decision, don't let some article get you all devensive because you chose not to. if you do/did breastfeed great! more power to you! if not who cares! you still have a child, and probly an extremely smart healthy one.

also, i think comparing this article to the hormone replacement therepy thing is absolutley ridiculouse. that is just sooo over dramatic. get over your guilt for not breastfeeding. it's really ok! is your child happy? that is all that matters.

i suck at spelling...sorry. if only my mother breastfed me.....naw just kidding!

I agree that studies like this are useless and that they "controlled for everything" whatever!!! Did they monitor how many and which type of prenatal vitamin the mother did or did not take--amount of morning sickness (vomiting out the vitamin)---amount of orange juice consumed--amount and type of veggies and fruits--any fish/meat/protein/diary products eaten and which kinds while pregnant--how many times did the child eat--what did the mother eat before feeding the child--how many times per day was child kissed/hugged/bathed/rocked---­was there an animal in the house while mom was pregnant---was animal there after child arrived--how dusty was the home--did mom go outside much while pregnant--does the mother have any allergies--did she develop any while pregnant---what about dad: what did he eat/drink before creating the child---what type of water does the family drink/make the formula with--was this a planned or surprise child---what if any types of birth control had been used before getting pregnant--

The list of things to control for--to make sure that ONLY thing that is being tested is breast-milk vs. a specific brand/type of formula--that list con go on forever--these are things that I just thought of in 2 minutes! How many other factors..both environmental and genetic.... are variable?! Tons!

Just shut up and feed your kid! I don't see people yelling at others about eat McDonalds vs Burger King or anything else once the kid is old enough to stop breastfeeding, Why do both sides get so worked up about it and have to fight and try to "win".

Feed junior, hug him, kiss him, love, him and raise him to not be a brat!

Last time I checked, there wasn't a spot on the college application/job application that asked whether you were or weren't breastfed! Who cares?! Just feed them and raise, and love them!

Honestly, its just not that important! I successfully breastfed all three of my daughters for 6 months, 14 months, and the last for 3 years. I celebrated the closeness and cuddling that only I could cherish, yes, even at the wee hours of the morning during those every 2-hour feedings. My daughters are grown now and I can honestly say that I doubt that it made much (if any) difference in their development....its all in the upbringing and nurturing really, but for me it was special.....something I could do for them that no one else could. I know moms who breasfed their kids and then turned out to be terrible mothers! Its not the breasfeeding, its the nurturing and loving that grows the child. I think society makes too big a deal of the whole issue....I had people stare while I breastfed my children in public (I was totally covered by the way) like we were from outer space, and even some asked me why I STILL nursed after one year. NO ONES business. If a mom chooses to bottle feed, she is no less a mom, its NO ONES business.....shouldnt we focus on the time we spend with our children, how we show them we love them, NOT what type of milk we serve them?