Bigger Babies Are Brainier at Birth, Scientists Say

By Mike Collett-White

LONDON (Reuters) - The bigger you are at birth the brainier you tend to be in childhood, scientists said on Friday.

While it has been established already that IQ at school is linked to birth weight among light babies, new research shows there is a correlation between intelligence and size among children of normal birth weight.

``The focus has tended to be on lightweight babies,'' said Thomas Matte, senior epidemiologist at the New York Academy of Medicine and co-author of the study published in the British Medical Journal.

``This research suggests the need to look at birth weight across the whole range of babies,'' he told Reuters.

Researchers at the Academy and at Columbia University examined the relation between birth weight and measured intelligence at age seven years in nearly 3,500 children.

Most fell within the normal weight range, defined as exceeding 2,500 grams.

They found that there was a direct correlation between weight at birth and Intelligence Quotient (IQ) at age seven, even after factors such as mother's age, race, education and socio-economic status were taken into account.

The association was stronger in boys than in girls. The scientists found that a 1,000-gramme increase in birth weight related to a 4.6-point increase in IQ among boys but only 2.8-point increase among girls.

Matte said that he was puzzled by the difference between the sexes. When siblings were compared, removing factors which could affect IQ such as education and social environment, the link between weight and intelligence in girls was weak.

``In girl siblings the relationship is not statistically significant,'' he said. ``There is a difference in the brain development of boys and girls, and so boys may be more sensitive to factors restricting fetal growth.''

``Boys are also larger at birth and grow more rapidly, so if something is restraining fetal growth this may also make them more sensitive.''

Matte said research into the link between birth weight and intelligence was too sketchy to be useful for any practical or clinical application, but with time may prove valuable.

``There are programs aimed at reducing the risk of low birth weight now and these need to continue,'' he said.

Women who smoked during pregnancy, for example, tended to have lightweight babies because they were born early.

-- (cin@cin.cin), August 10, 2001

Answers

At birth, my hat size was 8.

-- (nemesis@awol.com), August 10, 2001.

Yes son, you are why I never had more children.

-- (nemesis' mom@awol.com), August 10, 2001.

LOL nemesis you goofball =)

-- (cin@cin.cin), August 10, 2001.

Women who smoked during pregnancy, for example, tended to have lightweight babies because they were born early.

I don't believe this study, Cin, and babies born to smokers are NOT born earlier. My firstborn was 5 13. The secondborn was 6 13. The third was 7 11. The more you have, it seems the bigger they get. I smoked during all three pregnancies and all three scored around the 145-150 range on IQ tests.

-- Anita (Anita_S3@hotmail.com), August 10, 2001.

Anita, ever hear of a bell curve? Do you know what statistical significance means? Have you ever seen an X-Y plot of data?

-- Duh (slap@my.forehead), August 10, 2001.

Anita, I don't necessarily believe it either, but was just throwing it out there for discussion. Though I DO believe smoking contributes to smaller birthweight, and is generally harmful to the fetus.

-- (cin@cin.cin), August 10, 2001.

Cin: Yes...smoking DOES contribute to a lower birth weight, but NOT because they come out earlier. Actually, I had good reason to try and keep the birth weight low. My pediatrician had told me that my cervical bone structure was VERY close together [in other words, VERY slim hips], and that if I had a baby larger than 6 lbs. it would break my cervical bones on delivery. Little did she know [nor could it be anticipated] that my cervical bones would unhinge [much like a snake's jaw] at the appropriate time. THAT was pretty cool. I even purchased a straight skirt because *I* had hips. Okay...the whole deal went back together in a week or two, but it was fun for a short time.

Duh: I didn't study mathematics for 16 years to NOT be familiar with statistics, bell curves, or X-Y plots. I just don't hold any credence in some of these studies. What good is a study if you and everyone you know is an exception?

-- Anita (Anita_S3@hotmail.com), August 10, 2001.

Lower birth weight among babies born to mothers who smoke has been attributed to carbon monoxide, I think.

-- helen (just@say.snow), August 10, 2001.

"if I had a baby larger than 6 lbs. it would break my cervical bones on delivery"

Why would your pediatrician give you this advice? LOL

Of course the woman's hips loosen up before and during delivery. And, the baby's head isn't 'solid' but moves in plates. Ever wonder 'bout that? Nature finds a way. You have a stupid pediatrician.

"everyone you know is an exception" And of course YOU know everyone! LOL

-- Duh (slap@my.forehead), August 10, 2001.

Duh: Did you ever study LOGIC? That was a HUGE leap from "everyone I know" to "I know everyone."

My point IS [and always WAS] that if a study demonstrates a particular section of society to be outside the range of its statistics, then that section of society should NOT count on that study to be accurate for THEM. Now...the problem comes in determining if one is INSIDE the range of the study or OUTSIDE the range of the study.

Let's take breast-feeding as another example. Studies have [apparently] shown that women who breast-feed do NOT become pregnant until breast-feeding ceases [with certain exceptions.] *I* ended up breast-feeding two children at a time, and I had three friends who said to me, "Well, so much for breastfeeding being a method of birth control." If there's no KEY to WHO will be the exceptions in a study, the study is useless to those of us who will prove to be the exceptions.

ALL women's bones do NOT move. A friend of mine lost a portion of her cervical bones AND her tail bone.

Helen: Yes.

-- Anita (Anita_S3@hotmail.com), August 10, 2001.

Bigger babies have more stem cells! We pay top dollar.

-- (Dr Strangelove @ U.Med Center), August 10, 2001.

In the early 80's I was a research associate for a behavioral pharmacology research unit of a major university. This university had connections with the local municipal hospital. The hospital was located in one of the poorest areas of the city. We were studying addiction, and methods to prevent or alleviate it. My particular job was to investigate ways to convince people to quit smoking.

One study in particular will stay with me for the rest of my life. My boss noticed the high incidence of smoking among the (mostly) poor mothers-to-be who came to the OB/GYN clinic. He came up with the idea of a relatively inexpensive way of communicating with these women the risks of being a smoker while pregnant, and measuring how well this "intervention" worked.

I was set up with a desk next to the intake counter, where the women checked in with the clinic clerk. I was always in a white lab coat (it was required by the hospital anyway), so I blended in with the regular staff. After checking in and giving a urine sample, the women were sent over to me. I requested (and almost always got) a breath sample by having them blow up a 1-liter vinyl bag. I then asked them some general lifestyle questions, including whether or not they smoked, and if so, how many/day. After that, I sent them back to the waiting area to wait for their exam by the clinic doctors.

I had this cool little device, not much bigger that a desk calculator, that measured carbon monoxide in the breath sample. It was originally invented for firefighters, to determine CO breath levels in parts per million. It also made a very handy cigarette "breathalyzer." It was calibrated to CO level/# cigs smoked. With it, I could process the breath sample I had collected in less than a minute, identify who was a smoker, and roughly how much they smoked. I could also tell who was lying about it.

The intervention was this: I sent half of the identified mother-to-be a letter saying, in effect, that on her most recent clinic visit one of her medical tests indicated that she was most likely a cigarette smoker. The letter went on to explain the known and suspected risks of smoking while pregnant, including increased likelihood of low birth weight, the increased chance of placental abruption, and the increased chance of miscarriage.

I was at this clinic for nearly 2 years, following the progress of these women. They would normally come in every few weeks throughout their pregnancy. Some of them were even repeat "customers" with another pregnancy. I checked the delivery room list twice a day, and would visit the new mothers within hours of their delivery. With my trusty 1-liter breath bags, of course. I was usually a familiar face to these women by that time, and often would see the babies before the fathers did. Well, OK, many of these woman were single mothers, but that's not the point of this story.

The letter had a modest but statistically significant effect. Surprisingly, the greatest positive effect was with woman who lied about their smoking on the initial visit. Apparently, the result was: Uh Oh, Busted! They can tell by medical tests!

There was a small but still significant group who admitted smoking, and quit by their next clinic visit. There was some sense of job satisfaction, even if I had to keep it strictly to myself. This wasn't a double blind study. We didn't have the personnel.

The women who continued to smoke (in our study) did in fact have a statistically significant reduced average birth weight, and a high number of birthing complications (stillborn, abruption, and high blood pressure). We did not follow any of the mothers more than a couple of months past pregnancy; we didn't have funding for that.

The most saddening group for me personally were the ones who openly admitted to smoking, got the letter, showed no change in behavior over the course of their pregnancy, and ended up with problems. Since the relationship of smoking and pre- and post-natal problems was (and still is) statistical, rather than clearly causal, no one could point to smoking as the direct cause of the problems. I saw a wide spectrum of emotions in these women, from guilt to denial, blaming others for the problems, and total disbelief that smoking could have contributed to their pregnancy problems. Through it all, I was required by professionalism and the requirements of the research to appear to remain neutral and non-judgmental in my interviews. Whatever my feelings, if I didn't behave this way, how would we ever know that the outcomes weren't due to my subtle influence? We call this the Experimenter Effect, and we were trained to guard against it, but can never really be sure if it doesn't influence the outcome. It requires a very tight control over ones' emotions. If a researcher doesn't master this, he/she doesn't last long. The result can be a sometimes cold, unfeeling demeanor. No doubt I appeared that way to many of the participant in this study.

The main criticism of this study pointed out that woman who smoke may have had other poor health habits that contributed to the birth problems. This was a valid question, but my questionnaire of lifestyle habits did not support it. The only significant difference was in the smoking/nonsmoking category, verified by the CO breath levels.

Since I had, after a fashion, gotten to know these women, the hardest part of my job was to visit them in their hospital rooms for follow-up interviews soon after admittance for whatever medical problem they had. The one that affected me the most was a young woman, single, alone, working as a waitress, and smoking a pack and ½ a day. She had a placental abruption in the 7th month, and lost the baby. They had to give her a massive blood transfusion from the resulting blood loss the day before I saw her, and she was very lucky to survive. She blamed the doctors for not saving the baby. Then she blamed the paramedics for not getting there soon enough. Then she blamed me for not doing more about warning her about her smoking. I was shocked, since we naively assumed that no-one would connect me with the letter ( it was signed by a clinic doctor).

But we both knew who she was really blaming. I had come to know her that well. Her baby had become a statistic. And I asked to be re-assigned to another project the next day.

Please, if you are pregnant, don't smoke. If you are smoking, your unborn child is also smoking. Sure, with the current level of understanding, the increased risk to your child is statistical rather than directly causal. Your child may turn out OK, perhaps even superior. But you should ask yourself: at what level of risk in your direct control should you place your child? Smoking while pregnant is a roll of the dice, and your child has no voice in the outcome.

{rant off}

Spindoc'

-- Spindoc' (spindoc@no.way), August 10, 2001.

Spindoc, well said. I hope that the percentage of pregnant women who smoke has decreased in the last 20 years.

-- Lars (larsguy@yahoo.com), August 11, 2001.

Wow Spindoc'! I have some friends in the local maternity clinic who might let me put some copies of your post in their waiting rooms. May I have permission to do this?

-- helen (this@is.good), August 11, 2001.

helen,

PLEASE do. No permission is necessary, since I posted it on an open forum, but thanks for asking. I'll supply the reference if I must, but that would give away my ID. I'd rather not do that.

Thanks (you too Lars),

-- Spindoc' (spindoc@no.way), August 11, 2001.

Spindoc that was the most moving piece I've read in years. I too would like to share it at my clinic. However, I need to know who to attribute it to (I'm sure you understand). If you care to, would you email me at lghtml@yahoo.com?

Thanks.

-- (OB/GYN@clinic.net), August 11, 2001.

I have the feeling that some think I'm advocating that pregnant women should smoke. That was NOT my intent. My intent was to dishonor the last line of the first post, which said, "Women who smoked during pregnancy, for example, tended to have lightweight babies because they were born early."

The REST of this study's findings didn't receive ANY response [even from ME], but I think Matte was correct when he/she said, "Matte said research into the link between birth weight and intelligence was too sketchy to be useful for any practical or clinical application, but with time may prove valuable."

-- Anita (Anita_S3@hotmail.com), August 11, 2001.

Anita, 5-13 and 6-13 are FAR below normal birthweight.

I realize we all do stupid ignorant things when we are younger. I did many...many that I wish I could take back. I think you should at least admit that smoking during your pregnancies was one of those mistakes. It's almost as if you were bragging about it.

-- (cin@cin.cin), August 11, 2001.

I agree with you, Cin.

-- Anita (Anita_S3@hotmail.com), August 11, 2001.

Okay...I looked up this condition, symphysis pubis dysfunction, or dyastasis pubis, which is separation of pubic/pelvic bones due to the pregnancy hormones relaxin and progesterone, and baby's head during childbirth. Anita, it sounds like you had a questionable doctor, sorry to hear it too.

Here's a link if youre so inclined- I found it interesting myself

http://www.childbirth.org/articles/pubis.html

-- (cin@cin.cin), August 11, 2001.

Cin: I guess I should add something here. I agree with you that I poisoned my children by smoking while pregnant. HOWEVER, I STILL think that my small bone structure played a large role in their size. In each pregnancy, as it progressed, I found that my stomach had "moved" and had become smaller. It wasn't until each had "dropped" that I could eat full meals.

None of my doctors [and I had MANY] thought anything of my smoking. I've always been very honest and upfront with my doctors. The doctor who delivered my son [the last one] admonished me for not eating enough. He thought it was vanity that caused the weight LOSS in the final months. I'd never gained more than 12 pounds with ANY of them. I think he expected a small baby, but exclaimed, "He's a good- sized one" on the birthing. My SECOND was still breastfeeding at the time, and SHE was plump, although *I* was skinny as a rail.

I think the reason this article offended me was in the last line. My kids were all LATE. My second was 2.5 WEEKS late. My next-door neighbor saw me waddling out to the garage one morning and said, "Are you EVER going to have that baby?" I mumbled an "I dunno", but thought about how I sure was tired of walking like a duck.

-- Anita (Anita_S3@hotmail.com), August 11, 2001.

Um, Cin. I'm not sure I understand the information in your link. I know that MY bones moved, and I experienced NO pain in that movement. My friend's bones may/may not have moved, but [if they did], they didn't move ENOUGH.

All's well that ends well [as Jose once said.]

BTW, I was in an HMO during all three of my pregnancies, and I saw 4 or 5 doctors for each one.

-- Anita (Anita_S3@hotmail.com), August 11, 2001.

my point being...your pelvic bones (cervical bones are in your neck, perhaps youre confusing with cervix) dont break. They and ligaments, joints, etc, are loosened by pregnancy hormones, spefically for the purpose of childbirth, and that they can become separated.

-- (cin@cin.cin), August 11, 2001.

Would someone please hand me the smelling salts? bleh

Spindoc, I'll see if my clinic will allow your post to be displayed without using your name. If they like it but they need your name, I'll find a way to put you in touch with them, but only if YOU want that.

-- helen (privacy@first.then.altruism), August 11, 2001.

helen,

I still have a copy of one of the papers that came out of this study in my office at work, but it will have to wait until Monday for me to send you the reference. If you want it sooner, you might try a search using keywords: Smoking, Pregnancy, CO Levels, etc. I think the years were 1983-1985.

As with any research study of this nature, the requirements for patient confidentiality are severe,with very good reason.

These data were published nearly 20 years ago,in recognized medical and research journals. There is no excuse for medical and social work personnel to proclaim ignorance of it.

The human side that I presented on this forum is purely my point of veiw, as described by the one who actually collected the data.

helen, I will hold open an old email account to post the reference to this particular study for a short time:

spindoc_99_2000@yahoo.com

If you still need the reference, email me.

-- Spindoc' (spindoc@no.way), August 12, 2001.

Cin: I think we BOTH have our bones mixed up. Pointing out that the cervical bones were in the neck, however, reminded me of a neighbor whose pediatrician said at delivery, "Laurie, your baby is coming out backwards." She couldn't believe it and said, "Through my THROAT?"

I read up on symphysis pubis and diastasis pubis, and they're maladies that include pain and a need for bedrest. I understand that the coxal bones of the pelvic girdle MEET at the pubic symphysis [also called the sub-pubic-arch], but I need to research further to get information on HOW the coxal bones separate without estranging themselves from the pubic symphysis [thereby causing this malady.] I think even your own link said that separation of the pubic symphysis only occurred in one of 30,000 cases [or something like that.]

I got out my baby book to see how much I weighed at birth. I was under 7 lbs. myself, and the third-born after two boys. My mom smoked with my second brother [I don't know if she did with the first], but my dad told her he didn't like to see a nursing woman smoking, so she quit smoking while nursing him. He was one of those BIG babies, and turned out to be a big grownup. Boys ARE [traditionally] bigger at birth. MY son turned out to be tall with big bones, while his sisters are smaller with finer bones, like mine. Genetics, gender, and birth order play a large role in birth weight, as well as the stupid things mothers do while pregnant.

-- Anita (Anita_S3@hotmail.com), August 12, 2001.

Anita, the standard deviation for length of pregnancies is supposed to be 16 days. So 2 1/2 weeks extra is only a bit more than one standard deviation longer than normal; puts you around the 87th percentile for length of pregnancy.

-- dandelion (golden@pleurisy.plant), August 13, 2001.