Birth body weight to length ratio

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I'm off the chart. I weighed around 1600g when I was born. Although I measured 47cm.

I don't know my length, but I was born 5 weeks early at 1360g. Worth noting also, I'm extremely short as an adult (just under 5').

Not in my family. We have nobody short or tall. All babies were born about average in weight and height. OK I was born 6 weeks early, but weighed 7 lbs 3 oz (which was at about 50% for full term Chinese babies). If I made it to due date I'd be over 9lbs for sure. My autistic boys were nearly 8lbs and 8.5 lbs. It mostly depends on the genetics in the mother's family. DH comes from a family of tiny babies, he was born full term at a bit over 5 lbs. Obviously his family's genetics didn't influence my pregnancies.

In my home only my brother had birth weight above 20th percentile. I am interesting what is the probability that 4 of 5 randomly chosen people would have birth weight below 20th percentile. Both parents have it.

Let's count the product of birth weight percentiles for my family. I have about 0,3, my sister about 9, my father about 12, mother about 16, brother - 69,5.

0,3*9*12*16*69,5=36 028,8
50*50*50*50*50=312 500 000
312 500 000/36 028,8=8 673,61666223

It is about 8670 times lower than 50 to fifth power.

From Polish birth weight to length percentile I may conclude that my percentile would be about 0,3, my sister's about 5 and my mother's about 2 (maybe even less).

The product of them is 0,3*2*5 = 3. It is very low, maximum is 100*100*100=1000 000, average 50*50*50 = 125 000. So it is about 41 667 times below the average...

In the term of birth weight according to Polish work which I presented earlier (when we assume normal distribution), my mother's birth weight percentile would be about 12, my sister's about 8 (or 7?), mine - about 0,4.

The product of them is 12*8*0,4=38,4. About 3255 times below the average.

And for me it may looks that my mother is NT with some "acoric" influence. My sister is more similar to mother than to me, but for me she looks corcerningly similar to me ("somewhat strange" social and emotional features), like someone who have something which I could name as "neurotypicalised acoria" or "polymictoidia" ("neurodiversity" may look as dominant factor in her case, alhough superficially she look rather "normal"). I have acoria and polymixia.

It is good for me that supposed results of my hypotrophy are so mild. I am relatively versatile intellectually and somatically. But I suppose that I will be not able to any kind of marriage in my entire life because of my disorders. But I have higher education and may have work. I am "pathologically asthenic" and may feel as someone with serious handicap sometimes.

Is (low) birth weight something genetic? And is relation of birth weight to birth length something which can be determined genetically?

Siblings of my father had birth weight above 3000 g, they have Master's degree now and were younger than my father. I do not know about their body length. Appear to be not "aucorigic". Their older brother appear as less neurotypical person to me, but still not an Aspie.

Father had 2800 g. Mother also. Mother had 56 cm, which means really low birth weight-length percentile (about 2nd). Both parents had birth weight below 17th percentile. 34.6020761246 = (1/0,17)^2. Probablility of the situation that two randomly chosen parents would have both birth weight percentile below 17 should be about 1 : 34,5.

My sister had 2650 g, which is about 9th percentile. She and both parents had birth weight below 17th percentile. (1/0,17)^3 = 203.541624262. It is quite large number which means that the probablility that three randomly chosen people (who are: child, father and mother) would have birth weight below 17th percentile is even below 1 : 200. It is quite rare situation. My brother had 3600 g, which is about 70th percentile, he does not mean this "criterium". I and my sister meet it. The probablity that the child, mother and father woyld have birth weight below 20th percentile is 1 : 125 - still large number!

Interesting text:

http://www.ncbi.nlm.nih.gov/pubmed/20819986

Birth weight, schizophrenia, and adult mental disorder: is risk confined to the smallest babies?

Abstract

CONTEXT:
Studies linking birth weight and mental illness onset are inconclusive. They have primarily focused on the World Health Organization low birth weight threshold (2500 g) and schizophrenia. To our knowledge, low birth weight per se has not been conclusively linked with schizophrenia risk and specificity of the effect to birth weight below the standard threshold or to particular psychiatric diagnoses has not been demonstrated.
OBJECTIVES:

To examine whether (1) low birth weight (<2500 g) is associated with increased risk for adult schizophrenia; (2) risk extends into the normal weight range; and (3) risk is confined to schizophrenia or linked to other adult mental illnesses.

DESIGN:
Population-based cohort study.

SETTING:
Sweden and Denmark.

PARTICIPANTS:
Singleton live births in Sweden (1973-1984) and Denmark (1979-1986) (N = 1.49 million). Births were linked to comprehensive national registers of psychiatric treatment, with follow-up to December 31, 2002 (Sweden), or to June 30, 2005 (Denmark). There were 5445 cases of schizophrenia and 57 455 cases of any adult psychiatric disorder.
MAIN OUTCOME MEASURE:

Crude and adjusted odds ratios for birth weight less than or more than 3500 to 3999 g in consecutive 500-g strata (from 500-1499 g to > or =4500 g) for schizophrenia, any psychiatric diagnoses, and specified psychiatric diagnoses.

RESULTS:
Schizophrenia was associated with birth weight less than 2500 g. The association was not restricted to birth weight less than 2500 g and there was a significant linear trend of increasing odds ratios with decreasing birth weight across the birth weight range. This was mirrored for any psychiatric diagnosis and for each of the categories of psychiatric disorder.

CONCLUSIONS:
Findings suggest there is an association between birth weight and adult mental disorder, but there is no indication this effect is specific to birth weight less than 2500 g or to schizophrenia. Future research should explore common disorder-specific mechanisms that may link birth weight to development of psychiatric disorder in adulthood.

I suppose that in my family there is a sort of relation between birth weight and mental "typicality". I had 2150 g and large body length for this weight and was born on time and had 10 points in Apgar scale. I was diagnosed with Asperger syndrome and schizotypal disorder. My sister had 2650 g and is somewhat "strange" to me. My parents had 2800 g and are in my opinion "unbalanced" emotionally. Brother had 3600 g and looks the most "neurotypical" for me.

It is interesting how often low birth weight occurs in people with PDDs and autism spectrum disorders. Also how often it occurs in cases of "nonverbal learning disorder"?

It is interesting if low birth weight (in comparison to birth weight) also is somewhat correlated to mental health problems. In my family I, my mother and sister had rather low birth weight in comparison to birth weight (especially I). My brother had normal birth weight and length.

There is also something such as ponderal index: http://en.wikipedia.org/wiki/Ponderal_index

I do not know what was my length from crown to heel at birth.

But I calculated (something like) PI tomorrow for some people (such as I and my mother), using the formula:
((birth weight (in grams))*100)/(birth body length)^3
I subtracted 6 cm from birth weight from my health certificate and the result was: (2150*100)/(47*47*47)=215000/103823= about 2,07 (significantly low)
For my sister (2650 g, 53 cm (47 cm)): 265000/103823 = about 2,55 (not so bad)
For my brother (3600 g, 57 (51 cm)): 360000/132651 = about 2,71 (normal)
For my mother (2800 g, 56 cm (50 cm)): 280000/125000 = about 2,24 (low!)
For my mother's brother (3750 g, 53 cm (47 cm), my grandmother said that he was born two weeks before term): 375000/103823 = about 3,61 (really high!)
For example, if someone has 3000 g and 60 cm (54 cm), it would be: 300000/157464 = about 1,905 (very low).
For a newborn who has 2100 g and 46 cm it would be: 210000/97336 = about 2,16 (low)
For a newborn who has 900 g and 35 g it would be 90000/42875 = about 2,1 (significantly low)

Link to the polish publication abut birth weight-length relations (again): http://www.wskfit.pl/PDF/artykuly/14005.pdf.

On this chart "average" weight for boy who has body length 53 cm (but measured not according to WHO standards) on birth is about 3200 g. So my "ponderal index" would be (assuming that WHO length is 47 cm): 320000/103823 = about 3,08

For a boy with birth weight 4300 g and birth length 61 cm (55 cm?) - it is about 50th percentile on Polish weight-length chart - it would be: 430000/166375 = about 2,58 (about 0,5 lower than for boy with 53 cm (47 cm?) and 3200 g).

I think that the formula [(birth weight (in grams))*100)/(birth body length)^3], which I used above, is not so useful because results for longer babies from the same percentile on weight-lenght chart are significantly lower than for shorter ones. The formula used for newborns which can be found in Wikipedia is other - (birth weight)/(length from crown to heel)^3)

Maybe counting BMI at birth will be better? For me (after subtracting 6 cm from 53 cm) it would be 2,150/0,2209= about 9,73. For my sister - 2,650/0,2209= about 12. For my brother - 3600/0,2601= about 13,84. The result of my sister is closer to the result of my brother. BMI below 10 for on-term newborn appears to be really low. What would be for a newborn who has 3000 g and 54 cm? 3,000/0,2916= about 10,3. It is somewhat higher than in my case. But "ponderal index"(?) for such a newborn in my previous post was somewhat lower than for me.

i dont know how im supposed to know that, but I was very heavy and chubby.
that quickly changed though.

An interesting publication about weight-length relations of newborns:

http://www.scielo.br/scielo.php?script=sci_arttext&pid=S1516-31802003000400002

Regression lines for weight/length distribution at birth with 10th and 90th percentiles:



Histogram frequency for weight/length (W/L) index [includes pre-term infants]:

Assuming that birth weight measured in Poland is 6 cm larger than "real" birth weight for a newborn, for me and some of my family members the results would be:

- for me: 2150/47=45,74 (significantly below 10th percentile)
- for my sister: 2650/47=56,38 (very close to 10th percentile, just about 0,05 above it)
- for my mother: 2800/50=56 (really slightly below 10th percentile, she was born on time)
- for my brother: 3600/51=70,59 (between 50th and 90th percentile)
- for the brother of my mother: 3750/47=79,79 (above 90th percentile, although his mother said that he was born 2 weeks before the term (gestational age was 36 weeks(?)))

It looks that it is highly possible that (at least for many) we should subtract less than 6 cm from birth body length from health certificate (at least in Poland). When we subtract 6 cm from length from HC, we would often receive much higher percentile in http://www.infantchart.com/infantweightlength.php than in the charts from http://www.wskfit.pl/PDF/artykuly/14005.pdf.

In Polish chart a girl with 53 cm and 2650 g is almost on 3rd percentile (very low). But in infantchart.com, when we subtract 6 cm from 53 cm, we receive 26,8th percentile for 2650 g. To receive 3rd percentile for girl who weighs 2650 g on birth, body length has to be about 48,8 cm - 48,9 cm. Only 4,1 - 4,2 cm should be subtracted, not 6 cm. A boy with 3750 g and 53 cm is between 90th and 97th percentile (about 94th?) on Polish chart, but in infantchart.com 47 cm and 3750 g will give 99,9th percentile. To receive 94th percentile on infantchart.com, we should subtract just 3,4 cm from 53 cm (for a boy, 49,6 cm and 3750 g gives 94,1th percentile).