Antenatal Growth and Later Disease?

[Guest guest]

Birth size and shape are commonly used as indicators of foetal growth.

Epidemiologic studies have suggested a relationship between birth size and

the risk of developing cardiovascular disease in later life. Certain " growth

phenotypes " have been linked to the development of certain components of

cardiovascular disease, particularly babies who display disproportional

growth in utero. The following study showed that the low correlations

between antenatal measures and birth size suggest that it is unwise to

ascribe birth shape phenotypes to adverse events at any particular stage of

gestation. The weak relationship also suggests that routine antenatal scans

around 30 wk of gestation to predict growth problems are unlikely to be of

benefit in the majority of cases.

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Pediatr Res 2002 Aug; 52(2): 263-268

Intrauterine Growth and its Relationship to Size and Shape at Birth.

Hindmarsh PC, Geary MP, Rodeck CH, Kingdom JC, Cole TJ.

Birth size and shape are commonly used as indicators of fetal growth.

Epidemiologic studies have suggested a relationship between birth size and

the risk of developing cardiovascular disease in later life. Certain " growth

phenotypes " have been linked to the development of certain components of

cardiovascular disease, particularly babies who display disproportional

growth in utero. These observations are based on retrospective analysis of

historical data sets. If the " Fetal Origins of Adult Disease " hypothesis is

to be generalisable to the present day, then it is essential to establish

whether these " growth phenotypes " exist within the normal distribution of

birth size. The UCL Fetal Growth Study is a prospective study of antenatal

fetal growth assessed by ultrasound at 20 and 30 wk gestation in 1650 low

risk, singleton, white pregnancies. Measures of birth size were obtained and

analyzed by principal components to explain shape at birth. Birth measures

were also related to antenatal growth measurements to determine the strength

of ultrasound evaluation in determining subsequent growth.

There was significant sexual dimorphism in all measures at birth, with males

heavier, longer, and leaner than females. From 20 wk of gestation onwards,

males had a significantly larger head size than females. Parity, maternal

height, and body mass index were important determinants of birth weight.

Cigarette smoking influenced birth weight, length, and head circumference but

had no effect on placental size.

Principal component analysis revealed that proportionality was the

predominant size/shape at birth (55% of variance explained). A further 18%

of variance was explained by a contrast between weight, head circumference,

and length versus three skinfolds. Anthropometric measures as assessed by

ultrasound at 20 and 30 wk gestation were poor predictors of birth length,

weight, and head circumference (adjusted R(2) 18, 40, and 28% at 30 wk

gestation scan, respectively). These predictions were not improved by includi

ng growth patterns between 20 and 30 wk.

There is sexual dimorphism in a number of anthropometric measures at birth

and in utero. These sex differences are important determinants of body size

and shape. In a low risk population delivering at term, body shape was

largely determined by proportionality between anthropometric measures. The

low correlations between antenatal measures and birth size suggest that it is

unwise to ascribe birth shape phenotypes to adverse events at any particular

stage of gestation. The weak relationship also suggests that routine

antenatal scans around 30 wk of gestation to predict growth problems are

unlikely to be of benefit in the majority of cases.

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Dr Mel C Siff

Denver, USA

http://groups.yahoo.com/group/Supertraining/