The genetics of feto-placental development: A study of acid phosphatase locus 1 and adenosine deaminase polymorphisms in a consecutive series of newborn infants

Table 5 Correlation between birth weight and placental weight in relation to ADA₁ phenotypes.

	ADA₁ phenotypes
Sample	ADA₁1		(ADA₁2/1+ADA₁2)
	r	p*	r	p*
All subjects	0.289	0.000	0.552	0.000
Smoking
Yes	0.275	0.003	0.484	0.036
no	0.288	0.000	0.589	0.000
Significance of difference p**	0.300		0.150
Maternal age (yrs)
≤28	0.104	0.181	0.679	0.000
>28	0.559	0.000	0.341	0.120
Significance of difference p**	0.000		0.000
Gestational age (wks)
≤37	0.292	0.187	0.922	0.078
>37	0.286	0.000	0.560	0.000
Significance of difference p**	0.900		0.350
Birth order
1	0.449	0.000	0.572	0.001
≥ 2	0.212	0.009	0.543	0.003
Significance of difference p**	0.000		0.700
Sex
male	0.268	0.000	0.359	0.078
females	0.344	0.000	0.692	0.000
Significance of difference p**	0.000		0.000

Significance of difference between correlation coefficients has been calculated according to Snedecor and Cochran. p* refers to significance of correlation coefficient. p** refers to significance of difference between the two classes. For "All subjects" the difference of correlation coefficients between ADA₁1 and (ADA₁2/1+ADA₁2) i.e. 0.289 vs 0.552 is statistically significant: p = 0.04.

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