Effects of trimester-specific and total gestational weight gain on children’s anthropometrics

Table 2 Effects obtained from structural equation modeling

Effects on BMI z-scores (i. e. std) per GWG (kg/week)
Period	Direct effect ± stderr	Indirect effect ± stderr	Total effect ± stderr (estimated via OLS regression)
t1	0.105 ± 0.060*	0.104 ± 0.043*	0.208 ± 0.042*
t2	0.255 ± 0.116*	0.241 ± 0.100*	0.498 ± 0.064*
t3	0.002 ± 0.098	0.199 ± 0.083*	0.198 ± 0.056*
Total gwg	0.608 ± 0.252*
Effects on waist circumference (cm) per GWG (kg/week)
Period	Direct effect ± stderr	Indirect effect ± stderr	Total effect ± stderr (estimated via OLS regression)
t1	0.538 ± 0.254*	0.176 ± 0.181	0.714 ± 0.179*
t2	1.644 ± 0.489*	0.408 ± 0.421	2.055 ± 0.268*
t3	0.308 ± 0.413	0.337 ± 0.347	0.641 ± 0.237*
Total gwg	1.03 ± 1.062

The rows in this table represent the trimester-specific effects of GWG broken down to the direct part and the part mediated via total GWG. Significant (p < 0.05) are marked by *. The first column can be interpreted longitudinally over the whole pregnancy period: a mother gaining additional weight of 1 kg/week in t1 and t2 and compensating this gain in t3 arriving at no additional total GWG attains the direct effects of t1 and t2 (0.105 + 0.255 = 0.36) accounting for an increment in offspring’s BMI of 0.36 z-scores, but avoids the effect of total GWG. A mother continuing to gain additional weight of 1 kg/week in t3 would attain the direct effects of t1 – t3 plus the effect of total GWG (0.105 + 0.255 + 0 + 0.608 = 0.97).

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