Table 2.

Interaction between gestational duration and fetal growth in relation to risk of intellectual disability

Gestational durationa/weight-for-gestational age categoryb	Odds ratioc	95% CI		p	n (%)d	Ne	Percentage of the cohort (%)
		Lower	Upper
Preterm/small	3.77	2.97	4.84	< 0.001	73 (3.8)	1935	0.4
Preterm/appropriate	2.24	2.01	2.51	< 0.001	380 (2.1)	18,256	3.7
Preterm/large	2.36	1.81	3.07	< 0.001	61 (2.3)	2681	0.5
Term/small	1.88	1.73	2.05	< 0.001	731 (1.8)	41,579	8.3
Term/appropriate	1.00				3008 (0.9)	352,016	70.5
Term/large	1.06	0.95	1.18	0.27	402 (0.9)	44,620	8.9
Post-term/small	2.29	1.83	2.85	< 0.001	85 (2.2)	3822	0.8
Post-term/appropriate	1.11	0.98	1.25	0.10	292 (1.0)	30,840	6.2
Post-term/large	1.22	0.87	1.69	0.24	37 (1.0)	3872	0.8

^aPreterm was defined as birth < 37 completed weeks of gestation. Term birth was defined as birth between 37 and 41 completed weeks of gestation. Post-term birth was defined as birth at ≥ 42 completed weeks of gestation

^bFetal growth categories were defined as small-for-gestational age [in the lowest decile of the gestational age-specific birthweight distribution], appropriate-for-gestational age [in the 11th to 90th decile of the gestational age-specific birthweight distribution] and large-for-gestational age [in the upper decile of the gestational age-specific birthweight distribution]

^cPopulation-level associations were estimated using a generalized estimating equations model with a logit link, and adjusted statistically for year of birth, child sex, parity, gestational hypertension or preeclampsia, gestational diabetes, maternal and paternal age, maternal and paternal psychiatric history, maternal and paternal country of birth, family disposable income quintile at birth, and parental educational attainment at birth

^dNumber and percentage of ID cases within gestational duration/fetal growth category

^eNumber of observations within gestational duration/fetal growth category

^fN = 499,621