Table A2.

Descriptive Statistics for Background Characteristics in ALSPAC

Variable	Description	Mean	Std. Dev.	N
Mother’s age	Maternal age in years	28.27	4.850	10999
Child: girl	0/1 indicator for female birth	0.485	0.500	11428
Lone Parent	0/1 indicator for mother being a lone parent	0.070	0.255	8576
# siblings	Number of siblings of cohort child	0.871	0.958	9009
Locus of control	Mother’s locus of control	−0.033	0.991	8605
CCEI Trimester 2	Crown-Crisp Experimental Index, Trimester 2	13.29	7.583	9279
EPDS Trimester 2	Edinburgh Postnatal Depression Score, Trimester 2	6.759	4.757	9717
Mother is happy	Variable ranging from 1–4 with 4 being most happy	3.260	0.805	6733
Mother is content	Variable ranging from 1–4 with 4 being most content	3.100	0.908	6692
Maternal education	Variable ranging from 1–4; 4 is highest education	2.297	0.926	10372
Social class	Variable ranging from 1–6; 6 is lowest social class	3.021	1.320	9008
Mother is employed	0/1 indicator for mother being employed	0.480	0.500	8531

Notes: Maternal educational includes four indicators: less than ordinary (O) level, O-level only, advanced (A) level that permits higher educational study, and having a university degree. We use the standard (reversed, so that higher values correspond to higher social classes) UK classification of social class based on occupation (professional (I), managerial/technical (II), non-manual skilled (IIInm), manual skilled (IIIm), semi-skilled (IV) and unskilled (V)). EPDS (Edinburgh Postnatal Depression Score) and CCEI (Crown-Crisp Experimental Index) aim to capture aspects of maternal mental health. EPDS indicates to what extent the mother is at risk of perinatal depression; CCEI captures a broader definition of mental health, measuring general anxiety, depression and somaticism. Higher scores mean the mother is more affected.