Exploring the causal effect of maternal pregnancy adiposity on offspring adiposity: Mendelian randomisation using polygenic risk scores

Table 1 Characteristics of the mothers and offspring in ALSPAC and BiB

	ALSPAC				BiB (WE)				BiB (SA)
	Mean	SD	N	Female offspring (%)	Mean	SD	N	Female offspring (%)	Mean	SD	N	Female offspring (%)
Maternal BMI (kg/m²)	23.0	3.8			26.9	6.0			25.8	5.5
Maternal age (years)	29.3	4.5			27.4	6.0			28.8	5.0
Birth weight (z score)	0.10	0.95	5085	50.5	− 0.05	0.97	1992	47.9	− 0.56	0.92	2262	47.9
Gestational age (weeks)	39.6	1.7			39.4	1.6			39.1	1.5
1-year weight for length percentile^a	0.64	0.27	4838	50.6	0.61	0.28	1798	47.8	0.48	0.30	2023	48.1
Age at measurement (years)	0.9	0.2			0.8	0.3			0.8	0.3
4-year BMI (z score)	0.46	1.05	4670	50.2	0.50	0.97	1339	48.6	0.10	1.21	1566	48.5
Age at measurement (years)	4.1	0.7			4.5	0.7			4.5	0.7
10-year BMI (z score)	0.26	1.12	4476	51.3
Age at measurement (years)	9.9	0.5
15-year BMI (z score)	0.30	1.11	4112	51.7
Age at measurement (years)	15.0	0.8

SA South Asians, WE White Europeans, SD standard deviation, z score: sex- and gestational age-adjusted standard deviation score (UK-WHO Growth Reference [88]). ^aSex-adjusted percentile calculated using the WHO Child Growth Standards [89]. All z scores and percentiles were calculated via the zanthro Stata package [90]. Data for absolute values (as opposed to z scores) are presented in Additional file 1: Supplementary information S18

ISSN: 1741-7015