Table 3.

Univariable analysis of continuous early life variables and hand preference.

TRAIT	N	p-value	Note	Effect on logit Right Hand preference
Year of birth	421,667	1.0E-30	Increase ~ 0.7percentage -points per decade	−0.007 yr−1
Birthweight	231,155	0.0009	Left-handers are ~26 g lighter on average	0.035 kg−1
Cosine(month)	421,667	0.004	See Figure S4	0.022