We identify the causal effect of mothers' mental health during early -  and soon after pregnancy on a range of child psychological, socio-emotional and cognitive outcomes measured between ages 4-16. Results suggest a negative effect on children's psychological and socio-emotional skills in early childhood, but these effects fade-out between the ages of 11-13. We find no significant effect on cognitive outcomes. The fade-out of effects may be partly explained by compensatory behaviour of parents, as we find that mental health during or soon after pregnancy raises breastfeeding and improves measures of interaction between mother and child.