Mental illness either in pregnancy or postpartum has significant and potentially serious long-term deleterious outcomes, not just for the woman but also for her entire family, and in particular, for her infant.

The immediate effects of depression, anxiety and stress during pregnancy include an increase in the rate of pre-term delivery, lower APGAR scores, lower birth weights and smaller head circumference (Dayan et al., 2002; Hedegaard et al., 1996; Lou et al., 1994; Orr & Miller, 1995; Orr et al., 2002; Steer et al., 1992; Wichers et al., 2002). It is as yet unclear whether these effects are related directly to physiological changes occurring in the depressed mother, in particular those associated with stress responses along the hypothalamic-pituitary-adrenal axis (Dieter et al., 2001; Gitau et al., 2001; Lockwood, 1999; Sandman et al., 1997; Weinstock, 1997); or indirectly as a result of poor health behaviours (Lindgren, 2001; Zuckerman et al., 1989).

The long-term adverse effects of prenatal depression, anxiety and stress on the offspring have been known for some time and are well documented. For example, newborns of depressed mothers consistently show behavioural differences and developmental problems when compared to infants born to non-depressed mothers (Grace et al., 2003; Jones et al., 1998; Lundy & Field, 1996; Lundy et al., 1999; Martins & Gasffan, 2000; Weinberg & Tronick, 1998).