Biological factors for postnatal distress

Since both anxiety and depressive symptoms – the most characteristic signs of distress - have been found to have a negative effect on the mother’s wellbeing and the newborn’s development (Beck, 1998), a large body of research from different perspectives has focused on building explanatory models and describing risk factors that may explain the development of this phenomenon.

From a biochemical perspective, the intense physiological and hormonal changes observed across pregnancy and the postpartum period have been pointed out as a possible cause for the onset of postnatal distress. This hypothesis is based on the findings about the interaction between ovarian hormones - such as progesterone and estrogen – and central nervous system neurotransmitters related to mood disorders (i.e. serotonin and GABA).

Studies have usually focused on hormones such as progesteron, estrogene, cortisol, and prolactine. During pregnancy these hormones increase their levels progressively to reach levels that are hundred times higher than those found in non-pregnant women. This high concentration decreases intensively after delivery and the withdrawal of the placenta - with the exception of prolactine, which remains high in lactating women - therefore it has been hypothesized that depressed mood in the early postpartum period might be related to the sudden drop of hormonal levels (Harris, 2010).
Several studies have been conducted on this topic, and although hormonal fluctuation has provided a suitable explanation for the aetiology of PPD in some cases, it has failed to do so in many others; which raise questions about individual differences in the responses to both increase and reduction of hormonal levels. In effect several authors (Bloch, 2000; Harris et al, 2010, Kammerer et al, 2009; Klier et al, 2007) have suggested that women who develop postnatal depression may have certain vulnerability and/or high responsiveness to hormonal changes, which would put them at higher risk for developing mood disorders.
The mixed and inconclusive nature of current findings on this topic highlights the complex dynamics within the endocrine system and its intricate relation to the neural structures involved in mood regulation and mood disorders; and raises the question about the role of other factors - such as psychosocial aspects - that may play a role in this phenomenon.