Theme 8: Feelings of loss enveloped the mothers as they dwelled on their
relationships with their children. [This theme may be most consistent with the
arguments presented for negative affect in section one.]
Theme 9: Striving to minimize the negative effects of postpartum depression on their
children, mothers attempted to put their children’s needs above their own. [In the
same way that people can continue with an activity even though it causes them
physical pain, they can decide to continue an activity that causes psychological pain.
This theme also suggests that mothers are “aware” of the tradeoff between investing
in themselves and investing in their infants, a core concept of PI theory.]
If PPD is, in part, an adaptation to motivate women to reduce investment in their offspring
under certain conditions, then women who did not want to be pregnant in the first place should
be at higher risk for PPD. This is in fact the case. Field et al. (1985) found that an affirmative
prepartum response to questions like “was your pregnancy unplanned?,” “do you regret being
pregnant?,” “can you say that you do not desire to have a child?” (in addition to other
questions—see figure 2) significantly distinguished women with PPD from those without.
Similarly, Campbell et al. (1992) found that not being happy about the pregnancy distinguished
women with PPD from those without. Finally, Kumar and Robson (1984) found that women
with PPD had significantly more often considered an abortion.
While PPD is defined primarily by affective and cognitive symptoms, if it is an adaptation to
reduce investment in offspring, then it must have, on average, actually have modified ancestral
mothers’ behavior in a way that prevented them from attaching to or investing in their infants.
Beck’s meta-analysis (1995) of 19 studies on the effects of PPD on mother-infant interactions
(total number of dyads = 829) indicates that PPD has a moderate to large negative effect on
maternal-infant interaction. In these studies, observers who are blind to the mothers’ depression
status rate her interaction with her infant. Mothers with PPD are observed to have significantly
increased disengagement, negative affect, flatness of affect, irritation, tenseness, annoyance, and
intrusiveness towards the infant on the one hand, and significantly less warmth, delight, positive
regard, sensitivity, activity, contented facial expressions, imitative behaviors, contingent
responses, and game-playing on the other. In addition to exhibiting more negative emotions and
fewer positive emotions towards their infants, mothers with PPD are less responsive and less
sensitive to infant cues, have a less successful maternal role attainment, and have infants that are
less securely attached (Beck, 1995; Beck, 1996b; Cohn et al., 1990; Cohn et al., 1991; Field & et
al., 1985; Fowles, 1996; Hoffman & Drotar, 1991; Murray, 1991; Murray & Cooper, 1996). By
being less responsive and less sensitive to infant cues, mothers with PPD are clearly mothering
less.
The above studies indicate that mothers with PPD are ambivalent about their pregnancies,
have difficulty emotionally investing in, and interacting with, their infants, and are less sensitive
and responsive to their infants. These manifestations of PPD strongly support the “loss of
interest” and “reduced investment” in the infant predicted by the defection hypothesis.
Whereas loss of interest in the infant has a straightforward interpretation in the context of PI
theory, loss of interest in virtually all important life activities presents a more difficult though
perhaps more important theoretical problem, and possible adaptive functions for this symptom
vis-a-vis evolutionarily significant risks and dangers of the puerperium will be offered in the
next section. These more speculative functions generalize the hypothesis to renegotiation or
defection from relations with the father and family members in an attempt to solve two
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