Objective
The association between maternal psychological state during pregnancy and birth outcomes is well established. The focus of previous studies has been on the potentially detrimental consequences of maternal stress on pregnancy and birth outcomes, particularly shortened gestation and increased risk of preterm birth. Despite a growing literature linking positive affect with favorable health outcomes this construct has received little attention in the context of pregnancy. Therefore, in the current study, we tested the hypothesis that maternal positive affect during pregnancy is associated with beneficial consequences in terms of increased length of gestation and reduced risk of preterm birth above that of the absence of stress.
Methods
In 169 pregnant women maternal positive affect and perceived stress were serially assessed at 15.2±0.9 weeks (T1; mean ± SD), 19.7 ± 0.9 weeks (T2) and 30.7 ± 0.7 weeks (T3) gestation. Pregnancy and birth outcomes were abstracted from the medical record.
Results
Higher maternal positive affect and a steeper increase in maternal positive affect over pregnancy were positively associated with length of gestation (p < .05) and reduced risk of preterm delivery (p < .01), whereas maternal perceived stress was not significantly associated with shorter length of gestation (p > .10).
Conclusions
These findings suggest that maternal positive affect may be beneficial for outcomes related to the length gestation, and that this effect cannot be accounted for by the lower stress levels associated with higher positive affect. Interventions to increase maternal positive affect may be beneficial for fetal development.
The belief that a mother's emotional state during pregnancy may influence the development of her fetus has persisted across time and culture. This has stimulated research on maternal psychological state during pregnancy and various pregnancy and birth outcomes. One of the most consistent findings in this literature is the observed association between higher levels of maternal psychological stress during pregnancy and shortened length of gestation and increased risk of preterm birth [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11], [12], [13] and [14]. Although a growing body of literature has examined and demonstrated that positive affect is independently associated with more favorable health outcomes [15] this question has received relatively little attention in the context of pregnancy and birth outcomes.
Several studies, for example, have shown associations between positive affect and improved cardiovascular function, with positive affect being related to accelerated recovery from cardiovascular reactivity [15], [16] and [17], decreased blood pressure in ambulatory assessments [18] and [19], and elevated parasympathetic activation [20]. Positive affect also has been linked to lower cortisol concentrations over the course of the day [21] and [22] and to higher antibody responses to hepatitis B vaccination [23].
One of the few studies on positive maternal affect during pregnancy found that women with stronger personal resources (mastery, self-esteem, optimism) had higher birth weight babies, even after controlling for the effects of gestational age at birth, psychosocial stress, and other variables [4]. Another study reported that maternal dispositional optimism was related to higher infant birth weight [24]. A more recent study described associations of positive state of mind and emotional stability in the immediate post-partum period with having experienced a normal delivery, however, positive affect was assessed in the immediate post-partum period and the positive delivery experience may have caused the higher positive affect in these women and not vice versa [25]. Thus, there is some preliminary evidence suggesting that maternal positive affect may be beneficial in the context of pregnancy and birth outcomes.
The objective of the present study was to assess the relationship between positive affect and length of gestation. We hypothesized that high maternal positive affect would be associated with longer length of gestation, and that this association would be significant even after controlling for the effects of maternal stress levels.
