Jennifer Hahn-Holbrook

Biological and psychosocial predictors of postpartum depression: systematic review and call for integration.

Postpartum depression (PPD) adversely affects the health and well being of many new mothers, their infants, and their families. A comprehensive understanding of biopsychosocial precursors to PPD is needed to solidify the current evidence base for best practices in translation. We conducted a systematic review of research published from 2000 through 2013 on biological and psychosocial factors associated with PPD and postpartum depressive symptoms. Two hundred fourteen publications based on 199 investigations of 151,651 women in the first postpartum year met inclusion criteria. The biological and psychosocial literatures are largely distinct, and few studies provide integrative analyses. The strongest PPD risk predictors among biological processes are hypothalamic-pituitary-adrenal dysregulation, inflammatory processes, and genetic vulnerabilities. Among psychosocial factors, the strongest predictors are severe life events, some forms of chronic strain, relationship quality, and support from partner and mother. Fully integrated biopsychosocial investigations with large samples are needed to advance our knowledge of PPD etiology.

Maternal Defense Breast Feeding Increases Aggression by Reducing Stress

Mothers in numerous species exhibit heightened aggression in defense of their young. This shift typically coincides with the duration of lactation in nonhuman mammals, which suggests that human mothers may display similarly accentuated aggressiveness while breast feeding. Here we report the first behavioral evidence for heightened aggression in lactating humans. Breast-feeding mothers inflicted louder and longer punitive sound bursts on unduly aggressive confederates than did formula-feeding mothers or women who had never been pregnant. Maternal aggression in other mammals is thought to be facilitated by the buffering effect of lactation on stress responses. Consistent with the animal literature, our results showed that while lactating women were aggressing, they exhibited lower systolic blood pressure than did formula-feeding or never-pregnant women while they were aggressing. Mediation analyses indicated that reduced arousal during lactation may disinhibit female aggression. Together, our results highlight the contributions of breast feeding to both protecting infants and buffering maternal stress.

Parental Precaution: Neurobiological Means and Adaptive Ends

Humans invest precious reproductive resources in just a few offspring, who remain vulnerable for an extended period of their lifetimes relative to other primates. Therefore, it is likely that humans evolved a rich precautionary psychology that assists in the formidable task of protecting offspring. In this review, we integrate precautionary behaviors during pregnancy and postpartum with the adaptive functions they may serve and what is known of their biological mediators, particularly brain systems motivating security and attachment. We highlight the role of reproductive hormones in (i) priming parental affiliation with young to incentivize offspring protection, (ii) focusing parental attention on cues of potential threat, and (iii) facilitating maternal defense against potentially dangerous conspecifics and predators. Throughout, we center discussion on adaptive responses to threats of disease, accident and assault as common causes of child mortality in the ancestral past.

Placental Corticotropin-Releasing Hormone Mediates the Association Between Prenatal Social Support and Postpartum Depression

Three decades of research point to both biological and psychological risk factors for postpartum depression, but very little research integrates the two. This study bridged this gap by testing whether prenatal social support predicted depressive symptoms at 8 weeks postpartum in a multiethnic sample of 210 women and whether the stress hormone placental corticotropin-releasing hormone (pCRH), measured at 19, 29, and 37 weeks’ gestation, mediated this relationship. We found that prenatal family support predicted significantly fewer depressive symptoms postpartum and more gradual increases in pCRH from 29 to 37 weeks’ gestation. Furthermore, steeper increases in pCRH during this same period predicted more depressive symptoms postpartum. Finally, these changes in pCRH in late pregnancy mediated the relationship between prenatal family support and postpartum depressive symptoms. These results suggest that social and biological risk factors for postpartum depressive symptoms are intertwined and move us closer to an integrated biopsychosocial understanding of postpartum depression.

Racial and Ethnic Differences in Breastfeeding.

OBJECTIVES: Breastfeeding rates differ among racial/ethnic groups in the United States. Our aim was to test whether racial/ethnic disparities in demographic characteristics, hospital use of infant formula, and family history of breastfeeding mediated racial/ethnic gaps in breastfeeding outcomes. METHODS: We analyzed data from the Community and Child Health Network study (N = 1636). Breastfeeding initiation, postnatal intent to breastfeed, and breastfeeding duration were assessed postpartum. Hierarchical linear modeling was used to estimate relative odds of breastfeeding initiation, postnatal intent, and duration among racial/ethnic groups and to test the candidate mediators of maternal age, income, household composition, employment, marital status, postpartum depression, preterm birth, smoking, belief that “breast is best,” family history of breastfeeding, in-hospital formula introduction, and WIC participation. RESULTS: Spanish-speaking Hispanic mothers were most likely to initiate (91%), intend (92%), and maintain (mean duration, 17.1 weeks) breastfeeding, followed by English-speaking Hispanic mothers (initiation 90%, intent 88%; mean duration, 10.4 weeks) and white mothers (initiation 78%, intent 77%; mean duration, 16.5 weeks); black mothers were least likely to initiate (61%), intend (57%), and maintain breastfeeding (mean duration, 6.4 weeks). Demographic variables fully mediated disparities between black and white mothers in intent and initiation, whereas demographic characteristics and in-hospital formula feeding fully mediated breastfeeding duration. Family breastfeeding history and demographic characteristics helped explain the higher breastfeeding rates of Hispanic mothers relative to white and black mothers. CONCLUSIONS: Hospitals and policy makers should limit in-hospital formula feeding and consider family history of breastfeeding and demographic characteristics to reduce racial/ethnic breastfeeding disparities.

Is Postpartum Depression a Disease of Modern Civilization

Access to calorie-dense foods, medicine, and other comforts has made modern humans healthier than our prehistoric ancestors in many respects. However, the epidemics of obesity, diabetes, and cardiovascular disease suggest that there are also drawbacks to modern living. Here, we address the question of whether the dramatic cultural changes that have occurred over the past century have inflated rates of postpartum depression, adding postpartum depression to the list of “diseases of modern civilization.” We review evidence from cross-cultural, epidemiological, and experimental studies documenting associations between postpartum depression and modern patterns of early weaning, diets deficient in essential fatty acids, low levels of physical activity, low levels of sun exposure, and isolation from kin support networks, all of which mark significant divergences from lifestyles believed to have been typical throughout human evolutionary history. This “mismatch hypothesis” of postpartum depression integrates research across diverse research areas and generates novel predictions.

Cortisol in human milk predicts child BMI.

Breastfeeding has been linked to lower rates of childhood obesity. Human milk contains cortisol, known to regulate glucose storage and metabolism. The aim of this study was to to test the hypothesis that early exposure to cortisol in human breast milk helps to modulate infant body mass index (BMI) trajectories over the first 2 years of life.

Response to “Cortisol in Human Milk: The Good, the Bad, or the Ugly?”

TO THE EDITOR: We are thankful for the interest with which Finken and colleagues read our paper and appreciate the opportunity to discuss the important ideas they present. Finken et al. express concern that we assessed milk cortisol at one time point to predict changes in infant BMI percentile (BMIP) because cortisol concentrations in milk vary across the day, reaching their apex shortly after waking and their nadir at night (1,2). While we agree that collecting 24-hour milk samples will constitute an important methodological advance in future research, we consider our current findings to be reliable for several reasons. First, we included the time of day of sample collection in our multivariate growth curve models. By statistically adjusting for temporal variation, we isolated the contribution of milk cortisol on infant BMIP. Second, although it is true that the morning apex and nightly nadir of milk cortisol differ by 500% (1), cortisol variation in the time frame relevant to our study (1100-1700) only differs by 30% (1). Consistent with this limited variation, the correlation between time of day and milk cortisol in our study was relatively modest and only marginally significant (b 5 0.27, P 5 0.050). Given these complementary considerations, our study most likely captured betweenmother variation in milk cortisol, as intended, rather than within-mother variation in diurnal milk cortisol. Furthermore, the vast majority of prior research on early glucocorticoid exposure and later obesity risk derives from samples taken at one time point (3).We are thankful for the interest with which Finken and colleagues read our paper and appreciate the opportunity to discuss the important ideas they present. Finken et al. express concern that we assessed milk cortisol at one time-point to predict changes in infant BMIP because cortisol concentrations in milk vary across the day, reaching their apex shortly after waking and their nadir at night.1,2 While we agree that collecting 24-hour milk samples will constitute an important methodological advance in future research, we regard our current findings to be reliable for several reasons. First, we included the time-of-day of sample collection in our multivariate growth curve models. By statistically adjusting for temporal variation, we isolated the contribution of milk cortisol on infant BMIP. Second, although it is true that the morning apex and nightly nadir of milk cortisol differ by ~500%,1 cortisol variation in the timeframe relevant to our study (1100 – 1700) only differs by ~30%.1 Consistent with this limited variation, the correlation between time-of-day and milk cortisol in our study was relatively modest and only marginally significant (β = .27, p = .050). Given these complementary considerations, our study most likely captured between-mother variation in milk cortisol, as intended, rather than within-mother variation in diurnal milk cortisol. Furthermore, the vast majority of prior research on early glucocorticoid exposure and later obesity risk derives from samples taken at one time-point.3

The Dynamics of Stress and Fatigue Across Menopause: Attractors, Coupling, and Resilience

Objective: The objective of this study was to evaluate the regulatory dynamics between stress and fatigue experienced by women during the menopausal transition (MT) and early postmenopause (EPM). Fatigue and perceived stress are commonly experienced by women during the MT and EPM. We sought to discover relationships between these symptoms and to employ these symptoms as possible markers for resilience. Methods: Participants were drawn from the longitudinal Seattle Midlife Womens Health Study. Eligible women completed questionnaires on 60+ occasions (annual health reports and monthly health diaries) (n = 56 women). The total number of observations across the sample was 4,224. STRAW+10 criteria were used to stage women in either in late reproductive, early or late transition, or EPM stage. Change values were generated for fatigue and stress and analyzed with a multilevel structural equation model; slopes indicate how quickly a person returns to homeostasis after a perturbation. Coupling of stress and fatigue was modeled to evaluate resilience, the notion of maintaining stability during change. Results: Eligible women were on average 35 years old (SD = 4.71), well educated, employed, married or partnered, and white. Fit indices suggested the model depicts the relationships of stress and fatigue (&khgr;2(9 df) = 7.638, P = 0.57, correction factor = 4.9244; root mean square error of approximation (RMSEA) 90% CI = 0.000 ⩽ 0.000 ⩽ 0.032; comparative fit index (CFI) = 1.00). A loss in model fit across stages suggests that the four stages differed in their dynamics (&khgr;2&Dgr;(12 df) = 21.181, P = .048). All stages showed fixed-point attractor dynamics: fatigue became less stable over time; stress generally became more stable over time. Coupling relationships of stress on fatigue show evidence for shifts in regulatory relationships with one another across the MT. Conclusions: Results are suggestive of general dysregulation via disruptions to coupling relationships of stress and fatigue across the MT. Findings support a holistic approach to understanding symptoms and supporting women during the MT.