Thomas G. O’Connor

Prenatal anxiety predicts individual differences in cortisol in pre-adolescent children

BACKGROUND Animal studies suggest that prenatal stress is associated with long-term disturbance in hypothalamic-pituitary-adrenal (HPA) axis function, but evidence in humans is lacking. This study examined the long-term association between prenatal anxiety and measures of diurnal cortisol at age 10 years. METHODS Measures of cortisol were collected at awakening, 30 min after awakening, and at 4 pm and 9 pm on 3 consecutive days in a sample of 10-year-olds (n = 74) from the Avon Longitudinal Study of Parents and Children, a prospective longitudinal cohort study of mothers and children on whom measures of anxiety and depression were collected in pregnancy and the postpartum period. Analyses examined the links between symptoms of prenatal anxiety and multiple indicators of cortisol, an index of HPA axis functioning. RESULTS Prenatal anxiety was significantly associated with individual differences in awakening and afternoon cortisol after accounting for obstetric and sociodemographic risk (partial correlations were .32 and .25, p < .05). The effect for awakening cortisol remained significant after controlling for multiple postnatal assessments of maternal anxiety and depression. CONCLUSIONS This study provides the first human evidence that prenatal anxiety might have lasting effects on HPA axis functioning in the child and that prenatal anxiety might constitute a mechanism for an increased vulnerability to psychopathology in children and adolescents.

Prenatal stress and the programming of the HPA axis

There are several independent prospective studies showing that a wide variety of forms of prenatal stress can have long-term effects on the behavioural and cognitive outcome for the child. Animal studies have shown that prenatal stress, as well as affecting behaviour, can also reprogram the function of the HPA axis in the offspring. However, the effects on the HPA axis are very variable depending on the nature of the stress, its timing in gestation, the genetic strain of the animal, the sex and age of the offspring and whether basal or stimulated HPA axis responses are studied. There are also several recent studies showing long-term effects of prenatal stress on basal cortisol levels, or cortisol responses to stress, in humans. The designs of these studies differ considerably, many are small, and the effects on outcome are also varied. There is little evidence, so far, that altered function of the HPA axis in the child mediates the behavioural or cognitive alterations observed to be associated with prenatal stress.

Prenatal Stress and Neurodevelopment of the Child: Focus on the HPA Axis and Role of the Placenta

Recent human studies have shown that a wide variety of prenatal stressors, from anxiety and partner relationship problems, to natural disasters, increase the risk for a diverse range of adverse neurodevelopmental outcomes in the child. These include impaired cognitive development and behavioral problems, autism and schizophrenia. However, many questions remain about the underlying processes. Much of the research, based on animal studies, has focussed on the maternal HPA axis, with mixed results. Maternal stress or anxiety during pregnancy has been found to be weakly associated with raised maternal cortisol, if at all. The placenta may be a more promising programming vector, because it controls fetal exposure to the maternal environment. Animal studies indicate that prenatal stress can affect the activity of the placental barrier enzyme 11-βHSD2, which metabolises cortisol. We review the evidence for a similar mechanism in humans and how maternal stress may cause other changes in the placenta which affect fetal neurodevelopment.

Maternal prenatal anxiety and downregulation of placental 11β-HSD2

BACKGROUND Raised maternal anxiety during pregnancy is associated with increased risk of adverse neurodevelopmental outcomes for her child. The mechanisms underlying this are not known but animal studies suggest prenatal stress may alter the function of the placenta. Here we determined whether maternal prenatal anxiety was associated with a downregulation of placental 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2), the enzyme which metabolises cortisol. METHODS We recruited mothers the day before delivery by elective caesarean, and gave them the Spielberger Trait and State anxiety and Edinburgh Depression self-rating scales. Placentae were collected and aliquots stored for later analysis. RESULTS Prenatal Trait anxiety was negatively correlated with placental 11β-HSD2 mRNA expression (r=-0.40, p<0.01, n=56). Results were similar with male and female fetuses (r=-0.39, p=0.04, n=28; r=-0.40, p=0.03, n=28) respectively. Results were also significant with State anxiety (r=-0.27, p=0.05, n=56) but somewhat weaker for depression (r=-0.20, p=0.13, n=56). Preliminary analyses on a subset of cases (n=25) suggested parallel results for enzyme activity. CONCLUSIONS These findings provide evidence for an association between prenatal maternal mood and downregulation of placental 11β-HSD2. Results are consistent with raised maternal anxiety being associated with increased fetal exposure to maternal cortisol, and support the hypothesis that this may be one mechanism underlying fetal programming by prenatal stress.

Association between maternal and amniotic fluid cortisol is moderated by maternal anxiety

Maternal stress or anxiety during pregnancy can lead to neurodevelopmental and other problems in the child, and cortisol is one possible mediator. Animal models show that maternal prenatal stress can affect placental function, including regulation of placental 11beta-HSD2, the main barrier to the placental passage of cortisol. It is not known whether a parallel process exists in humans. The aim of the current study was to determine whether maternal anxiety increases the association between maternal plasma cortisol and amniotic fluid cortisol. The sample consisted of 262 women having amniocentesis, with normal pregnancies, who completed Spielberger State and Trait anxiety scales, from whom a plasma sample and an aliquot of amniotic fluid was obtained. The correlation between maternal and amniotic fluid cortisol was strongly dependent on both State and Trait maternal anxiety; in the most anxious State quartile r(62)=.59, p<.001 and in the least r(60)=.05, ns, a significant difference (p<.0015). The moderating effect of maternal anxiety on the association between maternal plasma and amniotic fluid cortisol remained when gestational age, maternal age, fetal sex, medication and time of collection were controlled for. There was no difference in amniotic fluid cortisol levels between the most and least anxious groups of mothers. However, the finding that there is a stronger correlation between maternal and fetal cortisol among more anxious pregnant women does suggests that the maternal emotional state can affect the function of the placenta.

Maternal Antenatal Anxiety and Amniotic Fluid Cortisol and Testosterone: Possible Implications for Foetal Programming

Both animal and human studies have shown that maternal stress or anxiety during pregnancy is associated with increased risk of disturbance in offspring neurodevelopment and behaviour. In animal models, increased foetal exposure to glucocorticoids has been found to be one mechanism for such foetal programming. Little is understood of the mediating mechanisms in humans, and one aim of our research programme is to investigate this further. This review presents a synopsis of some of our recent results. We aimed to test the hypothesis that maternal anxiety was associated with raised maternal cortisol, and that this in turn was related to increased foetal exposure to cortisol. We studied this by recruiting women at amniocentesis, obtained their Spielberger State Anxiety scores, and assessed maternal plasma cortisol and amniotic fluid cortisol. We also examined maternal plasma and amniotic fluid testosterone levels. Awaiting amniocentesis was in general anxiogenic, but with a wide range of anxiety scores. Maternal anxiety was significantly associated with plasma cortisol before 17 weeks, albeit of modest magnitude (r = 0.0.23), and not after 17 weeks of gestation. This is probably due to the known attenuation of the maternal hypothalamic‐pituitary‐adrenal axis with increasing gestation. We found a strong correlation between maternal plasma and amniotic fluid cortisol levels, which increased with gestation and became robust after 18 weeks. This correlation increased with maternal anxiety, suggesting a possible effect of maternal mood on placental function. There was a positive correlation between cortisol and testosterone in amniotic fluid, in both male and female foetuses independent of maternal anxiety, plasma testosterone, gestational age, and time of collection. Foetal stress may be associated with increased foetal exposure to testosterone. However, maternal anxiety did not predict amniotic fluid cortisol or testosterone level. Thus, the role of these hormones in mediating the effect of maternal mood on foetal development in humans remains to be demonstrated.

Prenatal maternal mood is associated with altered diurnal cortisol in adolescence

BACKGROUND Experimental animal work shows that prenatal stress has a persisting effect on the hypothalamic-pituitary-adrenal (HPA) axis of offspring. The implications of these findings for human health and development are not yet clear. METHODS The data are based on the ALSPAC cohort, a prospective longitudinal study of a community sample that has followed mothers and children from pregnancy. When the children were aged 15 years, diurnal cortisol samples were collected at wake-up, 30 min post-awakening and at afternoon and evening times on up to three consecutive days on n=889 adolescents. Diurnal cortisol was predicted from prenatal anxiety and depression, obstetric, life-style, socio-demographic, and postnatal covariates. RESULTS Multilevel model analysis indicated that maternal prenatal anxiety was associated with a modest alteration of diurnal cortisol, indexed by a reduced cortisol awakening response and flatter diurnal slope. The effects were independent of psychosocial and obstetric covariates and measures of maternal postnatal anxiety; effects were similar for prenatal maternal depression. There was no association between adolescent cortisol and paternal prenatal anxiety. CONCLUSIONS There are small but persisting associations between maternal prenatal mood and diurnal cortisol in the child that persist into adolescence and may constitute a programming effect.

Quality of child-parent attachment moderates the impact of antenatal stress on child fearfulness.

BACKGROUND Animal studies have shown that prenatal stress has persisting effects on several aspects of offspring development; more recent studies show that this effect may be eliminated by positive postnatal rearing. Human studies of prenatal anxiety/stress are now also beginning to document links between antenatal stress/anxiety and behavioural and cognitive development of the child; however, there is no human evidence as to whether the early caregiving environment moderates the effect of antenatal anxiety/stress on child outcomes. METHODS Antenatal and postnatal measures of stress were collected on 123 women who were recruited from an antenatal clinic. Laboratory-based assessment of the childrens cognitive development and fearfulness were assessed when the children were aged 17 months. In addition, child-parent attachment quality was assessed using the Strange Situation. RESULTS Attachment classification moderated the link between antenatal stress and observed fearfulness. The effect of antenatal stress on fearfulness was most accentuated in children with an Insecure/Resistant attachment classification; the significant antenatal stress x attachment classification interaction held after controlling for postnatal stress and obstetric, social and demographic factors. Attachment did not moderate the effects of antenatal anxiety on cognitive development. DISCUSSION These findings provide the first human evidence that postnatal parenting may moderate the adverse effects of antenatal stress. These results raise developmental questions about the timing and effect of interventions to reduce the adverse effects of antenatal stress exposure.

The associations between psychosocial stress and the frequency of illness, and innate and adaptive immune function in children

OBJECTIVE Family processes have a substantial impact on childrens social and emotional well-being, but little is known about the effects of family stress on childrens physical health. To begin to identify potential links between family stress and health in children, we examined associations between specific aspects of family psychosocial stress and the frequency of illnesses in children, measures of innate and adaptive immune function, and human herpesvirus 6 (HHV-6) reactivation. STUDY DESIGN Prospective study of 169 ambulatory school-age children and parents. Parents completed multiple assessments of stress at 7 sequential six-month visits and maintained weekly illness diaries for their children over three years using a thermometer to record fever. Children had blood obtained for HHV-6 and immune function studies at each visit including natural killer (NK) cell function and the percentage of CD4 and CD8 cells associated with immune control of cytomegalovirus (CMV). RESULTS Parental psychiatric symptoms were associated with a higher frequency of illnesses: for each 1 U increase in symptom score children had an increased 1-year rate of total illnesses of 40% (rate ratio, 1.40; 95% CI, 1.06-1.85) and febrile illnesses of 77% (rate ratio, 1.77, 95% CI, 1.00-3.13). Parental psychiatric symptom scores were also associated with enhanced NK cell function (estimate, 0.15; 95% CI, 0.05-0.26) and increased percentages of CD8+CD28-CD57+ cells in the blood of CMV seropositive children (estimate, 2.57; 95% CI, 0.36-4.79). HHV-6 reactivation was not detected. CONCLUSIONS There is an association between specific psychosocial stress exposure and rates of illness and immune function in normally developing children.

Prenatal Maternal Anxiety Predicts Reduced Adaptive Immunity in Infants

Prenatal anxiety has been linked with altered immune function in offspring in animal studies, but the relevance for human health is unknown. We examined prenatal maternal anxiety as a predictor of adaptive immunity in infants at 2 and 6 months of age as part of a prospective longitudinal study. The humoral immune response to hepatitis B vaccine was assessed at 2 months (n=80) and 6 months (n=76) of age. Prenatal anxiety predicted lower hepatitis B antibody titers at 6 months of age independent of obstetric and socio-demographic covariates; the effects were limited to those infants who had not completed the 3-dose vaccine series (for transformed titer values, r=-.36, p<.05). Cell-mediated immune responses at 2 (n=56) and 6 (n=54) months of age were examined by ELISpot assays for interferon(IFN)-γ, interleukin(IL)-2, and IL-4 responder cell frequencies to three antigens: hepatitis B surface antigen, tetanus toxoid, and phytohaemagglutinin (PHA). Prenatal maternal anxiety was associated with reduced IFN-γ and increased IL-4 responder cell frequencies at 6 months of age, independent of obstetric and socio-demographic covariates. No effect of prenatal anxiety was found on adaptive immunity at 2 months of age. The findings provide the first demonstration in humans that prenatal anxiety alters adaptive immunity in the infant.