Impact on birth weight of maternal smoking throughout pregnancy mediated by DNA methylation.

BACKGROUND: Cigarette smoking has severe adverse health consequences in adults and in the offspring of mothers who smoke during pregnancy. One of the most widely reported effects of smoking during pregnancy is reduced birth weight which is in turn associated with chronic disease in adulthood. Epigenome-wide association studies have revealed that smokers show a characteristic "smoking methylation pattern", and recent authors have proposed that DNA methylation mediates the impact of maternal smoking on birth weight. The aims of the present study were to replicate previous reports that methylation mediates the effect of maternal smoking on birth weight, and for the first time to investigate whether the observed mediation effects are sex-specific in order to account for known sex-specific differences in methylation levels. METHODS: Methylation levels in the cord blood of 313 newborns were determined using the Illumina HumanMethylation450K Beadchip. A total of 5,527 CpG sites selected on the basis of evidence from the literature were tested. To determine whether the observed association between maternal smoking and birth weight was attributable to methylation, mediation analyses were performed for significant CpG sites. Separate analyses were then performed in males and females. RESULTS: Following quality control, 282 newborns eventually remained in the analysis. A total of 25 mothers had smoked consistently throughout the pregnancy. The birthweigt of newborns whose mothers had smoked throughout pregnancy was reduced by >200g. After correction for multiple testing, 30 CpGs showed differential methylation in the maternal smoking subgroup including top "smoking methylation pattern" genes AHRR, MYO1G, GFI1, CYP1A1, and CNTNAP2. The effect of maternal smoking on birth weight was partly mediated by the methylation of cg25325512 (PIM1); cg25949550 (CNTNAP2); and cg08699196 (ITGB7). Sex-specific analyses revealed a mediating effect for cg25949550 (CNTNAP2) in male newborns. CONCLUSION: The present data replicate previous findings that methylation can mediate the effect of maternal smoking on birth weight. The analysis of sex-dependent mediation effects suggests that the sex of the newborn may have an influence. Larger studies are warranted to investigate the role of both the identified differentially methylated loci and the sex of the newborn in mediating the association between maternal smoking during pregnancy and birth weight.

Impact of prenatal stress on the dyadic behavior of mothers and their 6-month-old infants during a play situation: role of different dimensions of stress.

Prenatal stress (PS) is an established risk factor in the etiology of mental disorders. Although mother-child interaction is the infant's first important training in dealing with stress, little is yet known about the impact of PS on mother-infant dyadic behavior. The current study aimed to elucidate the prospective influence of psychological and physiological stresses during pregnancy on mother-infant dyadic behavior. Mother-infant interactions were videotaped at 6-month postpartum and coded into three dyadic patterns: (1) both positive; (2) infant protesting-mother positive; and (3) infant protesting-mother negative, using the infant and caregiver engagement phases. Exposure to PS was assessed during pregnancy using psychological (i.e., psychopathological, perceived, and psychosocial PS; n = 164) and physiological stress measures (i.e., maternal cortisol; n = 134). Group comparisons showed that psychosocial PS was predictive of mother-infant behavior at 6-month postpartum, indicating that dyads of prenatally high-stressed mothers exhibited significantly more positive interaction patterns (i.e., infant positive-mother positive) as compared to the prenatally low-stressed group. Physiological PS was unrelated to mother-infant behavior. These results suggest that mild psychosocial PS may be advantageous for positive mother-infant dyadic behavior, which is in accordance with the stress-inoculation model that assumes a beneficial effect of PS.

Nightmare frequency in last trimester of pregnancy.

BACKGROUND: Pregnancy-related dreams are often found in pregnant women but also the number of negatively toned dreams seems to be increased in this challenging phase of a woman's life. METHODS: Nightmare frequency and subjectively experienced stress was elicited via questionnaires. The mothers-to-be were approached during their application visit about 4-8 weeks prior to delivery in three obstetric hospitals. The present analysis included 406 women aged 16-40 years in the last trimester of their pregnancy. Women with severe somatic illnesses and/or psychiatric disorders were excluded. The representative sample included 496 women (age range: 14-93 years.). RESULTS: The findings clearly indicate that pregnant women report nightmares more often compared to a representative sample and that nightmare frequency is closely related to subjectively experienced stress during daytime. Moreover, baby-related dreams were correlated with nightmare frequency but not with day-time stress. CONCLUSIONS: Future studies should investigate the prevalence of nightmare disorders in pregnancy and study whether brief interventions like Imagery Rehearsal Therapy are beneficial for pregnant women suffering from nightmares.

Urbanicity, behavior problems and HPA axis regulation in preschoolers.

Growing up in cities is associated with increased risk for developing mental health problems. Stress exposure and altered stress regulation have been proposed as mechanisms linking urbanicity and psychopathology, with most research conducted in adult populations. Here, we focus on early childhood, and investigate urbanicity, behavior problems and the regulation of the hypothalamus-pituitary-adrenal (HPA) axis, a central circuit of the stress system, in a sample of N = 399 preschoolers aged 45 months. Urbanicity was coded dichotomously distinguishing between residences with more or less than 100,000 inhabitants. Behavior problems were measured using the Child Behavior Checklist (CBCL) 1½ - 5. Cortisol stress reactivity was assessed using an age-appropriated game-like stress task, and cortisol in the first morning urine was measured to assess nocturnal HPA axis activity. Urbanicity was not associated with behavior problems, urinary cortisol or the cortisol stress response. Neither urinary cortisol nor salivary cortisol response after stress exposure were identified as mediators of the relationship between urbanicity and behavior problems. The findings suggest no strong association of urbanicity with behavior problems and HPA axis regulation in preschool age. To our knowledge, this is the youngest sample to date studying the relationship between urbanicity and behavior problems as well as HPA axis regulation. Future research should examine at which age associations can first be identified and which mechanisms contribute to these relationships.

Nightmares and Stress: A Longitudinal Study.

STUDY OBJECTIVES: In nightmare etiology, trait and state factors play important roles. However, the interaction of state and trait factors has never been studied in a longitudinal design. METHODS: The current sample included 406 pregnant women who were followed up approximately 6 months after giving birth (n = 375) and 4 years later (n = 302). A nightmare frequency scale and several stress-related questionnaires were presented at three measurement points. RESULTS: Despite the major life events in this sample, nightmare frequency was very stable over this time period and decreased slightly. In line with previous findings, cross-sectional analyses showed that stressors were associated with current nightmare frequency but longitudinal analyses indicated that previously measured nightmare frequency showed even stronger effects on current nightmare frequency. CONCLUSIONS: Because the nightmare frequencies were very stable, it would be desirable to carry out intervention studies treating nightmares as early as possible-even in childhood-and study whether nightmare occurrence is lower even years after the intervention. CITATION: Schredl M, Gilles M, Wolf I, Peus V, Scharnholz B, Sütterlin M, Bardtke S, Send TS, Samaras A, Deuschle M. Nightmares and stress: a longitudinal study. J Clin Sleep Med. 2019;15(9):1209-1215.

Maternal hypothalamus-pituitary-adrenal (HPA) system activity and stress during pregnancy: Effects on gestational age and infant's anthropometric measures at birth.

BACKGROUND: Prenatal maternal stress might be a risk for the developing fetus and may have long-lasting effects on child and adult vulnerability to somatic and psychiatric disease. Over-exposure of the unborn to excess glucocorticoids and subsequent alteration of fetal development is hypothesized to be one of the key mechanisms linking prenatal stress with negative child outcome. METHODS: In this prospective longitudinal study, mothers-to-be (n = 405) in late pregnancy (36.8 ±â€¯1.9 weeks of gestational age) and their singleton neonates were studied. We investigated the impact of different prenatal stress indices derived from six stress variables (perceived stress, specific prenatal worries, negative life events, symptoms of depression, trait anxiety, neuroticism) and diurnal maternal saliva cortisol secretion on gestational age and anthropometric measures at birth. RESULTS: Maternal prenatal distress during late gestation was associated with significant reduction in birth weight (-217 g; p = .005), birth length (-1.2 cm; p = .005) and head circumference (-0.8 cm; p = .001). Prenatal stress was modestly but significantly associated with altered diurnal cortisol pattern (flattened cortisol decline and higher evening cortisol), which in turn was significantly related to reduced length of gestation. No evidence for a profound interaction between maternal cortisol level in late pregnancy and infant's anthropometric measures at birth (i.e., birth weight, length, head circumference) was found. CONCLUSION: Prenatal stress is associated with flattened circadian saliva cortisol profiles and reduced infant's anthropometric measures at birth. HPA system activity during pregnancy may be related to low gestational age. The effect of prenatal stress might be partly mediated by maternal-placental-fetal neuroendocrine mechanisms especially the dysregulation of diurnal cortisol profile.

Impact of prenatal stress on mother-infant dyadic behavior during the still-face paradigm.

BACKGROUND: Mother-infant interaction provides important training for the infant's ability to cope with stress and the development of resilience. Prenatal stress (PS) and its impact on the offspring's development have long been a focus of stress research, with studies highlighting both harmful and beneficial effects. The aim of the current study was to examine the possible influence of both psychological stress and hypothalamic-pituitary-adrenal (HPA) axis activity during pregnancy with mother-child dyadic behavior following stress exposure. METHODS: The behavior of 164 mother-infant dyads during the still-face situation was filmed at six months postpartum and coded into three dyadic patterns: 1) both positive, 2) infant protesting-mother positive, and 3) infant protesting-mother negative. PS exposure was assessed prenatally according to psychological measures (i.e., psychopathological, perceived and psychosocial PS; n = 164) and HPA axis activity measures (maternal salivary cortisol, i.e., cortisol decline and area under the curve with respect to ground (AUCg); n = 134). RESULTS: Mother-infant dyads in both the high- and low-stress groups showed decreasing positive and increasing negative dyadic behavior in the reunion episode, which is associated with the well-known "still-face" and "carry-over" effect. Furthermore, mother-infant dyads with higher psychosocial PS exhibited significantly more positive dyadic behavior than the low psychosocial PS group in the first play episode, but not in the reunion episode. Similarly, mother-infant dyads with high HPA axis activity (i.e. high AUCg) but steeper diurnal cortisol decline (i.e. cortisol decline) displayed significantly less negative behavior in the reunion episode than dyads with low HPA axis activity. No significant results were found for psychopathological stress and perceived stress. CONCLUSIONS: The results suggest a beneficial effect of higher psychosocial PS and higher prenatal maternal HPA axis activity in late gestation, which is in line with "stress inoculation" theories.

Telomere Length in Newborns is Related to Maternal Stress During Pregnancy.

Telomere length (TL) is a marker of biological aging, and numerous studies have shown associations between TL and somatic or psychiatric disorders. Research also indicates an association between maternal stress during pregnancy and TL in the offspring. The present study investigated possible associations between TL and: (1) maternal perceived stress during pregnancy; (2) a maternal lifetime history of psychiatric disorder (lifetime PD); and (3) paternal age. TL was analyzed in 319 newborns and 318 mothers from a predominantly Caucasian sample (n=273 Caucasian newborns and n=274 Caucasian mothers). Two key findings were observed. First, maternal perceived stress during pregnancy was associated with shorter telomeres in newborns but not with maternal TL. Second, maternal lifetime PD was associated with shorter maternal telomeres, but not with TL in newborns. Paternal age was not associated with TL in newborns. The finding that maternal stress during pregnancy is associated with shorter telomeres in newborns supports the results of smaller previous studies. The fact that a relation between maternal prenatal stress and TL was observed in the offspring but not in mothers may be attributable to a high vulnerability to stress during intrauterine development of a maturing organism. To our knowledge, this is the largest study to date to show that maternal stress during pregnancy but not maternal lifetime PD is associated with shorter telomeres in the offspring.

New-born females show higher stress- and genotype-independent methylation of SLC6A4 than males.

BACKGROUND: Research has demonstrated an association between exposure to early life stress and an increased risk of psychiatric disorders in later life, in particular depression. However, the mechanism through which early life stress contributes to disease development remains unclear. Previous studies have reported an association between early life stress and altered methylation of the serotonin transporter gene (SLC6A4), a key candidate gene for several psychiatric disorders. These differences in methylation are influenced by sex and genetic variation in the SLC6A4-linked polymorphic region (5-HTTLPR). Furthermore, one study indicated that stress during pregnancy may induce methylation changes in SLC6A4 in the newborn. The present study is the first to investigate whether early life stress during pregnancy impacts on SLC6A4 methylation in newborns, taking into account the influence of genetic variation and sex. METHODS: Cord blood was obtained from newborns with high (n = 45) or low (n = 45) early life stress, defined as maternal stress during pregnancy. The effect on methylation of early life stress, 5-HTTLPR genotype, and sex was assessed at four cytosin-phosphate-guanine dinucleotide (CpG) sites in the promoter associated CpG island north shore (CpG 1 to 4). The epigenetic analyses focused on these CpG sites, since research has shown that CpG island shore methylation has functional consequences. RESULTS: Significant sex-specific methylation was observed, with females displaying higher methylation levels than males (p < 0.001). Importantly, this effect was influenced by neither early life stress nor genotype. CONCLUSIONS: The present data suggest that sex-specific methylation of SLC6A4 is present at birth, and is independent of early life stress and 5-HTTLPR genotype. This may contribute to the sex-specific prevalence of depression.