***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND The goal of our study was to measure the effectiveness of a home-based intervention for prevention of low birth weight with 154 high-risk , low-income black women attending a prenatal clinic in Clevel and . METHODS Based on previous research , risk was defined by clinic registration between the 17th and 28th weeks of gestation , low family functioning score , and experience of at least one stressful life event prior to registration . Optional factors included being a smoker , a low maternal weight-height ratio , being age 27 or older , and a previous premature birth . A 21-item family function screen previously vali date d in a similar population was the primary determinant of psychosocial risk . Low birth weight was defined as weight less than 2,500 g regardless of gestational age . RESULTS There was no decrease in the rate of low birth weight for women who received four home visits focusing on smoking , drug and nutrition education , support , and links with community services , compared to women who received no visits . The number of prenatal visits was significantly higher in the intervention group , but an increased number of prenatal visits did not correlate with a reduced rate of low birth weight . Despite previous research , the family function screen was not an effective predictor of low birth weight in our study . A revised equation involving a history of previous premature birth , smoking , and a low maternal weight-height ratio did predict low birth weight . CONCLUSIONS These findings question the utility of short-term psychosocial interventions for influencing low birth-weight rates in low-income black clinic population s. The family function screen was not cross vali date d. Integration of any psychosocial intervention with the routine prenatal care occurring in the obstetrical clinic is suggested for future research The authors investigated a large number of stressors and measures of psychological distress in a multicenter , prospect i ve cohort study of spontaneous preterm birth among 5,337 Montreal (Canada)-area women who delivered from October 1999 to April 2004 . In addition , a nested case-control analysis ( 207 cases , 444 controls ) was used to explore potential biologic pathways by analyzing maternal plasma corticotrophin-releasing hormone ( CRH ) , placental histopathology , and ( in a subset ) maternal hair cortisol . Among the large number of stress and distress measures studied , only pregnancy-related anxiety was consistently and independently associated with spontaneous preterm birth ( for values above the median , adjusted odds ratio = 1.8 ( 95 % confidence interval : 1.3 , 2.4 ) ) , with a dose-response relation across quartiles . The maternal plasma CRH concentration was significantly higher in cases than in controls in crude analyses but not after adjustment ( for concentrations above the median , adjusted odds ratio = 1.1 ( 95 % confidence interval : 0.8 , 1.6 ) ) . In the subgroup ( n = 117 ) of participants with a sufficient maternal hair sample , hair cortisol was positively associated with gestational age . Neither maternal plasma CRH , hair cortisol , nor placental histopathologic features of infection/inflammation , infa rct ion , or maternal vasculopathy were significantly associated with pregnancy-related anxiety or any other stress or distress measure . The biologic pathways underlying stress-induced preterm birth remain poorly understood This study investigates the relationship between adverse pregnancy outcomes in high-risk African American women in Washington , DC and sociodemographic risk factors , behavioral risk factors , and the most common and interrelated medical conditions occurring during pregnancy : diabetes , hypertension , preeclampsia , and Body Mass Index ( BMI ) . Data are from a r and omized controlled trial conducted in 6 prenatal clinics . Women in their 1st or 2nd trimester were screened for behavioral risks ( smoking , environmental tobacco smoke exposure , depression , and intimate partner violence ) and demographic eligibility . 1,044 were eligible , interviewed and followed through their pregnancies . Classification and Regression Trees ( CART ) methodology was used to : ( 1 ) explore the relationship between medical and behavioral risks ( reported at enrollment ) , sociodemographic factors and pregnancy outcomes ; ( 2 ) identify the relative importance of various predictors of adverse pregnancy outcomes ; and ( 3 ) characterize women at the highest risk of poor pregnancy outcomes . The strongest predictors of poor outcomes were prepregnancy BMI , preconceptional diabetes , employment status , intimate partner violence , and depression . In CART analysis , preeclampsia was the first splitter for low birthweight ; preconceptional diabetes was the first splitter for preterm birth ( PTB ) and neonatal intensive care admission ; BMI was the first splitter for very PTB , large for gestational age , Cesarean section and perinatal death ; employment was the first splitter for miscarriage . Preconceptional factors strongly influence pregnancy outcomes . For many of these women , the high risks they brought into pregnancy were more likely to impact their pregnancy outcomes than events during pregnancy Prenatal psychosocial predictors of infant birth weight and length of gestation were investigated in a prospect i ve study of 120 Hispanic and 110 White pregnant women . Hypotheses specifying that personal re sources ( mastery , self-esteem , optimism )  ,  prenatal stress ( state and pregnancy anxiety ) , and sociocultural factors ( income , education , ethnicity ) would have different effects on birth outcomes were tested using structural equation modeling . Results confirmed that women with stronger re sources had higher birth weight babies ( beta = .21 ) , whereas those reporting more stress had shorter gestations ( beta = -.20 ) . Re sources were also associated with lower stress ( beta = -.67 ) , being married , being White , having higher income and education , and giving birth for the first time . There was no evidence that re sources buffered the effects of stress . The importance of personal re sources in pregnancy is highlighted along with implication s for underst and ing the etiology of adverse birth outcomes Background : The aim of our study was to evaluate how sociodemographic factors , psychosocial adaptation to pregnancy and well-being levels are associated with the onset of preterm uterine contractions allowing symptomatic preterm labor . Methods : In a prospect i ve case-control design , 51 consecutive women admitted for threatened preterm labor were enrolled . The patients received st and ard care . The day before discharge , once contractions had been stopped , the patients were administered 2 question naires : the Prenatal Self-Evaluation Question naire of Lederman and the Psychological Well-Being Scales .  Controls were enrolled among asymptomatic , healthy women attending routine prenatal care .  They were matched for parity and gestational age . Results : Gestational age at inclusion ranged from 25 to 34 weeks . Fourteen cases and 4 controls delivered preterm . Cases were less educated than controls , showed a lower acceptance of pregnancy and worse relationship with others , namely with the husb and , compared to controls . They also displayed a reduced environmental mastery . Conclusion : Having a low education , poor relationship with others , including the husb and , and impaired coping skills appeared to be independent risk factors for the development of symptomatic preterm labor in urbanized women OBJECTIVE Selective serotonin reuptake inhibitor ( SSRI ) use during pregnancy incurs a low absolute risk for major malformations ; however , other adverse outcomes have been reported . Major depression also affects reproductive outcomes . This study examined whether 1 ) minor physical anomalies , 2 ) maternal weight gain and infant birth weight , 3 ) preterm birth , and 4 ) neonatal adaptation are affected by SSRI or depression exposure . METHOD This prospect i ve observational investigation included maternal assessment s at 20 , 30 , and 36 weeks of gestation . Neonatal outcomes were obtained by blinded review of delivery records and infant examinations . Pregnant women ( N=238 ) were categorized into three mutually exclusive exposure groups : 1 ) no SSRI , no depression ( N=131 ) ; 2 ) SSRI exposure ( N=71 ) , either continuous ( N=48 ) or partial ( N=23 ) ; and 3 ) major depressive disorder ( N=36 ) , either continuous ( N=14 ) or partial ( N=22 ) . The mean depressive symptom level of the group with continuous depression and no SSRI exposure was significantly greater than for all other groups , demonstrating the expected treatment effect of SSRIs . Main outcomes were minor physical anomalies , maternal weight gain , infant birth weight , pregnancy duration , and neonatal characteristics . RESULTS Infants exposed to either SSRIs or depression continuously across gestation were more likely to be born preterm than infants with partial or no exposure . Neither SSRI nor depression exposure increased risk for minor physical anomalies or reduced maternal weight gain . Mean infant birth weights were equivalent . Other neonatal outcomes were similar , except 5-minute Apgar scores . CONCLUSIONS For depressed pregnant women , both continuous SSRI exposure and continuous untreated depression were associated with preterm birth rates exceeding 20 % BACKGROUND The impact of prenatal depression on pregnancy outcomes is largely unknown . METHODS We conducted a population -based prospect i ve cohort study among pregnant women of the Kaiser Permanente Medical Care Program to examine the impact of prenatal depression on the risk of preterm delivery . We interviewed pregnant women in their early pregnancy . Women 's depressive symptoms were ascertained using the st and ard Center for Epidemiological Studies Depression Scale ( CESD ) . The presence of significant prenatal depressive symptoms and severe depressive symptoms was determined by CESD scores > or = 16 and > or = 22 , respectively . RESULTS Among the 791 participants who answered CESD questions and delivered a live birth , after controlling for potential confounders using the Cox proportional hazard regression , women with CESD scores > or = 16 had almost twice the risk of preterm delivery compared with women without depressive symptoms : adjusted hazard ratio ( aHR ) = 1.9 , 95 % confidence interval ( CI ) 1.0 - 3.7 . The risk of preterm delivery increased with increasing severity of depression : aHR = 1.6 ( CI 0.7 - 3.6 ) for CESD 16 - 21 and aHR = 2.2 ( CI 1.1 - 4.7 ) for CESD > or = 22 . The risk of preterm delivery associated with prenatal depression appears to be exacerbated by low educational level , a history of fertility problems and the presence of obesity and stressful events . The observed associations were not confounded by the use of antidepressants , although some of the associations did not reach statistical significance . CONCLUSIONS Our findings show that pregnant women with depressive symptoms are at increased risk of preterm delivery and , in addition , provide preliminary evidence that social and reproductive risk factors as well as obesity and stressful events may exacerbate the effect Objective : The high rate of preterm births is an imposing public health issue in the United States . Past research has suggested that prenatal stress , anxiety , and elevated levels of maternal plasma corticotropin-releasing hormone ( CRH ) are associated with preterm delivery in humans and animals . Studies to date have not examined all three variables together ; that is the objective of this paper . Methods : Data from 282 pregnant women were analyzed to investigate the effect of maternal prenatal anxiety and CRH on the length of gestation . It was hypothesized that at both 18 to 20 weeks ( Time 1 ) and 28 to 30 weeks gestation ( Time 2 ) , CRH and maternal prenatal anxiety would be negatively associated with gestational age at delivery .  CRH was also expected to mediate the relationship between maternal prenatal anxiety and gestational age at delivery . Results : Findings supported the mediation hypothesis at Time 2 , indicating that women with high CRH levels and high maternal prenatal anxiety at 28 to 30 weeks gestation delivered earlier than women with lower CRH levels and maternal prenatal anxiety . Women who delivered preterm had significantly higher rates of CRH at both 18 to 20 weeks gestation and 28 to 30 weeks gestation ( p < .001 ) compared with women who delivered term . Conclusions : These findings are the first to link both psychosocial and neuroendocrine factors to birth outcomes in a prospect i ve design . ANOVA = analysis of variance ; BIPS = Behavior in Pregnancy Study ; CRH = corticotropin-releasing hormone ; HPA = hypothalamic-pituitary-adrenal axis ; SNS = sympathetic nervous system OBJECTIVE The aim was to test a model of the influence of maternal prenatal psychosocial stress on birth outcomes after controlling for biomedical risk . STUDY DESIGN In a prospect i ve study a sociodemographically homogeneous sample of 90 women was assessed during the third trimester with st and ard , reliable question naires that measured episodic and chronic stress , strain  ( response to stress ) , and pregnancy-related anxiety . Birth outcomes included infant birth weight , gestational age at birth , and intrapartum complications . Parity and biomedical ( antepartum ) risk was also coded . Bivariate and multivariate analyses were performed after controlling for the effects of biomedical risk factors . RESULTS Independent of biomedical risk , each unit increase of prenatal life event stress ( from a possible sample range of 14.7 units ) was associated with a 55.03 gm decrease in infant birth weight and with a significant increase in the likelihood of low birth weight ( odds ratio 1.32 ) , and each unit increase of prenatal pregnancy anxiety ( from a possible sample range of 5 units ) was associated with a 3-day decrease in gestational age at birth . CONCLUSION Independent of biomedical risk , maternal prenatal stress factors are significantly associated with infant birth weight and with gestational age at birth Objectives : This study examined associations between  reported pregnancy 
    Output:
    
There is strong evidence that antenatal distress during the pregnancy increases the likelihood of preterm birth .
CONCLUSION Complex paths of significant interactions between depression , anxiety and stress , risk factors and preterm birth were indicated in both direct and indirect ways .
The effects of pregnancy distress were associated with spontaneous but not with medically indicated preterm birth .