***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: OBJECTIVE Our purpose was to determine whether smoking before pregnancy reduces the risk of gestational hypertension or preeclampsia . STUDY DESIGN The trial of Calcium for Preeclampsia Prevention ( CPEP ) was a r and omized study of 4589 nulliparous women conducted in 5 US medical centers during the years 1992 through 1995 . Women were classified into 4 exposure groups by smoking history obtained at study enrollment ( 13 - 21 weeks ' gestation ) : ( 1 ) never smoked , ( 2 ) smoked but quit before the last menstrual period ( LMP ) , ( 3 ) smoked but quit after LMP but before enrollment , and ( 4 ) smoked and still smoking at enrollment . RESULTS After adjustments were made for maternal age , race , body mass index , type of health insurance , and clinical center , women smoking at enrollment had a reduced risk of hypertension ( relative risk = 0.8 ; 95 % CI , 0.6 - 0.9 ) . Women who quit smoking before the LMP did not have reduced risk ( relative risk = 1.1 ; 95 % CI , 0.9 - 1.3 ) . Results were similar for gestational hypertension and preeclampsia examined separately . CONCLUSION Women who smoke but quit before becoming pregnant do not have a reduced risk for gestational hypertension or preeclampsia Abstract Objective To compare the hazards of cigarette smoking in men who formed their habits at different periods , and the extent of the reduction in risk when cigarette smoking is stopped at different ages . Design Prospect i ve study that has continued from 1951 to 2001 . Setting United Kingdom . Participants 34 439 male British doctors . Information about their smoking habits was obtained in 1951 , and periodically thereafter ; cause specific mortality was monitored for 50 years . Main outcome measures Overall mortality by smoking habit , considering separately men born in different periods . Results The excess mortality associated with smoking chiefly involved vascular , neoplastic , and respiratory diseases that can be caused by smoking . Men born in 1900 - 1930 who smoked only cigarettes and continued smoking died on average about 10 years younger than lifelong non-smokers . Cessation at age 60 , 50 , 40 , or 30 years gained , respectively , about 3 , 6 , 9 , or 10 years of life expectancy . The excess mortality associated with cigarette smoking was less for men born in the 19th century and was greatest for men born in the 1920s . The cigarette smoker versus non-smoker probabilities of dying in middle age ( 35 - 69 ) were 42 % ν24 % ( a twofold death rate ratio ) for those born in 1900 - 1909 , but were 43 % ν 15 % ( a threefold death rate ratio ) for those born in the 1920s . At older ages , the cigarette smoker versus non-smoker probabilities of surviving from age 70 to 90 were 10 % ν 12 % at the death rates of the 1950s ( that is , among men born around the 1870s ) but were 7 % ν 33 % ( again a threefold death rate ratio ) at the death rates of the 1990s ( that is , among men born around the 1910s ) . Conclusion A substantial progressive decrease in the mortality rates among non-smokers over the past half century ( due to prevention and improved treatment of disease ) has been wholly outweighed , among cigarette smokers , by a progressive increase in the smoker ν non-smoker death rate ratio due to earlier and more intensive use of cigarettes . Among the men born around 1920 , prolonged cigarette smoking from early adult life tripled age specific mortality rates , but cessation at age 50 halved the hazard , and cessation at age 30 avoided almost all of it BACKGROUND It is well established that smoking has detrimental effects on physical health , but its associations with health-related quality of life ( HRQOL ) and a variety of health behaviors have not been widely investigated in the U.S. population . METHODS Data obtained from the Behavioral Risk Factor Surveillance System ( BRFSS ) , an ongoing , state-based , r and om-digit-dialed telephone survey of non-institutionalized persons aged > or = 18 years in the United States , Guam , Puerto Rico , and the Virgin Isl and s , were used in this investigation . The BRFSS monitors the prevalence of key health- and safety-related behaviors and characteristics . In 2001 and 2002 combined , trained interviewers administered HRQOL questions in 23 states and the District of Columbia ( n=82,918 ) . This analysis was conducted in 2004 . RESULTS Overall , an estimated 22.4 % of adults were current smokers , 24.1 % were former smokers , and 53.6 % never smoked . Current smokers had significantly poorer HRQOL than those who had never smoked , and were more likely to drink heavily , to binge drink , and to report depressive and anxiety symptoms . Additionally , current smokers were significantly more likely than those who never smoked to be physically inactive , to report frequent sleep impairment , to report frequent pain , and to eat less than five servings of fruits and vegetables per day . CONCLUSIONS While there are strong positive relationships between smoking and both alcohol consumption and mood disturbance , smoking is also associated with an array of other modifiable risk factors meriting assessment and intervention . In addition to smoking cessation , the increased morbidity and mortality characterizing smokers may potentially be further reduced by improvements in diet , physical activity , and sleep OBJECTIVE We conducted a large clinical trial to evaluate the effect of low-dose aspirin on the frequency of  preeclampsia in nulliparous women . A secondary objective of the trial was to identify those clinical characteristics that might be predictive for the development of preeclampsia . STUDY DESIGN A total of 2947 healthy women with a single fetus were prospect ively followed up from r and omization at 13 to 27 weeks ' gestation to the end of pregnancy . Of these , 1465 women were assigned to low-dose aspirin and 1482 to placebo . Baseline maternal blood pressure and demographic characteristics were examined for the prediction of preeclampsia . RESULTS Preeclampsia developed in 156 women ( 5.3 % ) . Four characteristics predicted the development of preeclampsia : in order of importance , systolic blood pressure at entry , prepregnancy obesity ( weight as a percentage of desirable weight ) , number of previous abortions or miscarriages , and smoking history . Contrary to previous reports , black race was not a risk factor for preeclampsia . Systolic blood pressure was a better predictor of preeclampsia than either diastolic or mean arterial blood pressure . The greater the blood pressure or prepregnancy weight , the greater was the risk for preeclampsia . If the woman had never smoked or had never been previously pregnant , her risk was also higher than average . A multivariate logistic regression equation based on these four factors was able to define a tenth of the population at very high risk and another tenth at very low risk ; the ratio of risk between these two groups was 12:1 . The p value for each of the multivariate coefficients of the risk equation was systolic blood pressure ( p < 0.001 ) , prepregnancy weight ( p < 0.01 ) , smoking history ( p < 0.01 ) , and gravidity ( p < 0.05 ) . There were no statistically significant differences in the predictive values of these risk factors between women receiving low-dose aspirin or placebo . CONCLUSIONS These risk factors should be of value to practitioners counseling women regarding preeclampsia . Moreover , such risk factors should be considered in the design of future studies dealing with preeclampsia Abstract Objectives : To determine the demographic , environmental , and medical factors that influence the relative weights of the newborn infant and the placenta and compare this ratio with other factors known to predispose to adult ill health . Design : Prospect i ve cohort study . Setting : The tertiary referral centre for perinatal care in Perth , Western Australia . Subjects : 2507 pregnant women who delivered a single live infant at term . Main outcome measures : Placental weight , birth weight , and the ratio of placental weight to birth weight . Results : By multiple regression analysis the placental weight to birthweight ratio was significantly and positively associated with gestational age , female sex , Asian parentage , increasing maternal body mass index , increased maternal weight at booking , lower socioeconomic status , maternal anaemia , and increasing number of cigarettes smoked daily . There were no consistent relations between the placental weight to birthweight ratio and measures of newborn size . Conclusions : The ratio of placental weight to birth weight is not an accurate marker of fetal growth . In its role as a predictor of adult disease the ratio may be acting as a surrogate for other factors which are already known to influence health and may act before or after birth . Determining the role that relative growth rates of the fetus and placenta have in predisposing to adult disease requires prospect i ve study to account for the many confounding variables which complicate this hypothesis . Key messages Retrospective analyses have identified an association between a raised placental weight to birthweight ratio and hypertension in adulthood Accurate estimation of gestational age is crucial when interpreting the placental weight to birthweight ratio Environmental factors associated with alterations in the placental weight to birthweight ratio may not exert their effects exclusively in the antenatal period As a marker of fetal growth the potential usefulness of the placental weight to birthweight ratio is diminished because the ratio is influenced by a multiplicity of factors Prospect i ve study is required to clarify the role of intrauterine programming in the genesis of adult Twenty four women with severe pre-eclampsia diagnosed before 34 weeks ' gestation were compared with 48 r and omly selected controls matched for age and parity . Subjects were studied in the puerperium using a question naire , clinical examination , and review of case records . A history of infertility , headaches ( particularly migraine ) , pre-eclampsia in a previous pregnancy , or a raised serum alpha-fetoprotein concentration at the time of screening for neural tube defect in the index pregnancy were all identified as significant risk factors in the pre-eclamptic women . Maternal age , a history of chronic hypertension or renal disease , or excessive maternal weight were not significantly associated with pre-eclampsia . Almost all the infants of pre-eclamptic women showed retarded growth : 18 were below the 10th centile and only one weighed more than the 25th centile . Four babies died . These observations indicate that pre-eclampsia of early onset may differ from the late onset disease not only in its very high perinatal morbidity and mortality but in its distinctive maternal risk factors Case – control studies have shown inverse associations between cigarette smoking and endometrial cancer risk . However , two small prospect i ve cohort studies have not clearly supported an association . Moreover , quantitative measures of smoking have been examined infrequently . Our aim was to study the association between smoking and endometrial cancer risk in a large prospect i ve cohort . We used proportional hazards models to estimate hazard ratios relating cigarette smoking to endometrial cancer risk among 70 591 women aged 40–59 years at recruitment into a r and omised controlled trial of mammography screening for breast cancer . During an average of 10.6 years of follow-up ( 751 833 person – years ) , a total of 403 women were diagnosed with incident endometrial cancer . We found that a reduced endometrial cancer risk was evident only among women who currently smoked 20 cigarettes per day or more ( hazard ratio=0.62 , 95 % CI=0.42–0.92 , P for trend=0.03 ) . There was some suggestion of an inverse association with smoking duration , but this was less clear . The association did not vary with menopausal status , relative body weight , or the use of hormone replacement therapy , but it appeared to be stronger among parous than nulliparous women . The underlying biological mechanisms of this association remain unclear AIMS Circulating levels of C-reactive protein and serum amyloid A protein increase markedly , and albumin levels fall , during the acute-phase response to tissue injury , infection and inflammation . Some acute-phase proteins have been associated with increased risks of coronary heart disease in long-term prospect i ve studies . The aim of the present study was to determine whether circulating concentrations of C-reactive protein , albumin and serum amyloid A protein are correlated with one another , st and ard vascular risk factors , markers of persistent infection , or indicators of socio-economic status . METHODS AND RESULTS We report a cross-sectional study of 704 individuals without a history of coronary heart disease from five general practice s in Bedfordshire , U.K. Plasma levels of  C-reactive protein  and  serum amyloid A protein  were strongly associated with each other ( 2 P<0.00001 ) and inversely related to levels of serum albumin ( 2 P<0.00001 ) . There were highly significant associations of plasma C-reactive protein concentrations with cigarette smoking and obesity ( 2 P<0.00001 for each ) . Serum albumin levels were strongly associated with blood pressure ( 2 P<0.0001 ) and plasma lipids ( 2 P<0.001 ) , and concentrations of serum amyloid A protein were strongly correlated with obesity ( 2 P<0.0001 ) . CONCLUSION Previously reported long-term prospect i ve studies have found an increased risk of coron 
    Output:
    
A protective effect was consistently found in both nulliparas and multiparas , singleton and multifetal pregnancies , and for mild and severe preeclampsia .
Although current literature does not lend clear evidence to support a particular mechanism for the protective effect of smoking , smoking might have effects on angiogenic factors , endothelial function and the immune system which act to lower risk of preeclampsia .