***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 Genital tract infection accounts for approximately 25 - 40 % of all preterm births . We sought to assess the relationship between preterm birth and selected vaginal bacterial taxa associated with preterm birth either directly or through their association with bacterial vaginosis ( BV ) . STUDY DESIGN Vaginal fluid for Gram stain was collected between 17 and 22 weeks ' gestation as part of a r and omized trial of ultrasound-indicated cerclage for preterm birth prevention in women at high risk for recurrent spontaneous preterm birth .  Bacterial deoxyribonucleic acid was extracted from the Gram stain slides and analyzed using quantitative polymerase chain reaction . RESULTS Among the 499 participants , Mycoplasma was positively correlated with increased risk of preterm ( risk ratio [ RR ] , 1.83 ; 95 % confidence interval [ CI ] , 1.52 - 2.22 ) as was Mobiluncus ( RR , 1.36 ; 95 % CI , 1.07 - 1.73 ) and Atopobium ( RR , 1.44 ; 95 % CI , 1.1 - 1.87 ) . However , there were strong interactions between the race/ethnic group and the presence of these and other individual taxa on risk of preterm birth . By contrast , bacterial vaginosis-associated bacteria (BVAB)-3 was consistently associated with a reduction in the risk of preterm birth for all racial/ethnic groups ( 0.55 ; 95 % CI , 0.39 - 0.78 ) . CONCLUSION BV is characterized by a reduction of Lactobacillus , and lactic acid-producing bacteria and the presence of Mobiluncus ; we found these factors and the presence of Mycoplasma to be associated with an increased risk of preterm birth . By contrast , the presence of a recently identified organism sufficient to cause BV , BVAB3 , decreased the risk of preterm birth . These findings give insight into why treating BV has mixed impact on risk of preterm birth Background Supporting 21st century health care and the practice of evidence -based medicine ( EBM ) requires ubiquitous access to clinical information and to knowledge-based re sources to answer clinical questions . Many questions go unanswered , however , due to lack of skills in formulating questions , crafting effective search strategies , and accessing data bases to identify best levels of evidence . Methods This r and omized trial was design ed as a pilot study to measure the relevancy of search results using three different interfaces for the PubMed search system . Two of the search interfaces utilized a specific framework called PICO , which was design ed to focus clinical questions and to prompt for publication type or type of question asked . The third interface was the st and ard PubMed interface readily available on the Web . Study subjects were recruited from interns and residents on an inpatient general medicine rotation at an academic medical center in the US . Thirty-one subjects were r and omized to one of the three interfaces , given 3 clinical questions , and asked to search PubMed for a set of relevant articles that would provide an answer for each question . The success of the search results was determined by a precision score , which compared the number of relevant or gold st and ard articles retrieved in a result set to the total number of articles retrieved in that set . Results Participants using the PICO templates ( Protocol A or Protocol B ) had higher precision scores for each question than the participants who used Protocol C , the st and ard PubMed Web interface . ( Question 1 : A = 35 % , B = 28 % , C = 20 % ; Question 2 : A = 5 % , B = 6 % , C = 4 % ; Question 3 : A = 1 % , B = 0 % , C = 0 % ) 95 % confidence intervals were calculated for the precision for each question using a lower boundary of zero . However , the 95 % confidence limits were overlapping , suggesting no statistical difference between the groups . Conclusion Due to the small number of search es for each arm , this pilot study could not demonstrate a statistically significant difference between the search protocol s. However there was a trend towards higher precision that needs to be investigated in a larger study to determine if PICO can improve the relevancy of search results Abstract Objective To evaluate whether a screening strategy in pregnancy lowers the rate of preterm delivery in a general population of pregnant women . Design Multicentre , prospect i ve , r and omised controlled trial . Setting Non-hospital based antenatal clinics . Participants 4429 pregnant women presenting for their routine prenatal visits early in the second trimester were screened by Gram stain for asymptomatic vaginal infection . In the intervention group , the women 's obstetricians received the test results and women received st and ard treatment and follow up for any detected infection . In the control group , the results of the vaginal smears were not revealed to the caregivers . Main outcome measures The primary outcome variable was preterm delivery at less than 37 weeks . Secondary outcome variables were preterm delivery at less than 37 weeks combined with different birth weight categories equal to or below 2500 g and the rate of late miscarriage . Results Outcome data were available for 2058 women in the intervention group and 2097 women in the control group . In the intervention group , the number of preterm births was significantly lower than in the control group ( 3.0 % v 5.3 % , 95 % confidence interval 1.2 to 3.6 ; P = 0.0001 ) . Preterm births were also significantly reduced in lower weight categories at less than 37 weeks and ≤ 2500 g. Eight late miscarriages occurred in the intervention group and 15 in the control group . Conclusion Integrating a simple infection screening programme into routine antenatal care leads to a significant reduction in preterm births and reduces the rate of late miscarriage in a general population of pregnant women Objective : To evaluate diagnostic value of vaginal pH and cervical length measurement in the second trimester of pregnancy as a preterm labor ( PTL ) predictor . Methods : During a prospect i ve cohort study 438 uncomplicated singleton pregnant women between 18 and 24 weeks of gestation were assessed regarding vaginal PH and cervical length . Vaginal pH was measured using Ph-indicator strips and cervical length was determined using transvaginal ultrasound . The cut-off values for vaginal PH and cervical length were defined as 5 and < 30 mm respectively . Results : Vaginal pH of 5 and above was found in 162/438 women ( 37 % ) while cervical length < 30 mm was found in 38/438 ( 8.7 % ) . The incidence of PTL < 37 weeks was 87/438 ( 19.9 % ) while the incidence of early ( PTL < 34 weeks ) was 51/438 ( 11.6 % ) . Predictive value of higher vaginal PH was significantly more ( 31 % ) than vaginal PH<5 ( 13 % ) in predicting PTL . As a result , alkaline vaginal PH significantly increases the odds of preterm labor ( OR=3.06 ) . Shortened cervical length is better predictor of PTL than higher vaginal PH with positive predictive value of 71 % and negative predictive value of 85 % . Cervical length less than 30 mm nearly 14-fold increases odds of preterm birth ( OR=13.9 ) . Conclusion : Compared to alkaline vaginal PH , shortened cervical length has better value to predict PTL overall . However , regarding early or late PTL , vaginal PH is more accurate to predict late PTL , while cervical length measurement is more appropriate to predict early PTL ( < 34 weeks ) BACKGROUND Bacterial vaginosis has recently been associated with preterm labor and delivery .  The purpose of our study was to determine whether regular prenatal vaginal pH testing result ed in more frequent diagnoses of bacterial vaginosis and other vaginal infections , more frequent treatment with antibiotics , and fewer preterm deliveries . We also sought to determine the sensitivity and specificity of pH testing and vaginal symptom reporting in identifying vaginal infections . METHODS Our study was a prospect i ve clinical trial involving 121 pregnant women r and omized to receive either st and ard prenatal care , including routine inquiry about vaginal symptoms , or st and ard care supplemented by vaginal pH testing . Women with symptoms or a  vaginal pH level > 4.5 received a wet mount examination . Confirmed infections were treated according to study protocol s. RESULTS Women who received regular pH testing showed significantly higher detection rates for bacterial vaginosis than controls ( 48.4 % vs 27.1 % , P = .015 ) and more frequent detection of Trichomonas vaginalis ( 7.8 % vs 1.7 % , P = .116 ) . A higher percentage of women in the experimental group were treated for bacterial vaginosis and trichomoniasis ( 46.9 % vs 27.1 % , P = .024 ) , and the preterm birth rate was one half that of the control group ( 4.7 % vs 10.2 % , P = .243 ) . The presence of vaginal symptoms or a vaginal pH level > 4.5 identified bacterial vaginosis or trichomoniasis with 84.4 % sensitivity . CONCLUSIONS In our study , frequent vaginal pH testing during pregnancy result ed in more frequent diagnosis and treatment of bacterial vaginosis . Since vaginal symptoms and elevated pH levels appear to be useful in screening for bacterial vaginosis and trichomoniasis , frequent pH testing should be evaluated in larger studies AIM The purpose of this prospect i ve study was to determine the possible association among vaginal fluid pH , cervicovaginitis and cervical length in singleton pregnancies at 16 - 22 weeks of gestation . METHODS A total of 240 asymptomatic singleton pregnancies at 16 - 22 weeks of gestation were included to the study .  Vaginal fluid pH  was determined using pH paper in a sterile speculum examination , and  cervical length was examined by transvaginal ultrasonographic measurement . Vaginitis was diagnosed by pH determination and wet mount smear ; cervicitis was diagnosed by cervical examination . Patients were followed to delivery and hospital records were review ed to extract obstetric information . Preterm delivery was defined as delivery at or prior to 36 weeks of gestation . Abnormal pH was defined as a pH of > 5.0 .  Patients with cervicovaginitis ( n = 72 ) were compared with those without any trace of infection ( n = 60 ) . RESULTS The mean gestational age was 20.3 + /- 1.4 . We found an significant association among cervicovaginitis , cervical length and vaginal pH. There was a significant correlation between an elevated vaginal pH ( > 5.0 ) and a shortened cervical length ( r = -0.59 , p < 0.001 ) . Vaginal fluid pH > 5.0 was associated with increased risk of preterm delivery ( OR 4.3 , 95 % CI 2.0 , 9.3 ; p = 0.001 ) as well as delivering an infant of less than 2,500 g ( OR 4.0 , 95 % CI 1.4 , 11.0 ; p = 0.009 ) . CONCLUSIONS Elevated vaginal fluid pH  in women at 16 - 22 weeks of gestation seems to be associated with a decreased cervical length and increased risk of preterm delivery BACKGROUND We evaluated the importance of measuring early vaginal levels of eight bacterial vaginosis (BV)-associated bacteria , at two points in pregnancy , and the risk of spontaneous preterm delivery ( SPTD )  among pregnant women and the subgroup of pregnant women with a history of preterm delivery ( PTD ) . METHODS This prospect i ve cohort study enrolled women at five urban obstetric practice s at Temple University Hospital in Philadelphia PA . Women with singleton pregnancies less than 16 weeks gestation self-collected vaginal swabs at two points in pregnancy , prior to 16 weeks gestation and between 20 - 24 weeks gestation , to measure the presence and level of eight BV-associated bacteria .  Women were followed-up for gestational age at delivery via medical records . RESULTS Among women reporting a prior PTD , women with higher levels of Leptotrichia/Sneathia species , BVAB1 and Mobiluncus spp . , prior to 16 weeks gestation , were significantly more likely to experience a SPTD . In addition , pregnant women with a prior PTD and increasing levels of Leptotrichia/Sneathia species ( aOR : 9.1 , 95 % CI 1.9 , 42.9 ) , BVAB1 ( aOR : 16.4 , 95 % CI 4.3 , 62.7 ) or Megasphaera phylotype 1 ( aOR : 6.2 , 95 % CI 1.9 , 20.6 ) , through 24 weeks gestation , were significantly more likely to experience an SPTD . Among the overall group of pregnant women , the levels of BV-associated bacteria were not related to SPTD . CONCLUSION Among the group of women reporting a prior PTD , increasing levels of BVAB1 , Leptotrichia/Sneathia species , and Megasphaera phylotype 1 , through mid-pregnancy were related to an increased risk of SPTD Objective : To test the usefulness of  vaginal pH determinations in the prediction of the risk of  preterm delivery at or before 36 weeks of gestation . Methods : This was a prospect i ve study of asymptomatic pregnant women .  Vaginal pH  was determined using pH paper in a sterile speculum 
    Output:
    
Conclusion An increased antenatal vaginal pH > 4.5 may be associated with a higher risk for PTB .
Tweetable abstract Pregnant women with an increased vaginal pH > 4.5 may be at higher risk to experience preterm birth