***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 Published data on pregnancy outcome after exposure to H2-blockers  is scarce . The aim of the present study was to evaluate the data collected by the memberships of the European Network of Teratology Information Services ( ENTIS ) . METHODS The patients were pregnant women who or whose doctor or midwife did contact a Teratology Information Service for risk assessment after the use of a H2-blocker in pregnancy . The data were prospect ively collected , i.e. before the outcome of pregnancy was known . St and ardized procedures for data collection were used by each centre . The data of the exposed women were compared to those of a control group exposed to non-teratogenic substances . RESULTS Data on the outcome of 553 pregnancies with exposure to an H2-blocker were evaluated ( ranitidine n=335 ; cimetidine n=113 , famotidine n=75 ; nizatidine n=15 , roxatidine n=15 ) . Most of them had been exposed at least in the first trimester . The incidence of premature deliveries was higher in the exposed group compared to the control group . There was no increase in the incidence of major malformations . Two pregnancies with maternal use of famotidine in early pregnancy were terminated after the prenatal diagnosis of a neural tube defect . CONCLUSION There is no indication for an increased risk of major malformations after the use of H2-blockers during pregnancy A r and omized controlled trial was performed to study the efficacy of Syn-Ergel with an active placebo in the treatment of heartburn of pregnancy in ninety-two patients completing 7 days of therapy .  Syn-Ergel was significantly better ( p 0.001 ) in all groups of pre-treatment pain severity in relieving the symptoms , and had a longer duration of action , than the active placebo .  Complete relief of pain was achieved in 79.5 % of Syn-Ergel treatments with a further 10 % of treatments result ing in marked easing of discomfort at 1 hour following administration . The corresponding figures for the ‘ active placebo ’ were 56 % and 20 % . The combination of an antacid and a protective mucosal coating agent would appear to be a useful approach in the treatment of heartburn of pregnancy Objective To determine whether ranitidine ( Zantac ) taken once or twice daily is effective for relieving symptoms of  gastroesophageal reflux among pregnant women who had failed conservative measures . Methods Volunteers with heartburn despite antacids were sought among our obstetric clinic population for this double-blind , placebo-controlled , triple crossover trial . After a baseline week , 20 patients were r and omized to receive the three following weekly regimens : ranitidine 150 mg twice daily , placebo in the morning and ranitidine 150 mg in the evening , or placebo twice daily . Daily scores on symptom diaries , global assessment s , and number of antacids taken were compared among the 18 patients completing the study . Results The twice-daily dosage of ranitidine was the only regimen found to reduce heartburn symptoms when compared with the baseline ( P < .001 ) or a placebo ( P < .01 ) . Compared with ranitidine taken once daily , the twice-daily dosing prompted less need for antacid tablets compared with the placebo ( P < .05 versus P > .05 ) and to the baseline ( P < .001 versus P < .05 ) . The average reduction of heartburn severity using twice-daily ranitidine was 55.6 % when compared with baseline ( 95 % confidence interval [ CI ] 34.8 % , 76.5 % ) and was 44.2 % when compared with placebo ( 95 % CI 15.4 % , 72.9 % ) . Conclusion This study indicates the efficacy of ranitidine 150 mg taken twice daily , rather than once daily , for relief of gastroesophageal reflux symptoms during pregnancy A double blind comparative study comparing Mucaine , Mucaine without oxethazaine , and placebo was carried out with 50 patients with symptoms of heartburn during late pregnancy . We found that the 2 active treatments were more effective than placebo for the relief of heartburn , but there was no statistically significant difference between groups for the relief of nausea and regurgitation . There was a significant difference in the percentage of days of use of each medication , with the placebo being used least frequently . Although not statistically significant , for the 3 measures for which placebo differed from the active treatments , patients showed a better response to mucaine . This suggests that the addition of oxethazaine may be of benefit . The lack of statistical significance may be due to the relatively small number of cases , and the findings are promising . No side effects were recorded for any treatment A r and omised crossover trial was performed in 55 pregnant women who complained of heartburn  to see whether  alkali or  acid  treatment alleviated it . Each woman was given a week 's treatment with an acid mixture , an alkali mixture , and a placebo in r and omised order . Both acid and alkali mixtures were better than placebo , but there was no significant difference between the acid and alkali treatments . Together with the inconsistent reports of some patients , these findings suggest that both acid reflux and bile regurgitation may cause heartburn in pregnant women and that other factors may also play a part . Because the cause of heartburn may be difficult to determine , treatment should be empirical . If the patient does not respond to seven days ' acid treatment an alkali mixture should be prescribed ; there is a 98 % chance that one of these treatments will relieve symptoms OBJECTIVES This study is aim ed at determining the prevalence of gastrointestinal symptoms among healthy pregnant women attending antenatal clinic at the University of Maiduguri Teaching Hospital . METHODS Question naires were r and omly administered to consecutive antenatal clinic attendees until the sample size was reached . RESULTS Three hundred and seventy pregnant women were interviewed .  Heart burns , easy fullness and nausea were the commonest gastrointestinal symptoms in 45 % , 40.2 % and 39.9 % of cases respectively . Primigravidae had significantly more symptoms than multiparae . There were also significantly more gastrointestinal symptoms in the first trimester of pregnancy . CONCLUSION Gastrointestinal symptoms are common among healthy pregnant women . And even though these represent well-known physiological changes , they must be carefully assessed to exclude any pathological disorder that may require intervention In a double-blind study the gastro-oesophageal sphincter pressure profile was measured in a group of twenty women in the last trimester of pregnancy , all of whom suffered from heartburn . The mean gastric and the maximum sphincter pressures were calculated from the pressure profile , and the difference between these two was defined as the barrier pressure . After resting sphincter measurement ten of the women were given 10 mg metocolopramide intravenously , and the other ten had a placebo intravenous injection ; 15 min later the sphincter pressures were measured again . Metoclopramide significantly increased the mean maximum sphincter and barrier pressures compared to the baseline pressure , and there was no significant difference between the pre- and post-injection pressures in the placebo group . However , the raised mean maximum sphincter and barrier pressures following metoclopramide were made up of four patients having very high pressures and six patients on whom metoclopramine appeared to have little effect . The clinical usefulness of metoclopramide in women in labour is discussed Background : Proton pump inhibitors are used to treat gastro‐oesophageal reflux and peptic ulcers . Gastro‐oesophageal reflux is a common condition in pregnancy . Human pregnancy experience with lansoprazole or pantoprazole is very limited . More data exist on the safety of omeprazole in pregnancy OBJECTIVES To evaluate the magnitude of possible fetal risks involved in maternal use of omeprazole during pregnancy . STUDY DESIGN Infants whose mothers used omeprazole during pregnancy were identified from the Swedish Medical Birth Registry . A total of 955 exposed infants born in 1995 - 1999 were identified : 863 of which were exposed in early pregnancy and 131 later in pregnancy and 39 who had been exposed both in early and late pregnancy . Delivery outcome was studied : presence of congenital malformations , perinatal survival , low birth weight , low Apgar score and hospitalization up to the end of 1997 . RESULTS No clear-cut indication of ill effects were seen . Five infants were stillborn and the rate of congenital heart defects was slightly increased , but both effects may be r and om . CONCLUSIONS The present data set and previously published data give no reason for concern after exposure for omeprazole during pregnancy 
    Output:
    
There was little information to draw conclusions on the overall effectiveness of interventions to relieve heartburn in pregnancy