***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 In third world countries the length of breastfeeding often has a major influence on child mortality , morbidity and nutritional status . When evaluating the impact of length of breastfeeding the reason why a mother terminates breastfeeding is usually not taken into consideration . METHODS Risk factors for termination of breastfeeding were studied in a prospect i ve community study following 1678 children in Guinea Bissau , West Africa from birth to cessation of breastfeeding , migration or death . RESULTS The median weaning age  was 22.6 months . Illness of the child , new pregnancy of the mother and illness of the mother were associated with significantly shorter lactation period compared with children weaned because they were ' healthy ' or ' old enough ' . These explanations had an impact independent of other determinants for weaning , including ethnic group , mother 's age , mother 's education , birth order and number of dead siblings . Weaning before 12 months of age was only associated with illness of the mother or child and new pregnancy and not with any socioeconomic or cultural factors . CONCLUSIONS Health workers should pay special attention to the encouragement of breastfeeding in connection with illness of the mother or child ; these considerations may also be important in the planning of breastfeeding promotion campaigns . Since premature termination of breastfeeding is associated with new pregnancy , family planning should be part of any breastfeeding promotion programme In order to identify the reasons for early weaning in Teheran , we interviewed 900 mothers using a systematic r and omized sampling method . A total of 15 % of the mothers were illiterate , 93 % were housewives , and 97 % had given birth in hospitals . Only 3 % of the newborns benefited from rooming-in facilities in hospital , and 68 % were bottle-fed while still in hospital . In 3.1 % of cases the mother had not breast-fed her newborn at all . Of those who had breast-fed their infant , 38 % used only their own milk , whereas 62 % used a combination of breast milk and infant formula . The median duration of breast-feeding was 16 months ( mean , 14 months ) . A total of 74 % of mothers who used supplementary formula and 39 % of those who had completely stopped breast-feeding blamed milk insufficiency , although 67 % of these mothers had reached this conclusion only because their infants cried or were irritable . The following factors had a negative influence on the duration of breast-feeding : use of supplementary formula and of estrogen-containing oral contraceptives ; fathers with high incomes ; and mothers with a high educational level . In contrast , the mother 's religious motive to breast-feed and her insistence on breast-feeding had a positive impact . Unfortunately , 21 % of the mothers started using supplementary formula during the first month postpartum , and two-thirds before the end of the fourth month . Every month that bottle-feeding was started prematurely shortened the duration of breast-feeding by 20 days . ( ABSTRACT TRUNCATED AT 250 WORDS A prospect i ve study of breast-feeding mothers was undertaken to determine the effect of formula sample s and other hospital-related factors on success in  breast-feeding .  Of the 166 nursing mothers studied for 4 months postpartum , 83 % breast-fed for 1 month , 73 % for 10 weeks , and 58 % for 4 months or longer . Breast-feeding duration was not affected by formula sample s given at discharge from the hospital . Factors correlating significantly with improved breast-feeding rates include maternal age , maternal education , nonsmoking , previous breast-feeding , planned pregnancy , initiation of breast-feeding in the first 16 hours , and minimization of formula supplementation in the nursery . Partial breast-feeding ( supplementing more than one bottle of formula per day , measured at 1 month postpartum ) was associated with shorter breast-feeding duration . This latter effect was minimized by frequent nursing ( seven or more times per day ) , despite formula supplementation A multicenter study of the Lactational Amenorrhea Method ( LAM )  was carried out to test the acceptability and efficacy of the method . Additionally , the data are used to test new constructs for improvement of method criteria . A protocol was design ed at the Institute for Reproductive Health ( IRH ) , Department of Obstetrics and Gynecology , Georgetown University Medical Center , a World Health Organization ( WHO ) Collaborating Center , and was review ed and modified in collaboration with the co-sponsors , the World Health Organization and the South to South Cooperation for Reproductive Health , and the principal investigators from each site . Data were gathered prospect ively on  LAM acceptors at 11 sites . Data were entered and cleaned on-site and further cleaned and analyzed at IRH , using country-level and pooled data to produce descriptive statistics and life tables . The 98+% efficacy of LAM is confirmed in a wide variety of setting s. In addition , the results yield insight on the possibility of continued use beyond 6 months . LAM is found to be highly effective as an introductory postpartum method when offered in a variety of cultures , health care setting s , socio-economic strata , and industrial and developing country locales . In addition , LAM  acceptance complements breastfeeding behaviors without ongoing breastfeeding support services . The parameters studied yield high efficacy and method continuation . Therefore , the basic tenets of the 1995 Bellagio consensus on LAM is reconfirmed and it is recommended that LAM be reconfirmed and it is recommended that LAM be incorporated into hospital , maternity , family planning , maternal and child health , and other primary health care setting The association between breast-feeding patterns and resumption of menses post-partum was examined in a prospect i ve study in Indonesia . In order to examine these relationships directly in a longitudinal study , it was first necessary to distinguish among women who experienced infant mortality before menses resumed , women who weaned before menses resumed , and women who had return to menses while breast-feeding . Information on suckling patterns and menstrual status was collected by recall for 444 women at monthly visits for 2 years . Three main breast-feeding variables , minutes per episode , number of episodes per day , number of episodes per night , and other breast-feeding variables were derived for each woman , to give the average nursing pattern up to menses or the end of the study , which-ever came first . While high levels of nursing for each of these three main variables were found to be significantly related to delay in return of menses post-partum , the interactions between more minutes per episode , and more frequent day- and night-time feeds , were found to be the most important factors in the delay in onset of post-partum menstruation in those women whose menses resumed while still nursing or who remained amenorrhoeic and nursing at the end of the study This report presents a secondary data analysis based on prospect ively collected records gathered during a field assessment that was carried out in Rw and a in August 1993 . The assessment used service statistics and follow-up interviews to evaluate the efficacy of a modified lactational amenorrhea method ( LAM ) as a nine-month introductory postpartum natural family planning method . The program , carried out by Action Familiale Rw and aise ( AFR ) , reflects high efficacy of the method in a compliant sample that sought this method followed by another form of family planning . These results are promising and provide guidance for the extended use of LAM past six months . Programmatic findings suggest that studies be conducted of the contribution of extended LAM to improved weaning practice s , the high efficacy of continued reliance on substantial lactation and amenorrhea beyond nine months , and male involvement in LAM and breastfeeding BACKGROUND The use of breastfeeding as a method of birth spacing occasionally ends in " unplanned pregnancy . " This is due to unexpected expiration of one or more of the lactation amenorrhea method ( LAM ) prerequisites . The current study tests a new concept that the in-advance provision of single packet of progestogen emergency contraception ( EC ) pills during the postpartum LAM counseling may decrease the incidence of unplanned pregnancy during breastfeeding . STUDY DESIGN This was a registered two-armed r and omized controlled trial ( NCT 01111929 ) . Women intending to breastfeed and to postpone pregnancy for 1 year or more were approached . They received adequate postpartum contraceptive counseling . Women intending to use LAM were r and omly assigned to one of two groups . The LAM-only group received the proper LAM counseling and did not receive counseling about EC . The LAM-EC group received counseling for both LAM and EC with in-advance provision of one packet of EC pills . They were advised to use these pills if one of the prerequisites of LAM expires and sexual relation has occurred before the initiation of another regular contraceptive protection . All the participants were advised that they need to use another regular method upon expiration of any of the LAM prerequisites . RESULTS Eligible women were 1158 parturients r and omized into two equal groups . Forty-four percent of the women provided with EC used them . Significantly more women in the LAM-EC group initiated regular contraception within or shortly after the first 6 months postpartum when compared with those in the LAM-only group ( 30.5 % vs. 7.3 % , respectively ; p=.0004 ) . Pregnancy occurred in 5 % of the LAM-only group as compared with 0.8 % in the LAM-EC group ( p=.005 ) . Minimal side effects were reported after EC use . CONCLUSION In-advance provision of EC pills can increase the rate of initiation of regular contraception once one or more of the prerequisites of LAM expire . Consequently , the use of EC pills as a temporary backup of LAM can decrease the incidence of unplanned pregnancy during breastfeeding . The use of progestogen EC pill during lactation is safe and tolerable BACKGROUND In the hierarchy of research design s , the results of r and omized , controlled trials are considered to be evidence of the highest grade , whereas observational studies are viewed as having less validity because they reportedly overestimate treatment effects . We used published meta-analyses to identify  r and omized clinical trials and observational studies that examined the same clinical topics . We then compared the results of the original reports according to the type of research design . METHODS A search of the Medline data base for articles published in five major medical journals from 1991 to 1995 identified meta-analyses of r and omized , controlled trials and meta-analyses  of either cohort or case-control studies that assessed the same intervention . For each of five topics , summary estimates and 95 percent confidence intervals were calculated on the basis of data from the individual r and omized , controlled trials and the individual observational studies . RESULTS For the five clinical topics and 99 reports evaluated , the average results of the observational studies were remarkably similar to those of the r and omized , controlled trials . For example , analysis of 13 r and omized , controlled trials of the effectiveness of bacille  Calmette-Guérin vaccine in preventing active tuberculosis yielded a relative risk of 0.49 ( 95 percent confidence interval , 0.34 to 0.70 ) among vaccinated patients , as compared with an odds ratio of 0.50 ( 95 percent confidence interval , 0.39 to 0.65 ) from 10 case-control studies . In addition , the range of the point estimates for the effect of vaccination was wider for the r and omized , controlled trials ( 0.20 to 1.56 ) than for the observational studies ( 0.17 to 0.84 ) . CONCLUSIONS The results of well- design ed observational studies ( with either a cohort or a case-control design ) do not systematic ally overestimate the magnitude of the effects of treatment as compared with those in r and omized , controlled trials on the same topic Abstract Objective : To determine the contraceptive efficacy of the  lactational amenorrhoea method . Design : Non-comparative prospect i ve trial . Setting : Urban Manila , the Philippines . Subjects : 485 lower income , educated women with extensive experience of breast feeding . Intervention : Women were offered all available contraceptives for use after birth . Those who chose the lactational amenorrhoea method  were taught the method , screened for the study , and followed for 12 months to determine the risk of pregnancy when the method was used . Main outcome measures : Life table pregnancy rates during correct and incorrect use of the method , censored monthly in the event of sexual abstinence or the use of another contraceptive method . Results : The lactational amenorrhoea method was 99 % effective when used correctly ( that is , during lactational amenorrhoea and full or nearly full breast feeding for up to six months ) . At 12 months the effectiveness during amenorrhoea dropped to 97 % . Conclusions : The lactational amenorrhoea method provided as much protection from pregnancy as non-breast feeding women experience with non-medicated intrauterine devices and barrier methods . The contraceptive effect of lactation can not be attributed to lactational or postpartum abstinence . Key messages Henceforth , data from clinical trials on contra-ceptives must be subject to the rigours of multiple censoring such as applied here . By excluding periods of abstinence from the calculation of risk of pregnancy , the contraceptive protection of the method can not be attributed to postpartum or lac- tational abstinence During the first year post partum , the rate of pregnancy before the return of menses in lactating women was less than 3 The purpose of this study was to assess the efficacy of the lactational amenorrhea method ( LAM ) for family planning among mothers who are separated from their infants by work . The study population , 170 urban middle class women who planned to return to work before 120 days postpartum , were interviewed monthly for 6 months postpartum and contacted at 12 months . The study population received clinical support for expressing their milk and exclusively breast-milk feeding the infants and for the use of LAM for 
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We found no clear differences in life table pregnancy rates between women using LAM  and being supported in doing so , and fully breastfeeding amenorrheic women not using any method .
As the length of lactation amenorrhoea in women using LAM differed greatly between the population s studied , and was population specific , it is uncertain whether LAM extends lactational amenorrhoea