***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 
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    ***EXAMPLES*** 
    Input: CONTEXT Lactation is associated with improved glucose and insulin homeostasis , independent of weight change . OBJECTIVE To evaluate the association between lactation history and incidence of type 2 diabetes . DESIGN , SETTING , AND PARTICIPANTS Prospect i ve observational cohort study of 83,585 parous women in the Nurses ' Health Study ( NHS ) and retrospective observational cohort study of 73,418 parous women in the Nurses ' Health Study II ( NHS II ) . MAIN OUTCOME MEASURE Incident cases of type 2 diabetes mellitus . RESULTS In the NHS , 5145 cases of type 2 diabetes were diagnosed during 1,239,709 person-years of follow-up between 1986 and 2002 , and in the NHS II , 1132 cases were diagnosed during 778,876 person-years of follow-up between 1989 and 2001 . Among parous women , increasing duration of lactation was associated with a reduced risk of type 2 diabetes . For each additional year of lactation , women with a birth in the prior 15 years had a decrease in the risk of diabetes of 15 % ( 95 % confidence interval , 1%-27 % ) among NHS participants and of 14 % ( 95 % confidence interval , 7%-21 % ) among NHS II participants , controlling for current body mass index and other relevant risk factors for type 2 diabetes . CONCLUSIONS Longer duration of breastfeeding was associated with reduced incidence of type 2 diabetes in 2 large US cohorts of women . Lactation may reduce risk of type 2 diabetes in young and middle-aged women by improving glucose homeostasis The incidence of breast cancer among Japanese women is substantially increasing . This population -based prospect i ve cohort study in Japan evaluated the associations of reproductive factors and exogenous female hormone use with breast cancer risk , both overall and separately among premenopausal and postmenopausal women . A total of 24,064 women aged 40–64 were followed from 1990 to 2003 . During 309,424 person-years of follow-up , 285 breast cancer cases were documented . In overall evaluation , nulliparity was significantly associated with an increased risk of breast cancer . There was a significant decrease in risk with increasing parity number among parous women ( trend P = 0.008 ) . No association was observed between age at menarche or age at first birth and breast cancer risk . Neither oral contraceptive ( OC ) use nor the use of exogenous female hormones other than OC was associated with breast cancer risk . The evaluation according to menopausal status revealed that nulliparity and parity number were significantly related to breast cancer risk only among postmenopausal women . Later age at natural menopause was associated with an increased risk of breast cancer among postmenopausal women ( trend P = 0.02 ) . Our findings suggest that parity number and age at menopause have great effects on breast cancer risk among Japanese women BACKGROUND Breast cancer has been increased in South East Asia countries , but there are limited data for breast cancer risk factors in these countries . To clarify the risk for breast cancer among the Malaysian women , a matched case-control study was conducted . METHOD Between October 2009 and April 2010 , a survey was prospect ively conducted among women admitted to clinics of Penang General Hospital for examination and /or treatment by using a question naire . Therefore , characteristics of patients diagnosed with breast cancer ( n=150 ) were compared with control cases ( n=150 ) admitted to hospital for non-neoplastic , non-hormone related diseases . RESULTS Family history of a distant relative with breast cancer ( OR=2.84 ) , history of first-degree relatives with breast cancer ( OR=2.95 ) , history of benign breast disease ( OR=2.43 ) , menstrual irregularity ( OR=4.24 ) , and use of oral contraceptive pills ( OCP ) ( OR=2.15 ) were found to be significant risk factors for breast cancer in our population . Furthermore , education more than 11 years ( OR=0.40 ) , breastfeeding ( OR=0.50 ) , being employed ( OR=0.45 ) and practicing low fat diet  ( OR=0.53 ) were strongly protective against breast cancer development . CONCLUSION The results emphasize the importance of conducting a series of awareness campaigns that highlights the protective role of longer breastfeeding period against breast cancer and the negative relationships between OCP use and high fat diet with this disease A hospital-based case-control study of ovarian cancer was conducted in London and Oxford between October 1978 and February 1983 .  Menstrual characteristics , reproductive and contraceptive history and history of exposure to various environmental factors were compared between 235 women with histologically diagnosed epithelial ovarian cancer and 451 controls . High gravidity , hysterectomy , female sterilisation and oral contraceptive use were associated with a reduced risk of ovarian cancer . Infertility and late age at menopause were associated with an increase in risk . While these factors were related , they were each found to be independently associated with ovarian cancer risk after adjusting for the effect of the other factors Background Breast cancer has been increased in developing countries , but there are limited data for breast cancer risk factors in these countries . To clarify the risk for breast cancer among the Turkish women , an university hospital based nested case-control study was conducted . Methods Between January 2000 and December 2006 , a survey was prospect ively conducted among women admitted to clinics of Istanbul Medical Faculty for examination and /or treatment by using a question naire . Therefore , characteristics of patients diagnosed with breast cancer ( n = 1492 ) were compared with control cases ( n = 2167 ) admitted to hospital for non-neoplastic , non-hormone related diseases . Results Breast cancer risk was found to be increased in women with age ( ≥ 50 ) [ 95 % confidence interval ( CI ) 2.42–3.18 ] , induced abortion ( 95 % CI 1.13–1.53 ) , age at first birth ( ≥ 35 ) ( 95 % CI 1.62–5.77 ) , body mass index ( BMI ≥ 25 ) ( 95 % CI 1.27–1.68 ) , and a positive family history ( 95 % CI 1.11–1.92 ) . However , decreased breast cancer risk was associated with the duration of education ( ≥ 13 years ) ( 95 % CI 0.62–0.81 ) , presence of spontaneous abortion ( 95 % CI 0.60–0.85 ) , smoking ( 95 % CI 0.61–0.85 ) , breast feeding ( 95 % CI 0.11–0.27 ) , nulliparity ( 95 % CI 0.92–0.98 ) , hormone replacement therapy ( HRT ) ( 95 % CI 0.26–0.47 ) , and oral contraceptive use ( 95 % CI 0.50–0.69 ) . On multivariable logistic regression analysis , age ( ≥ 50 ) years ( OR 2.61 , 95 % CI 2.20–3.11 ) , induced abortion ( OR 1.66 , 95 % CI 1.38–1.99 ) , and oral contraceptive use ( OR 0.60 , 95 % CI 0.48–0.74 ) were found to be associated with breast cancer risk as statistically significant independent factors . Conclusion These findings suggest that age and induced abortion were found to be significantly associated with increased breast cancer risk whereas oral contraceptive use was observed to be associated with decreased breast cancer risk among Turkish women in Istanbul BACKGROUND Findings from observational studies suggest an inverse association between lactation and premenopausal breast cancer risk , but results are inconsistent , and data from large prospect i ve cohort studies are lacking . METHODS We used information from 60,075 parous women participating in the prospect i ve cohort study of the Nurses ' Health Study II from 1997 to 2005 . Our primary outcome was incident premenopausal breast cancer . RESULTS We ascertained 608 incident cases of premenopausal breast cancer during 357,556 person-years of follow-up . Women who had ever breastfed had a covariate-adjusted hazard ratio ( HR ) of 0.75 ( 95 % confidence interval [ CI ] , 0.56 - 1.00 ) for premenopausal breast cancer compared with women who had never breastfed . No linear trend was found with duration of total lactation ( P = .95 ) , exclusive lactation ( P = .74 ) , or lactation amenorrhea ( P = .88 ) . The association between lactation and premenopausal breast cancer was modified by family history of breast cancer ( P value for interaction = .03 ) . Among women with a first-degree relative with breast cancer , those who had ever breastfed had a covariate-adjusted HR of 0.41 ( 95 % CI , 0.22 - 0.75 ) for premenopausal breast cancer compared with women who had never breastfed , whereas no association was observed among women without a family history of breast cancer . CONCLUSION In this large , prospect i ve cohort study of parous premenopausal women , having ever breastfed was inversely associated with incidence of breast cancer among women with a family history of breast cancer Lactational  amenorrhea  ( LA ) is associated with postpartum infertility and is known to be related to breast-feeding frequency and duration , but the exact role of complementary feeding of the infant has not been clearly defined . Data on LA were collected during and after a 2-mo intervention trial in which low-income Honduran women who had breast-fed fully for 4 mo were r and omly assigned to one of three groups : continued full breast-feeding until 6 mo ( FBF , n = 50 ) , introduction of complementary foods at 4 mo with ad libitum breast-feeding from 4 to 6 mo ( SF , n = 47 ) , or introduction of complementary foods at 4 mo with maintenance of baseline breast-feeding frequency from 4 to 6 mo ( SF-M , n = 44 ) . Women were followed up until the infant was 12 mo of age , or later if menses had not occurred by then . All but six of the women continued to breast-feed for > or = 12 mo . With the exclusion of those whose menses returned before 18 wk postpartum ( which could not have been due to the intervention ) , the proportion of women who were amenorrheic at 6 mo was 64.5 % in the SF group , 80.0 % in the FBF group , and 85.7 % in the SF-M group ( chi-square test = 4.13 , P = 0.02 ; one-tailed test with the latter two groups combined ) . The total duration of LA did not differ significantly among groups . The most significant determinant of LA was time spent breast-feeding ( min/d ) , which was in turn negatively associated ( P = 0.06 ) with the infant 's energy intake from complementary foods in regression analyses . These results indicate that there is a significant effect of introducing foods at 4 mo on the likelihood of amenorrhea at 6 mo postpartum , but not thereafter , and that this effect is not seen in mothers who maintain breast-feeding frequency The aim of this study was to evaluate the risk factors for invasive primary epithelial ovarian cancer among Japanese women . In 1990 - 1994 , 45,748 women aged 40 - 69 years were enrolled in the Japan Public Health Center-based Prospect i ve Study cohort . Only 86 epithelial ovarian cancer cases were diagnosed during follow-up through 2008 , reflecting the low ovarian cancer incidence rates in Japan . Cox proportional hazard models were used to estimate hazard ratios ( HR ) and 95 % confidence intervals ( CI ) according to the exposure of interest . The median age at epithelial ovarian cancer  diagnosis was 59 years , with a median follow-up before diagnosis of 7.6 years . There were no statistically significant associations for age at menarche or first birth , breastfeeding , use of exogenous hormones , menopausal status at cohort enrollment , height , body mass index , smoking status , second-h and smoke , alcohol consumption , physical activity and family history of cancer in a first-degree relative . The linear decrease in HR associated with each additional birth was 0.75 ( 95 % CI 0.56 - 0.99 ) . Among women who usually slept > 7 h per day , an HR of 0.4 ( 95 % CI 0.2 - 0.9 ) emerged compared to those who slept < 6 h. This study did not confirm risk factors for epithelial ovarian cancer among Japanese women that have been reported in studies carried out elsewhere .  Usual sleep duration  of > 7 h per day was inversely associated with epithelial ovarian cancer risk , which is a novel finding that needs to be confirmed in other studies Borderline ovarian tumors possess many of the same morphological features as their malignant counterparts , but they do not destructively invade the ovarian stroma , and the women in whom they develop generally have a favorable prognosis . Female residents of three urban counties of western Washington diagnosed with serous and mucinous borderline ovarian tumors between 1980 and 1985 ( n = 116 ) were interviewed regarding past reproductive events . A r and om sample of women from the same counties ( n = 158 ) was identified through r and om digit dialing and were interviewed . The risk of these ovarian tumors among women who had given birth to 1 or 2 children  and to 3 
    Output:
    
No conclusive evidence of an association between breastfeeding and bone mineral density was found .
Exclusive breastfeeding and predominant breastfeeding were associated with longer duration of amenorrhoea .
Shorter duration of breastfeeding was associated with higher risk of postpartum depression .
Evidence suggesting an association of breastfeeding with postpartum weight change was lacking .
Conclusion This review supports the hypothesis that breastfeeding is protective against breast and ovarian carcinoma , and exclusive breastfeeding and predominant breastfeeding increase the duration of lactational amenorrhoea .
There is evidence that breastfeeding reduces the risk of type 2 diabetes .
However , an association between breastfeeding and bone mineral density or maternal depression or postpartum weight change was not evident