human
***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: Low maternal prepregnancy BMI is associated with adverse birth outcomes , but the BMI at which risk increases is not well defined . We assessed whether the relationship between prepregnancy BMI and birth outcomes is influenced by the extent to which mothers were underweight in a prospect i ve study in Anhui , China . The women ( n = 575 ) were 20 - 34 y old , married , nulliparous and nonsmokers . All measures of infant growth increased with increasing maternal BMI until a plateau was reached at a BMI of 22 - 23 kg/m2 . Infants born to the 27 % of women who were severely underweight before pregnancy ( BMI < or = 18.5 kg/m2 ) were at increased risk for fetal growth deficits associated with infant morbidity . Compared with a normal BMI , being severely underweight was associated with mean ( + /- SEM ) reductions of 219 + /- 40 g in infant birthweight and 6.7 + /- 1.3 % in the birthweight ratio and an 80 % increase in risk of intrauterine growth restriction [ odds ratio ( OR ) 1.8 ; 95 % CI : 1.0 , 3.3 ; P = 0.05 ] . Being severely underweight was also associated with smaller infant head circumference and lower ponderal index . Being moderately underweight ( 18.5 < BMI < 19.8 kg/m2 ) was not significantly associated with adverse pregnancy outcomes . Gestational age and risk of preterm birth were not associated with maternal BMI . More than half of the women in this study were underweight before pregnancy . Although being moderately underweight was not associated with increased risk of adverse pregnancy outcomes , being severely underweight was an important risk factor for reduced fetal growth BACKGROUND The associations between homocysteine , B vitamin status , and pregnancy outcomes have not been examined prospect ively . OBJECTIVE We assessed the associations of preconception homocysteine and B vitamin status with  preterm birth and birth of low-birth-weight ( LBW ) and small-for-gestational-age ( SGA ) infants in Chinese women . DESIGN This was a case-control study of women aged 21 - 34 y. Preterm cases ( n = 29 ) delivered living infants at < 37 wk gestation ; term controls ( n = 405 ) delivered infants at > or = 37 wk . LBW cases ( n = 33 ) had infants weighing < 2500 g ; normal-birth-weight controls ( n = 390 ) had infants weighing > or = 2500 g. SGA cases ( n = 65 ) had infants below the 10th percentile of weight-for-gestational-age ; appropriate-for-gestational-age controls ( n = 358 ) had infants above this cutoff .  Nonfasting plasma concentrations of homocysteine , folate , and vitamins B-6 and B-12 were measured before conception . RESULTS Elevated homocysteine ( > or = 12.4 micro mol/L ) was associated with a nearly 4-fold higher risk of preterm birth ( OR : 3.6 ; 95 % CI : 1.3 , 10.0 ; P < 0.05 ) . The risk of preterm birth was 60 % lower among women with vitamin B-12 > or = 258 pmol/L than among vitamin B-12-deficient women ( OR : 0.4 ; 95 % CI : 0.2 , 0.9 ; P < 0.05 ) and was 50 % lower among women with vitamin B-6 > or = 30 nmol/L than among vitamin B-6-deficient women ( OR : 0.5 ; 95 % CI : 0.2 , 1.2 ; NS ) . Folate status was not associated with preterm birth , and homocysteine and B vitamin status were not associated with LBW or SGA status . CONCLUSIONS Elevated homocysteine and suboptimal vitamin B-12 and B-6 status may increase the risk of preterm birth . These results need to be confirmed in larger prospect i ve studies BACKGROUND There is a growing interest in periconceptional iron supplementation in developing countries by research ers and policy makers ; however , there are no r and omized controlled trials that examine the effectiveness of this strategy in decreasing  anemia during pregnancy . OBJECTIVE The aim was to determine whether periconceptional iron supplementation reduces anemia during pregnancy . DESIGN A r and omized , double-blind , controlled trial was conducted in rural Bangladesh . Married , nulliparous women were r and omly assigned to receive daily iron and folic acid ( IFA ; 60 mg ferrous fumarate and 400 microg folic acid ) ( n = 134 ) or folic acid ( FA ; 400 microg ) ( n = 138 ) in the form of a powdered supplement added to food . Women were followed until pregnancy or the end of 9 mo . Primary outcomes included hemoglobin , plasma ferritin , and plasma transferrin receptor concentrations . RESULTS Among 88 pregnant women , periconceptional IFA in comparison with FA did not affect anemia or iron status at 15 wk gestation . However , each 1 % increase in adherence was associated with a 10-g/L increase in change in hemoglobin from baseline ( P = 0.03 ) , and those who initiated supplementation at a mean ( + /-SD ) time of 72.9 + /- 57.8 d before conception showed a 7.3-g/L increase in change in hemoglobin from baseline compared with those who initiated supplementation at 26.3 + /- 12.3 d after conception ( P = 0.01 ) . Among 146 nonpregnant women , IFA decreased anemia ( odds ratio : 0.19 ; 95 % CI : 0.04 , 0.95 ) and improved iron stores ( P = 0.001 ) more than did FA . CONCLUSION Good adherence and initiation of supplementation before conception are needed to reduce anemia during early pregnancy . This trial was registered at www . clinical trials.gov as NCT00953134 The study was conducted to evaluate a regional , prospect i ve data base of information on mothers of low birth weight ( LBW ) infants . The data base informs on unidentified or under-reported modifiable risk factors from which evidence -based , targeted community intervention strategies could be design ed to lower the rate of low birth weight in the region . The LBW Registry is based on informed consent , a semi-structured face-to-face ( FTF ) interview with the mother of the newborn LBW infant , medical record review , and birth certificate worksheet data collection . Descriptive statistics were used to summarize data from the registry . High rates of modifiable risk factors among mothers of low birth weight infants ( October 2007–October 2008 ) include smoking ( 44 % ) , alcohol consumption ( 16 % ) , and drug abuse ( 14 % ) . Preconception vitamin use was low ( 34 % ) . The reported use of fertility drugs in FTF interviews was notably higher than information reported on the birth certificate worksheets by the same set of interviewed mothers ( 5.4 vs. 1.5 % ) , as was alcohol use during pregnancy ( 16 vs. 1.3 % ) . More than half ( 52 % ) of the mothers of low birth weight infants reported a vaginal or urinary tract infection during pregnancy . Additionally there were higher than average rates of unmarried mothers ( 62 % ) , unintended pregnancies ( 67 % ) , and Medicaid beneficiaries ( 57 % ) . Mothers repeatedly expressed excessive dem and s in their lives , straining their coping abilities and re sources . The LBW Registry provides exp and ed local data on potentially modifiable risk factors to aid in design ing targeted prevention and intervention strategies OBJECTIVE To determine whether pre-pregnancy body mass index ( BMI ) and gestational weight gain ( GWG ) influence infant postnatal growth . STUDY DESIGN Participants were from the Pregnancy , Infection , and Nutrition study , a prospect i ve pregnancy cohort . Term infants with weight or length measurements at approximately 6 months were included ( n = 363 ) . Multivariable regression estimated associations for weight-for-age ( WAZ ) , length-for-age ( LAZ ) , and weight-for-length z-scores ( WLZ ) and rapid infant weight gain with categorical maternal exposures defined with the 2009 Institute of Medicine recommendations . RESULTS Pre-pregnancy overweight and obesity were associated with higher WAZ ( linear regression coefficient [ β ] , 0.32 ; 95 % CI , 0.04 - 0.61 ) and WLZ ( β , 0.39 ; 95 % CI , 0.02 - 0.76 ) , respectively . Pre-pregnancy BMI was not associated with LAZ . Excessive GWG was associated with higher WAZ ( β , 0.39 ; 95 % CI , 0.15 - 0.62 ) and LAZ ( β , 0.34 ; 95 % CI , 0.12 - 0.56 ) . Excessive GWG ≥ 200 % of recommended amount was associated with higher WAZ ( β , 0.68 ; 95 % CI , 0.28 - 1.07 ) , LAZ ( β , 0.45 ; 95 % CI , 0.06 - 0.83 ) , and WLZ ( β , 0.43 ; 95 % CI , 0.04 - 0.82 ) . Risk of rapid weight gain increased across maternal exposure categories ; however , none of the estimates were significant . CONCLUSIONS Pre-pregnancy BMI and GWG are modifiable intrauterine exposures that influence infant postnatal anthropometric outcomes . Further investigation with infant body composition measurements is warranted OBJECTIVE To assess the association between preconception homocysteine and B vitamin status and risk of clinical spontaneous abortion in women from Anqing , China . METHODS All women were aged 21–34 years , had never smoked , and were primigravid . Patients ( n = 49 ) were women with a clinical ly recognized pregnancy who experienced a fetal death before 100 days ' gestation . Controls ( n = 409 ) were women who maintained a pregnancy that ended in a live birth .  Homocysteine , folate , and vitamins B6 and B12 concentrations were measured in plasma obtained before conception . RESULTS Mean vitamin B6 concentration was lower in patients than in controls ( 34.0 versus 37.9 nmol/L , P = .04 ) . In addition , the risk of spontaneous abortion tended to increase with decreasing plasma vitamin B6 and folate concentration ( P for trend = .06 and .07 , respectively ) , although the significance of these trends was further reduced in logistic models that included age , body mass index , and both vitamins . The risk of spontaneous abortion was four‐fold higher among women with suboptimal plasma concentrations of both folate and vitamin B6 ( folate less than or equal to 8.4 nmol/L and vitamin B6 less than or equal to 49 nmol/L ) than in those with higher plasma concentrations of both vitamins ( odds ratio 4.1 , 95 % confidence interval 1.2 , 14.4 ) . Homocysteine and vitamin B12 status were not associated with spontaneous abortion risk . CONCLUSION Suboptimal preconception folate and vitamin B6 status , especially when they occur together , may increase the risk of clinical spontaneous abortion . Additional prospect i ve studies are needed to confirm these findings and to determine whether antenatal B vitamin supplementation reduces spontaneous abortion risk Maternal vitamin status contributes to clinical spontaneous abortion , but the role of B-vitamin and homocysteine status in sub clinical early pregnancy loss is unknown . Three-hundred sixty-four textile workers from Anqing , China , who conceived at least once during prospect i ve observation ( 1996 - 1998 ) , provided daily urine specimens for up to 1 year , and urinary human chorionic gonadotropin was assayed to detect conception and early pregnancy loss .  Homocysteine , folate , and vitamins B6 and B12 were measured in preconception plasma . Relative to women in the lowest quartile of vitamin B6 , those in the third and fourth quartiles had higher adjusted proportional hazard ratios of conception ( hazard ratio (HR)=2.2 , 95 % confidence interval ( CI ) : 1.3 , 3.4 ; HR=1.6 , 95 % CI : 1.1 , 2.3 , respectively ) , and the adjusted odds ratio for early pregnancy loss in conceptive cycles was lower in the fourth quartile ( odds ratio=0.5 , 95 % CI : 0.3 , 1.0 ) . Women with sufficient vitamin B6 had a higher adjusted hazard ratio of conception ( HR=1.4 , 95 % CI : 1.1 , 1.9 ) and a lower adjusted odds ratio of early pregnancy loss in conceptive cycles ( odds ratio=0.7 , 95 % CI : 0.4 , 1.1 ) than did women with vitamin B6 deficiency . Poor vitamin B6 status appears to decrease the probability of conception and to contribute to the risk of early pregnancy loss in this population OBJECTIVE To examine the association between gestational weight gain and maternal body mass index ( BMI ) among Vietnamese women and the risk of delivering an infant too small or too large for gestational age . METHODS 
    Output:
    
agent
***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: Low maternal prepregnancy BMI is associated with adverse birth outcomes , but the BMI at which risk increases is not well defined . We assessed whether the relationship between prepregnancy BMI and birth outcomes is influenced by the extent to which mothers were underweight in a prospect i ve study in Anhui , China . The women ( n = 575 ) were 20 - 34 y old , married , nulliparous and nonsmokers . All measures of infant growth increased with increasing maternal BMI until a plateau was reached at a BMI of 22 - 23 kg/m2 . Infants born to the 27 % of women who were severely underweight before pregnancy ( BMI < or = 18.5 kg/m2 ) were at increased risk for fetal growth deficits associated with infant morbidity . Compared with a normal BMI , being severely underweight was associated with mean ( + /- SEM ) reductions of 219 + /- 40 g in infant birthweight and 6.7 + /- 1.3 % in the birthweight ratio and an 80 % increase in risk of intrauterine growth restriction [ odds ratio ( OR ) 1.8 ; 95 % CI : 1.0 , 3.3 ; P = 0.05 ] . Being severely underweight was also associated with smaller infant head circumference and lower ponderal index . Being moderately underweight ( 18.5 < BMI < 19.8 kg/m2 ) was not significantly associated with adverse pregnancy outcomes . Gestational age and risk of preterm birth were not associated with maternal BMI . More than half of the women in this study were underweight before pregnancy . Although being moderately underweight was not associated with increased risk of adverse pregnancy outcomes , being severely underweight was an important risk factor for reduced fetal growth BACKGROUND The associations between homocysteine , B vitamin status , and pregnancy outcomes have not been examined prospect ively . OBJECTIVE We assessed the associations of preconception homocysteine and B vitamin status with  preterm birth and birth of low-birth-weight ( LBW ) and small-for-gestational-age ( SGA ) infants in Chinese women . DESIGN This was a case-control study of women aged 21 - 34 y. Preterm cases ( n = 29 ) delivered living infants at < 37 wk gestation ; term controls ( n = 405 ) delivered infants at > or = 37 wk . LBW cases ( n = 33 ) had infants weighing < 2500 g ; normal-birth-weight controls ( n = 390 ) had infants weighing > or = 2500 g. SGA cases ( n = 65 ) had infants below the 10th percentile of weight-for-gestational-age ; appropriate-for-gestational-age controls ( n = 358 ) had infants above this cutoff .  Nonfasting plasma concentrations of homocysteine , folate , and vitamins B-6 and B-12 were measured before conception . RESULTS Elevated homocysteine ( > or = 12.4 micro mol/L ) was associated with a nearly 4-fold higher risk of preterm birth ( OR : 3.6 ; 95 % CI : 1.3 , 10.0 ; P < 0.05 ) . The risk of preterm birth was 60 % lower among women with vitamin B-12 > or = 258 pmol/L than among vitamin B-12-deficient women ( OR : 0.4 ; 95 % CI : 0.2 , 0.9 ; P < 0.05 ) and was 50 % lower among women with vitamin B-6 > or = 30 nmol/L than among vitamin B-6-deficient women ( OR : 0.5 ; 95 % CI : 0.2 , 1.2 ; NS ) . Folate status was not associated with preterm birth , and homocysteine and B vitamin status were not associated with LBW or SGA status . CONCLUSIONS Elevated homocysteine and suboptimal vitamin B-12 and B-6 status may increase the risk of preterm birth . These results need to be confirmed in larger prospect i ve studies BACKGROUND There is a growing interest in periconceptional iron supplementation in developing countries by research ers and policy makers ; however , there are no r and omized controlled trials that examine the effectiveness of this strategy in decreasing  anemia during pregnancy . OBJECTIVE The aim was to determine whether periconceptional iron supplementation reduces anemia during pregnancy . DESIGN A r and omized , double-blind , controlled trial was conducted in rural Bangladesh . Married , nulliparous women were r and omly assigned to receive daily iron and folic acid ( IFA ; 60 mg ferrous fumarate and 400 microg folic acid ) ( n = 134 ) or folic acid ( FA ; 400 microg ) ( n = 138 ) in the form of a powdered supplement added to food . Women were followed until pregnancy or the end of 9 mo . Primary outcomes included hemoglobin , plasma ferritin , and plasma transferrin receptor concentrations . RESULTS Among 88 pregnant women , periconceptional IFA in comparison with FA did not affect anemia or iron status at 15 wk gestation . However , each 1 % increase in adherence was associated with a 10-g/L increase in change in hemoglobin from baseline ( P = 0.03 ) , and those who initiated supplementation at a mean ( + /-SD ) time of 72.9 + /- 57.8 d before conception showed a 7.3-g/L increase in change in hemoglobin from baseline compared with those who initiated supplementation at 26.3 + /- 12.3 d after conception ( P = 0.01 ) . Among 146 nonpregnant women , IFA decreased anemia ( odds ratio : 0.19 ; 95 % CI : 0.04 , 0.95 ) and improved iron stores ( P = 0.001 ) more than did FA . CONCLUSION Good adherence and initiation of supplementation before conception are needed to reduce anemia during early pregnancy . This trial was registered at www . clinical trials.gov as NCT00953134 The study was conducted to evaluate a regional , prospect i ve data base of information on mothers of low birth weight ( LBW ) infants . The data base informs on unidentified or under-reported modifiable risk factors from which evidence -based , targeted community intervention strategies could be design ed to lower the rate of low birth weight in the region . The LBW Registry is based on informed consent , a semi-structured face-to-face ( FTF ) interview with the mother of the newborn LBW infant , medical record review , and birth certificate worksheet data collection . Descriptive statistics were used to summarize data from the registry . High rates of modifiable risk factors among mothers of low birth weight infants ( October 2007–October 2008 ) include smoking ( 44 % ) , alcohol consumption ( 16 % ) , and drug abuse ( 14 % ) . Preconception vitamin use was low ( 34 % ) . The reported use of fertility drugs in FTF interviews was notably higher than information reported on the birth certificate worksheets by the same set of interviewed mothers ( 5.4 vs. 1.5 % ) , as was alcohol use during pregnancy ( 16 vs. 1.3 % ) . More than half ( 52 % ) of the mothers of low birth weight infants reported a vaginal or urinary tract infection during pregnancy . Additionally there were higher than average rates of unmarried mothers ( 62 % ) , unintended pregnancies ( 67 % ) , and Medicaid beneficiaries ( 57 % ) . Mothers repeatedly expressed excessive dem and s in their lives , straining their coping abilities and re sources . The LBW Registry provides exp and ed local data on potentially modifiable risk factors to aid in design ing targeted prevention and intervention strategies OBJECTIVE To determine whether pre-pregnancy body mass index ( BMI ) and gestational weight gain ( GWG ) influence infant postnatal growth . STUDY DESIGN Participants were from the Pregnancy , Infection , and Nutrition study , a prospect i ve pregnancy cohort . Term infants with weight or length measurements at approximately 6 months were included ( n = 363 ) . Multivariable regression estimated associations for weight-for-age ( WAZ ) , length-for-age ( LAZ ) , and weight-for-length z-scores ( WLZ ) and rapid infant weight gain with categorical maternal exposures defined with the 2009 Institute of Medicine recommendations . RESULTS Pre-pregnancy overweight and obesity were associated with higher WAZ ( linear regression coefficient [ β ] , 0.32 ; 95 % CI , 0.04 - 0.61 ) and WLZ ( β , 0.39 ; 95 % CI , 0.02 - 0.76 ) , respectively . Pre-pregnancy BMI was not associated with LAZ . Excessive GWG was associated with higher WAZ ( β , 0.39 ; 95 % CI , 0.15 - 0.62 ) and LAZ ( β , 0.34 ; 95 % CI , 0.12 - 0.56 ) . Excessive GWG ≥ 200 % of recommended amount was associated with higher WAZ ( β , 0.68 ; 95 % CI , 0.28 - 1.07 ) , LAZ ( β , 0.45 ; 95 % CI , 0.06 - 0.83 ) , and WLZ ( β , 0.43 ; 95 % CI , 0.04 - 0.82 ) . Risk of rapid weight gain increased across maternal exposure categories ; however , none of the estimates were significant . CONCLUSIONS Pre-pregnancy BMI and GWG are modifiable intrauterine exposures that influence infant postnatal anthropometric outcomes . Further investigation with infant body composition measurements is warranted OBJECTIVE To assess the association between preconception homocysteine and B vitamin status and risk of clinical spontaneous abortion in women from Anqing , China . METHODS All women were aged 21–34 years , had never smoked , and were primigravid . Patients ( n = 49 ) were women with a clinical ly recognized pregnancy who experienced a fetal death before 100 days ' gestation . Controls ( n = 409 ) were women who maintained a pregnancy that ended in a live birth .  Homocysteine , folate , and vitamins B6 and B12 concentrations were measured in plasma obtained before conception . RESULTS Mean vitamin B6 concentration was lower in patients than in controls ( 34.0 versus 37.9 nmol/L , P = .04 ) . In addition , the risk of spontaneous abortion tended to increase with decreasing plasma vitamin B6 and folate concentration ( P for trend = .06 and .07 , respectively ) , although the significance of these trends was further reduced in logistic models that included age , body mass index , and both vitamins . The risk of spontaneous abortion was four‐fold higher among women with suboptimal plasma concentrations of both folate and vitamin B6 ( folate less than or equal to 8.4 nmol/L and vitamin B6 less than or equal to 49 nmol/L ) than in those with higher plasma concentrations of both vitamins ( odds ratio 4.1 , 95 % confidence interval 1.2 , 14.4 ) . Homocysteine and vitamin B12 status were not associated with spontaneous abortion risk . CONCLUSION Suboptimal preconception folate and vitamin B6 status , especially when they occur together , may increase the risk of clinical spontaneous abortion . Additional prospect i ve studies are needed to confirm these findings and to determine whether antenatal B vitamin supplementation reduces spontaneous abortion risk Maternal vitamin status contributes to clinical spontaneous abortion , but the role of B-vitamin and homocysteine status in sub clinical early pregnancy loss is unknown . Three-hundred sixty-four textile workers from Anqing , China , who conceived at least once during prospect i ve observation ( 1996 - 1998 ) , provided daily urine specimens for up to 1 year , and urinary human chorionic gonadotropin was assayed to detect conception and early pregnancy loss .  Homocysteine , folate , and vitamins B6 and B12 were measured in preconception plasma . Relative to women in the lowest quartile of vitamin B6 , those in the third and fourth quartiles had higher adjusted proportional hazard ratios of conception ( hazard ratio (HR)=2.2 , 95 % confidence interval ( CI ) : 1.3 , 3.4 ; HR=1.6 , 95 % CI : 1.1 , 2.3 , respectively ) , and the adjusted odds ratio for early pregnancy loss in conceptive cycles was lower in the fourth quartile ( odds ratio=0.5 , 95 % CI : 0.3 , 1.0 ) . Women with sufficient vitamin B6 had a higher adjusted hazard ratio of conception ( HR=1.4 , 95 % CI : 1.1 , 1.9 ) and a lower adjusted odds ratio of early pregnancy loss in conceptive cycles ( odds ratio=0.7 , 95 % CI : 0.4 , 1.1 ) than did women with vitamin B6 deficiency . Poor vitamin B6 status appears to decrease the probability of conception and to contribute to the risk of early pregnancy loss in this population OBJECTIVE To examine the association between gestational weight gain and maternal body mass index ( BMI ) among Vietnamese women and the risk of delivering an infant too small or too large for gestational age . METHODS 
    Output:
    