***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 To evaluate the efficacy and safety of treating HBV-positive mothers with telbivudine in early and middle pregnancy to prevent mother-to-infant HBV transmission . Methods The subject population comprised pregnant women with chronic hepatitis B ( CHB ; n = 188 ) from January 2013 to June 2015 , with HBV DNA ≥1.0 × 107copies/mL and increased alanine aminotransferase levels . Groups A ( n = 62 ) and B ( n = 61 ) were treated with telbivudine starting at 12 weeks or 20–28 weeks after gestation , respectively . Telbivudine was discontinued at postpartum 12 weeks . Group C ( n = 65 ) received no antiviral . All infants were vaccinated with hepatitis B immunoglobulin ( 200 IU ) and HBV vaccine ( 20 with hepatitis B The maternal HBV DNA levels of the groups were compared . Mother-to-infant transmission of HBV was indicated by the presence of HBsAg in infants 7 months after birth . Results Before treatment , the HBV DNA levels of the 3 groups were similar . Before delivery and 12 weeks after delivery , the HBV DNA levels of groups A and B were similar , but both were significantly lower than that of group C ( P < 0.01 , all ) . No infants in groups A and B were HBsAg-positive , but the infection rate of group C was 18.4 % ( P < 0.01 ) . The HBV infection rate of infants was positively associated with the HBV DNA levels of the pregnant mothers . Conclusion Administration of telbivudine to HBV-infected mothers , started during early and middle pregnancy , completely blocked mother-to-infant HBV transmission . Trial registration The study was registered retrospectively on Janurary 25 in 2016 at Chinese Clinical Trial Registry ( ChiCTR-OPC-16007899 ) Infection of hepatitis B virus ( HBV ) occurs in ~10 % of infants of HBV-infected mothers with positive hepatitis B e antigen ( HBeAg ) after immunoprophylaxis . We aim ed to evaluate the safety and efficacy of telbivudine used during late pregnancy for preventing mother-to-child transmission of HBV . We conducted a multicenter prospect i ve cohort study in 5 hospitals from 2012 to 2014 , which enrolled HBV-infected singleton pregnant women with positive HBeAg . By their choice , women were divided into therapy ( telbivudine 600 mg/day , from gestation 28 - 32 weeks to 3 - 4 weeks postpartum ) and control ( no antiviral agent ) groups . Infants received passive-active immunoprophylaxis and follow-up at the age of 7 - 14 months . Totally , 328 pregnant women were included : 149 in the telbivudine group and 179 in the control group .  Baseline HBV DNA levels were similar in the 2 groups ( 7.43 vs 7.37 log10 IU/mL , P = .711 ) . At delivery , HBV DNA levels in the telbivudine and control groups were 3.80 and 7.26 log10 IU/mL , respectively ( P < .0001 ) . Of the infants , 128 ( 85.9 % ) in the telbivudine group and 156 ( 87.2 % ) in the control group were followed up . No infant in the telbivudine group had chronic infection , while 2 ( 1.28 % ) infants in the control group did ( P = .503 ) . Three ( 2.34 % ) infants in the telbivudine group , but none in the control group , had severe congenital or developmental abnormalities ( P = .090 ) . The data indicate that telbivudine may block perinatal HBV transmission . However , larger studies are required to clarify whether anti-HBV therapy in pregnancy is associated with severe adverse effects in the foetuses and infants Telbivudine , an FDA pregnancy category B drug , has been found to reduce hepatitis B virus ( HBV ) perinatal transmission with no safety concerns in infants aged up to 1 year . This study evaluated the long-term efficacy and safety of telbivudine in 214 infants born to 210 pregnant women with chronic hepatitis B infection who were treated with telbivudine during pregnancy ( weeks 20 - 32 of gestation ) . The infants were followed for up to 5 years after birth . The efficacy endpoint was the rate of perinatal transmission , which was established by HBsAg and HBV DNA levels at 7 and 12 months . Safety endpoints included head circumference , weight , height , congenital abnormality and hospitalization rates . In addition , the Denver Developmental Screening Test was performed in 92 r and omly selected infants . None of the 214 infants born to these women were infected with HBV , and all had effective serum hepatitis B surface antibody ( HBsAb ) levels . Compared with Chinese st and ard values , there were few differences in the infants ' mean head circumference , weight , and height values . No birth defects were diagnosed , and the congenital abnormality rate was 0.934 % . Serious adverse events requiring hospitalization occurred in 20 infants ( 9.35 % ) . The qualified Denver Developmental Screening Test rate in 92 infants was 97.82 % , which was comparable to a rate of 92 % in normal Chinese children . Thus , treatment with telbivudine during the second or third trimesters of pregnancy safely blocked perinatal transmission of HBV . Infants born to telbivudine-treated mothers showed normal growth and development during long-term follow-up of up to 5 years BACKGROUND Few data are available regarding the use of tenofovir disoproxil fumarate ( TDF ) during pregnancy for the prevention of mother-to-child transmission of hepatitis B virus ( HBV ) . METHODS In this trial , we included 200 mothers who were positive for hepatitis B e antigen ( HBeAg ) and who had an HBV DNA level higher than 200,000 IU per milliliter . Participants were r and omly assigned , in a 1:1 ratio , to receive usual care without antiviral therapy or to receive TDF ( at an oral dose of 300 mg per day ) from 30 to 32 weeks of gestation until postpartum week 4 ; the participants were followed until postpartum week 28 . All the infants received immunoprophylaxis . The primary outcomes were the rates of mother-to-child transmission and birth defects . The secondary outcomes were the safety of TDF , the percentage of mothers with an HBV DNA level of less than 200,000 IU per milliliter at delivery , and loss or seroconversion of HBeAg or hepatitis B surface antigen at postpartum week 28 . RESULTS At delivery , 68 % of the mothers in the  TDF  group ( 66 of 97 women ) , as compared with 2 % in the control group ( 2 of 100 ) , had an HBV DNA level of less than 200,000 IU per milliliter ( P<0.001 ) . At postpartum week 28 , the rate of mother-to-child transmission was significantly lower in the TDF group than in the control group , both in the intention-to-treat analysis ( with transmission of virus to 5 % of the infants [ 5 of 97 ] vs. 18 % [ 18 of 100 ] , P=0.007 ) and the per- protocol analysis ( with transmission of virus to 0 vs. 7 % [ 6 of 88 ] , P=0.01 ) . The maternal and infant safety profiles were similar in the TDF group and the control group , including birth-defect rates ( 2 % [ 2 of 95 infants ] and 1 % [ 1 of 88 ] , respectively ; P=1.00 ) , although more mothers in the TDF group had an increase in the creatine kinase level . After the discontinuation of TDF , alanine aminotransferase elevations above the normal range occurred more frequently in mothers in the  TDF group than in those in the control group ( 45 % [ 44 of 97 women ] vs. 30 % [ 30 of 100 ] , P=0.03 ) . The maternal HBV serologic outcomes did not differ significantly between the groups . CONCLUSIONS In a cohort of HBeAg-positive mothers with an HBV DNA level of more than 200,000 IU per milliliter during the third trimester , the rate of mother-to-child transmission was lower among those who received TDF therapy than among those who received usual care without antiviral therapy . ( Funded by Gilead Sciences ; Clinical Trials.gov number , NCT01488526 . ) Women with chronic hepatitis B should maintain nucleotide analogue treatment to prevent disease progression during pregnancy . The aim of this study was to prospect ively evaluate the efficacy and safety of telbivudine used throughout pregnancy for preventing hepatitis B virus ( HBV ) mother-to-child transmission ( MTCT ) . From January 2012 to June 2014 , women who were receiving telbivudine therapy and became pregnant were enrolled in group A at 28 weeks of gestation . Pregnant women with an HBV DNA level > 106 IU/mL were enrolled in either group B ( telbivudine started at 28 weeks of gestation ) or group C ( control group without treatment ) . MTCT was defined as infants who were positive for serum hepatitis B surface antigen at 7 months after birth . There were 41 , 179 and 177 pregnant women ( 397 infants ) enrolled in groups A , B and C , respectively .  The HBV DNA load at 28 weeks of gestation and delivery was 1.50 ± 0.62 vs 1.45 ± 0.61 , 8.05 ± 0.37 vs 4.24 ± 0.89 and 7.94 ± 0.62 vs 7.86 ± 0.73 log10 IU/mL in groups A , B and C , respectively . The rate of MTCT in group C was 4.60 % , which was significantly higher than the rates in groups A and B ( 0 % and 0.6 % , respectively ) ( P = .043 ) . The difference between group A and group B was not significant . The rates of neonatal congenital abnormalities were 2.4 % , 0.6 % and 2.3 % in groups A , B and C , respectively , and there were no significant differences ( P = .140 ) . Telbivudine used throughout pregnancy may be safe and effective for mothers and infants , but it may not enhance the efficacy of an HBV MTCT block compared with treatment starting at 28 weeks of gestation ( NCT02253485 ) BACKGROUND In China , women with chronic HBV infection and who are of childbearing age receive lamivudine at an early age . Thus , viral resistance becomes a challenge for intervention to prevent mother-to-infant transmission . We prospect ively assessed the efficacy of tenofovir in pregnant women with lamivudine-resistant HBV . METHODS Chronic HBV-infected mothers resistant to lamivudine were enrolled . Tenofovir was administrated at gestation weeks 24 or 28 . Virological and biochemical parameters were assessed . All infants received combined immunoprophylaxis and were followed for 1 year . RESULTS Of the 48 mothers enrolled , 21 started tenofovir therapy at gestation week 24 and 27 started at week 28 . Tenofovir result ed in an HBV DNA decline of 5.23 ± 1.68 log10 IU/ml at delivery . The group starting therapy at week 24 exhibited a more rapid viral inhibition ( P<0.001 ) and more significant HBV DNA load decline ( 5.89 ± 1.66 versus 4.72 ± 1.55 ; P=0.019 ) than the group starting at week 28 . At delivery , all mothers had a viral titre < 10(6 ) IU/ml , 76.2 % from the week 24 starting group displayed virus < 10(4 ) IU/ml , and 52.4 % showed undetectable virus at delivery , much higher than the week 28 starting group ( 29.6 % ) , although there was no statistically significant difference in viral levels at delivery between the two groups . Congenital abnormalities and neonatal growth were comparable to the normal population . No case of perinatal transmission was diagnosed . CONCLUSIONS This investigation clarifies the efficacy of tenofovir for reducing vertical transmission of HBV in mothers with lamivudine-resistant HBV and demonstrates that tenofovir is well-tolerated in the second and third trimesters This study sought to assess the antiviral efficacy of lamivudine ( LMV ) administered during third trimester to reduce maternal viraemia and to identify the emergence of LMV resistance . A prospect i ve observational analysis was performed on 26 mothers with high viral load ( > 10⁷ IU/mL ) . Twenty-one women received LMV  ( treated group ) for an average of 53 days ( range 22 - 88 days ) , and the remaining five formed the untreated control group . Serum 
    Output:
    
The average HBV-DNA level before treatment was approximately 8 log10 copies/mL. Compared to the onset of antiviral intervention in the third trimester , the beginning of treatment in the second trimester distinctly reduced maternal predelivery HBV-DNA levels .
However , no significant difference in HBV MTCT was found between the second and third trimester groups .
Furthermore , the subgroup analysis showed that there were no significant differences between groups beginning treatment at different times ( second or third trimester ) with regard to HBV MTCT or other evaluated endpoints .
For pregnant women with HBV-DNA levels less than or equal to 8 log10 copies/mL , the beginning of antiviral treatment can be delayed until the third trimester