***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: Between 1983 and 1984 a double-blind r and omized study with progesterone substitution in threatened abortion was carried out . Fifty-six patients with vaginal bleeding during the first trimester of pregnancy , the internal cervical os being closed , were referred to the hospital . Twenty-five women ( 5th and 6th week of gestation ) with positive serum concentrations of beta-hCG were admitted to the study without regard to sonogram results . In other 25 women ( 7th-10th week of pregnancy ) and 6 women ( greater than or equal to 11th week of pregnancy )  fetal heart action and movement could be demonstrated by ultrasound . The patients were prescribed bed rest and vaginal suppositories twice daily , containing either 25 mg progesterone or only polyethylene glycol . The code was not broken until after completion of the study . Serial serum determinations of beta-hCG , estradiol-17 beta ( E2 ) , progesterone , and ultrasound  were performed . Four patients had to be omitted from final analysis ( two tubal pregnancies , one intrauterine infection , one sectio parva ) . Three of 26 patients progesterone ( 11 % ) and five of 26 patients with placebo ( 19 % ) had an abortion , which represented no significant difference . Frequency of abortion was increased in women more than 30 years old , in women with previous abortions and after ovulation induction . Progesterone treatment result ed in a significant elevation of serum progesterone concentrations ( p less than 0.01 ) , while beta-hCG and E2 were unchanged . The results of this study confirm that pregnancy outcome is favorable in women with bleeding and normal hormone concentrations without hormonal treatment and unfavorable in women with reduced beta-hCG and E2-concentrations . ( ABSTRACT TRUNCATED AT 250 WORDS BACKGROUND Midtrimester amniocentesis to investigate fetal karyotype carries a small risk of fetal loss . AIM To test the hypothesis that progesterone prophylaxis may reduce this . STUDY DESIGN A r and omised controlled trial comparing a short prophylactic treatment with progesterone after amniocentesis with untreated controls . RESULTS There were no differences in frequency of miscarriage , preterm delivery or neonatal outcome . CONCLUSION Prophylactic progesterone treatment after amniocentesis does not improve obstetric outcome Presented herein is a r and omized prospect i ve study performed to evaluate the efficacy of the addition of lymphocyte immunotherapy ( LI ) to progesterone ( P ) therapy ( LI/P ) for the prevention of spontaneous abortion ( SAB ) in primary aborters with a history of three SABs . The incidence of intrauterine pregnancies in four cycles was 23 of 35 ( 65.7 % ) patients for LI/P vs. 14 of 31 ( 45.1 % ) patients treated with progesterone alone .  SABs occurred in 6 of 23 ( 26.0 % ) LI/P-treated patients compared to 8 of 14 ( 57.1 % ) given progesterone alone . The mean number of previous abortions in both groups was 3.9 . The  mean age of the LI/P group was 34.1 vs. 33.6 years for the group treated with progesterone alone . These data could be interpreted to show that progesterone therapy and LI independently inhibit SAB or that LI/P acts synergistically to inhibit immune destruction .  LI/P therapy was found to be more effective than progesterone therapy alone Statement of Retraction We , the Editors and Publisher of The Journal of Maternal-Fetal & Neonatal Medicine , have retracted the following article : Alaa M. Ismail , Ahmed M. Abbas , Mohammed K. Ali & Ahmed F. Amin ; Peri-conceptional progesterone treatment in women with unexplained recurrent miscarriage :  a r and omized double-blind placebo-controlled trial , The Journal of Maternal-Fetal & Neonatal Medicine , http://10.1080/14767058.2017.1286315 While this article was peer- review ed and accepted according to the Journal ’s policy concerns were subsequently raised regarding the accuracy and reliability of the data . The Editors-in-Chief were made aware of previous versions of the article which showed significant changes to the underlying data . After an investigation the authors of the paper were contacted but were unable to provide the original data to verify their results . The authors have been informed about the retraction . We have been informed in our decision-making by our policy on publishing ethics and integrity and the COPE guidelines on retractions . The retracted article will remain online to maintain the scholarly record , but it will be digitally watermarked on each page as “ Retracted ” BACKGROUND Progesterone is essential for the maintenance of pregnancy . However , whether progesterone supplementation in the first trimester of pregnancy would increase the rate of live births among women with a history of unexplained recurrent miscarriages is uncertain . METHODS We conducted a multicenter , double-blind , placebo-controlled , r and omized trial to investigate whether treatment with progesterone would increase the rates of live births and newborn survival among women with unexplained recurrent miscarriage . We r and omly assigned women with recurrent miscarriages to receive twice-daily vaginal suppositories containing either 400 mg of micronized progesterone or matched placebo from a time soon after a positive urinary pregnancy test ( and no later than 6 weeks of gestation ) through 12 weeks of gestation . The primary outcome was live birth after 24 weeks of gestation . RESULTS A total of 1568 women were assessed for eligibility , and 836 of these women who conceived naturally within 1 year and remained willing to participate in the trial were r and omly assigned to receive either progesterone ( 404 women ) or placebo ( 432 women ) . The follow-up rate for the primary outcome was 98.8 % ( 826 of 836 women ) . In an intention-to-treat analysis , the rate of live births was 65.8 % ( 262 of 398 women ) in the progesterone group and 63.3 % ( 271 of 428 women ) in the placebo group ( relative rate , 1.04 ; 95 % confidence interval [ CI ] , 0.94 to 1.15 ; rate difference , 2.5 percentage points ; 95 % CI , -4.0 to 9.0 ) . There were no significant between-group differences in the rate of adverse events . CONCLUSIONS Progesterone therapy in the first trimester of pregnancy did not result in a significantly higher rate of live births among women with a history of unexplained recurrent miscarriages . ( Funded by the United Kingdom National Institute of Health Research ; PROMISE Current Controlled Trials number , IS RCT N92644181 . ) The CONSORT ( Consoli date d St and ards of Reporting Trials ) statement is used worldwide to improve the reporting of r and omized , controlled trials . Schulz and colleagues describe the latest version , CONSORT 2010 , which up date s the reporting guideline based on new method ological evidence and accumulating experience . OBJECTIVE --To investigate the incidence of spontaneous abortion in a population of women in order to establish their risk of spontaneous abortion and the obstetric factors predisposing to it . DESIGN -- Prospect i ve study of women recruited by radio and poster appeal and from hospital outpatient clinics . SETTING --English provincial community . PATIENTS --630 Women from the general population intending to become pregnant . INTERVENTIONS --The viability of the pregnancy was assessed by  abdominal ultrasonography  before completion of the eighth week , and the assessment was repeated if vaginal bleeding occurred . MAIN OUTCOME MEASURE -- Spontaneous abortion or live births in women with or without a previous history of spontaneous abortion . RESULTS --The overall incidence of clinical ly recognisable spontaneous abortion before 20 weeks of gestation was 12 % ( 50/407 pregnancies ) . The risk of spontaneous abortion in each category of patient was classified with respect to the patient 's past reproductive performance and found to be influenced greatly by her previous obstetric history . In primigravidas and women with a history of consistently successful pregnancies the incidences of abortion were low ( 5 % ( 4/87 ) and 4 % ( 3/73 ) respectively ) , whereas women with only unsuccessful histories had a much greater risk of aborting the study pregnancy ( 24 % ( 24/98 ) ) , even when their sole pregnancy had ended in abortion ( 20 % ( 12/59 ) ) . The outcome of the last pregnancy also influenced the outcome of the study pregnancy ; only 5 % of women ( 5/95 ) whose previous pregnancy had been successful aborted , whereas the incidence of loss of pregnancy among women whose last pregnancy had aborted was 19 % ( 40/214 ) . CONCLUSIONS --A knowledge of the patient 's reproductive history is essential for the clinical assessment of her risk of spontaneous abortion . As the most important predictive factor for spontaneous abortion is a previous abortion , the outcome of a woman 's first pregnancy has profound consequences for all subsequent pregnancies BACKGROUND The aim was to study whether prolongation of luteal support during early pregnancy influences the delivery rate after IVF . METHODS Dual centre study including 303 women who achieved pregnancy after IVF or ICSI was used . All were treated with the long protocol using GnRH agonists and given luteal support with 200 mg vaginal progesterone three times daily during 14 days from the day of transfer until the day of a positive HCG test . The study group ( n = 150 ) withdrew vaginal progesterone from the day of positive HCG . The control group ( n = 153 ) continued administration of vaginal progesterone during the next 3 weeks of pregnancy . RESULTS The number of miscarriages prior to and after week 7 of gestation was seven ( 4.6 % ) and 15 ( 10.0 % ) in the study group and five ( 3.3 % ) and 13 ( 8.5 % ) in the control group respectively . The number of deliveries was 118 ( 78.7 % ) in the study group and 126 ( 82.4 % ) in the control group . The differences were not significant . CONCLUSIONS Prolongation of progesterone supplementation in early pregnancy has no influence on the miscarriage rate , and thus no effect on the delivery rate .  Progesterone supplementation can safely be withdrawn at the time of a positive HCG test Deficiency in the luteal phase has been shown during stimulated cycles using a protocol involving a GnRH agonist . The authors undertook a r and omised prospect i ve trial of supplementation by progesterone of the luteal phase and of early pregnancy in two hundred and seventy two patients requiring fertilisation in vitro ( FIV ) , gamete inter-fallopian transfer ( GIFT ) or zygote inter-fallopian transfer ( ZIFT ) .  Either progesterone in solution in oil ( 50 mg/day ) administered by intramuscular injection or micronized progesterone administered intra-vaginally ( 600 mg/d ) were used as support for the luteal phase . Administration of progesterone in association with estradiol valerate was started on the day prior to oocyte puncture and was continued until the 12th week of pregnancy . The implantation rate was very close to the threshold of significance ( P = 0.07 ) in favour of the patients given vaginal progesterone . There was a higher rate of clinical pregnancies ( 33.6 versus 26.7 p. cent ) in the latter group , though this was not significant . While plasma progesterone ( Pg ) levels were lower in patients using vaginal progesterone , the abortion rate during the first three months was lower in this group ( P < 0.05 ) . Micronized progesterone administered vaginally was well tolerated by all patients . During stimulated cycles , notably by GnRHa , it thus proved to be more effective than Pg administered by intramuscular injection with regard to implantation and abortion rates BACKGROUND The aim of this study was to assess whether the cessation of progesterone ( P ) supplementation during early pregnancy after GnRH antagonist cycles is not inferior to its continuation in terms of pregnancy rates beyond 12 weeks of gestation METHODS There were 200 patients , with a positive β-hCG test ( followed by a doubling in β-hCG levels 48 h later ) after a fixed recombinant FSH (recFSH)/GnRH antagonist protocol for IVF/ICSI and a Day-3 fresh embryo transfer ( ET ) , participated in this r and omized controlled study . All patients received luteal support  , with 200 mg vaginal P being administered three times daily for 14 days , beginning on the day of ET until the second β-hCG test , 16 days post-ET . In the control group ( n = 100 ) the administration of P was continued until 7 weeks of gestation . In the study group ( n = 100 ) , vaginal P was discontinued on the 16th day post-ET  RESULTS : The ongoing pregnancy rate beyond 12 weeks , the primary outcome measure , did not differ between the study and control groups ( 82 versus 73 % , P = 0.175 ; difference 9 % , 95 % CI : 
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No clear differences were seen for women receiving progestogen for the other secondary outcomes including neonatal death , fetal genital abnormalities or stillbirth .
There may be little or no difference in the rate of low birthweight and trials did not report on the secondary child outcomes of teratogenic effects or admission to a special care unit .
AUTHORS ' CONCLUSIONS For women with unexplained recurrent miscarriages , supplementation with progestogen therapy may reduce the rate of miscarriage in subsequent pregnancies