***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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    Input: 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 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 Summary . The clinical and endocrine effects of progestogen therapy in early pregnancy were investigated using a double‐blind r and omized trial in 64 patients who had a viable fetus at 6 weeks gestation and had an increased risk of miscarriage . The patients were r and omly allocated to receive either 17 alpha‐hydroxyprogesterone caproate or a placebo between 7 and 12 weeks gestation . Four fetal ultrasonographic variables and 17 maternal endocrine variables were studied in each woman . Only four maternal serum variables ( 17 alpha‐hydroxyprogesterone , prolactin , thyroxin and thyroxin binding globulin ) rose significantly . The serum progesterone levels in the hormone supplemented group were on average 20 % higher than in the placebo group but the difference was not statistically significant . However , the relation between the progesterone levels and the fetal outcome was not clear . Therefore it is not advisable to prescribe 17‐OHP‐C during early pregnancy to prevent a miscarriage Abstract Objective : To determine whether prepregnancy pituitary suppression of luteinising hormone secretion with a luteinising hormone releasing hormone analogue improves the outcome of pregnancy in ovulatory women with a history of recurrent miscarriage , polycystic ovaries , and hypersecretion of luteinising hormone . Design : R and omised controlled trial . Setting : Specialist recurrent miscarriage clinic . Subjects : 106 women with a history of three or more consecutive first trimester miscarriages , polycystic ovaries , and hypersecretion of luteinising hormone . Interventions : Women were r and omised before conception to receive pituitary suppression with a luteinising hormone releasing hormone analogue followed by low dose ovulation induction and luteal phase progesterone ( group 1 ) or were allowed to ovulate spontaneously and then given luteal phase progesterone alone or luteal phase placebo alone ( group 2 ) . No drugs were prescribed in pregnancy . Main outcome measures : Conception and live birth rates over six cycles . Results : Conception rates in the pituitary suppression and luteal phase support groups were 80 % ( 40/50 women ) and 82 % ( 46/56 ) respectively ( NS ) . Live birth rates were 65 % ( 26/40 ) and 76 % ( 35/46 ) respectively ( NS ) . In the luteal phase support group there was no difference in the outcome of pregnancy between women given progesterone and those given placebo pessaries . Live birth rates from an intention to treat analysis were 52 % ( 26/50 pregnancies ) in the group given pituitary suppression and 63 % ( 35/56 ) in the controls ( NS ) . Conclusions : Prepregnancy suppression of high luteinising hormone concentrations in ovulatory women with recurrent miscarriage and hypersecretion of luteinising hormone does not improve the outcome of pregnancy . The outcome of pregnancy without pituitary suppression is excellent . Key messages Hypersecretion of luteinising hormone seems not to be causally related to early pregnancy loss Further research should be directed at other endocrine factors controlling implantation Excellent live birth rates can be achieved with supportive care alone in a specialised The effect of medroxyprogesterone acetate upon the duration and char acteristics of human gestation and labor  was studied . 200 pregnant women ( 36 - 38 weeks gestation ) were r and omly assigned to a group receiving 20 mg 4 times/day or to a group receiving only the tablet base . This double-blind study failed to reveal any effect upon the duration of pregnancy or the characteristics of pregnancy labor or fetal conditions 
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REVIEW ER 'S CONCLUSIONS There is no evidence to support the routine use of progestogen to prevent miscarriage in early to mid pregnancy .
However , further trials in women with a history of recurrent miscarriage may be warranted , given the trend for improved live birth rates in these women and the finding of no statistically significant difference between treatment and control groups in rates of adverse effects suffered by either mother or baby in the available evidence