midwife - led primary delivery care for  low - risk  pregnant women during labor has been reported to have various advantages , such as increased odds of high maternal satisfaction and a decrease of unnecessary medical interventions [ 18 ] .
although the maternity care system for  low - risk  pregnant women peculiar to one country can not easily be compared with those in other countries , consumer demands for the  humanization  of obstetric care have arisen in various countries [ 18 ] . to date , we have found no evidence that midwife - led primary obstetric care is unsafe for  low - risk  pregnant women in comparison with obstetric care with the favorable cooperation of obstetricians and midwives in japan [ 912 ] .
in addition , about 85% of  low - risk  pregnant women request that they give birth while receiving midwife - led primary delivery care .
therefore , safe midwife - led delivery care with the backup of obstetricians may also be required for  low - risk  pregnant women in japan . if complications occur or threaten to occur during the primary midwife - led delivery care , the midwives have to refer the woman to obstetricians at the same or a neighboring hospital or private obstetric clinic as soon as possible .
this is because , in deliveries managed by independent midwives in japan , many intervention measures , such as oxytocin infusion , epidural anesthesia , episiotomy , suture , and instrumental delivery , are not available based on japanese legal restrictions . in our institute , one of the main tokyo city perinatal centers , there are 3 japanese systems of midwife - led delivery care , as follows : ( 1 ) those intending to give birth at home managed by midwives who do not belong to our hospital , ( 2 ) those planning to give birth on  futons 
( i.e. , japanese - style bedding ) in japanese tatami mat delivery rooms in our hospital managed by the same midwives who do not belong to our hospital , and ( 3 ) those planning to give birth in japanese tatami mat delivery rooms managed by midwives who belong to our hospital .
the objective of this study was to describe trends in transfers and perinatal outcomes among labors using these 3 japanese systems of midwife - led primary delivery care .
the protocol for this analysis was approved by the ethics committee of the japanese red cross katsushika maternity hospital . in addition ,
informed consent for analysis from a retrospective database was obtained from each subject during their hospital visit . in our hospital ,
pregnant women who are initially considered  low - risk  at 3436 weeks of gestation can choose freely between the 3 systems of midwife - led care and obstetric shared care .
in the midwife - led care units , midwives can practice autonomously and are fully accountable for their own practice , unsupervised by obstetricians .
factors used to exclude women from the  low - risk  group comprise the following [ 912 ] : ( 1 ) medical history : pregnancy - induced hypertension , chronic hypertension , diabetes mellitus , renal disease , idiopathic thrombocytopenia , and other systemic illnesses ; ( 2 ) gynecological history : history of infertility therapies of in vitro fertilization , congenital uterine anomalies , uterine myomatosis , and adnexal anomaly ; ( 3 ) obstetric history : narrowing of the pelvic outlet , cephalopelvic disproportion , previous cesarean section , previous anal sphincter injury , previous postpartum hemorrhage  1,000  ml with blood transfusion , previous manual removal of placenta , previous gestational diabetes , and history of severe preeclampsia ; ( 4 ) complications during the present pregnancy : multiple pregnancy , nonvertex presentation , obesity ( maternal body mass index before pregnancy  25 and/or during the third trimester  28 ) , anemia ( hemoglobin < 9.0  g / dl ) , epilepsy with treatment , polyhydramnios , oligohydramnios , low - set placenta , placenta previa , fetal growth restriction , heavy for date fetus , gestational diabetes , and pregnancy - induced hypertension ; when risk factors are present , those women are managed by obstetricians and midwives ; ( 5 ) complications during labor : intrauterine infection , thick meconium staining , prolongation of labor such as active - phase dilation < 1  cm / hour and duration of second stage of labor  2 hours , prolonged rupture of membranes ( 24 hours ) , uterine inertia , arrest of labor , and fetal heart rate abnormality such as a nonreassuring fetal status . when these factors are present , the women are transferred to be managed mainly by obstetricians ( obstetric shared care ) in a standard western - style delivery room or surgery room in our hospital .
a retrospective study was performed to examine trends in transfers and perinatal outcomes among labors that started using the 3 systems of midwife - led primary delivery care . in this study ,
student 's t - test was used for continuous variables and the  test for categorical variables .
odds ratios ( ors ) and 95% confidence intervals ( cis ) were also calculated . differences with p
between 2009 and 2012 , a total of 678 low - risk women were placed in the 3 forms of midwife - led primary delivery care at the onset of labor pains and/or rupture of membranes at 3741 weeks of gestation . of these ,
123 ( 18% ) intended to give birth at home , 88 ( 13% ) planned to give birth in the japanese tatami mat rooms in our hospital managed by midwives who do not belong to our hospital , and 467 ( 59% ) planned to give birth managed by the midwives belonging to our hospital . 

table 1 shows the clinical descriptions of the 678 pregnant women initially considered as  low - risk  for receiving our midwife - led primary delivery care systems . there were no significant differences in the maternal age or parity among the 3 groups . 

table 2 shows the rate of transfers in the 3 groups of the midwife - led primary delivery care systems .
the total rate of transfers in the system run by the midwives belonging to our hospital ( 56% ) was higher than in the other 2 systems run by the independent midwives ( 31% in planned home birth : or 1.87 , 95% ci 1.23.0 , p < 0.01 ; 38% in planned hospital birth : or 2.51 , 95% ci 1.73.8 , p < 0.01 ) .
in addition , the timing of transfers in the system run by the midwives belonging to our hospital ( before the second stage of labor : 52% ) was earlier than those in the other 2 systems ( 21% in the planned home birth : or 4.12 , 95% ci 2.66.6 , p < 0.01 ; 20% in planned hospital birth : or 4.29 , 95% ci 2.57.4 , p < 0.01 ) . however , if classified into nulliparous and parous women , there were no significant differences in the rate of transfers among the 3 groups , as shown in table 1 .
in addition , among the 3 groups there were no significant differences in the rate of the main 2 indications for transfer : fetal heart rate abnormality and failure to progress .
the main indications for transfer after delivery were maternal postpartum hemorrhage and neonatal respiratory distress associated with asphyxia . 

table 3 shows the obstetric and neonatal outcomes in the pregnant women initially considered as  low - risk  for receiving our midwife - led primary delivery care systems . there were no significant differences in these outcomes among the 3 groups
our obstetric care system involves the division of women in labor into low- and high - risk groups [ 912 ] .
the women who are initially considered low - risk can choose freely between midwife - led care and obstetric shared care . if complications occur or risk factors arise during labor in the primary midwife - led care , they are transferred to obstetric shared care .
this may be the first report concerning the differences in the timing of transfers from midwife - led care to obstetric shared care among the 3 systems of midwife - led primary delivery care in japan . in this study
, there was no evidence that the primary midwife - led care is unsafe for  low - risk  pregnant women in any of these 3 midwife - led delivery care systems .
however , there were no significant differences in the timing of referrals from midwife - led care to obstetric shared care between the system led by midwives who belong to our hospital ( hospital midwifery system ) and the systems led by the midwives who do not belong to our hospital . in the hospital midwifery system
, the timing of transfers seemed to be the earliest due to the ease of transfer within the same hospital and administrator setting . on the other hand ,
the rate of transfers after delivery with the other 2 systems was higher than that in the hospital midwifery care . during the period , the main indications for transfers were maternal postpartum hemorrhage and/or neonatal respiratory distress associated with asphyxia .
fortunately , the difference was not associated with adverse obstetric or neonatal outcomes ; however , unfortunately , they led to early mother - to - child separation , especially in cases of planned home birth because healthy puerperal women or newborns can not be transferred from home to hospital according to japanese law .
although home birth might be very comfortable , those involved must be prepared for mother - to - child separation in cases of referrals after delivery .
the major limitations of this study were the small sample size and lack of long - term follow - up of mothers and children to consider the potential of the findings based on our own context .
there were no cases of fetal / neonatal death under the midwife - led delivery care .
the most evaluated outcome under midwife - led delivery was the satisfaction of pregnant women with the development of mother - child relationships after delivery .
in addition , there might be some bias related to the backgrounds in the selection of the systems because this was not a randomized trial study .
therefore , a further large prospective study with long - term follow - up may be needed .
there were no significant differences in perinatal outcomes among the 3 systems ; however , there were some differences in the status of the transfers to the obstetric shared care .
 
 objective . 
 the objective of this study was to describe the recent clinical characteristics of labor using 3 systems of japanese midwife - led primary delivery care , as follows : ( 1 ) those intending to give birth at home managed by midwives who do not belong to our hospital , ( 2 ) those planning to give birth in our hospital managed by the same midwives , and ( 3 ) those planning to give birth managed by midwives who belong to our hospital . 
 methods . a retrospective cohort study was performed . 
 results . 
 there were no significant differences in the obstetric or neonatal outcomes among the 3 groups . 
 the rate of transfers during labor with the system involving midwives belonging to our hospital was higher than those with the other 2 systems . 
 in addition , the timing of transfers in the system with the midwives belonging to our hospital was earlier than with the other 2 systems . among the 3 groups , 
 there were no significant differences in the rate of the main 2 indications for transfers : fetal heart rate abnormality and failure to progress . conclusion . 
 there were no significant differences in perinatal outcomes among the 3 systems ; however , there were some differences in the status of transfers to obstetric shared care . 
1. Introduction
2. Methods
3. Results
4. Discussion
5. Conclusion