even though there have been continual advances in neonatal care and a decline in mortality of preterm infants in the past several decades , the incidence of severe long - term sequelae 

 such as chronic lung disease and neurodevelopmental disability in survivors remains high , particularly in newborns delivered at early gestational ages .
it is an important public health issue as rates of preterm birth are rising in many countries .
so , prevention and management of preterm birth continue to be a major challenge worldwide .
cervical incompetence is a known risk factor for preterm birth 

 and is considered responsible for 5% of extremely preterm deliveries ( < 28 weeks ) 

 .
the cervix plays a fundamental role in supporting a pregnancy and cervices of women with cervical incompetence show pathological dilation and shortening , leading to miscarriage or preterm birth .
different management strategies have been tried to prolong pregnancy and prevent preterm birth , including cervical cerclage .
while some studies support this technique 

 , others have failed to demonstrate benefits 

 .
infection and ensuing chorioamnionitis , bleeding and ruptured membranes are the most concerning complications associated with cervical cerclage 

 . of these complications associated with cervical incompetence
when intrauterine infection occurs , the neonate is at significant risk for respiratory distress syndrome ( rds ) , retinopathy of prematurity ( rop ) , neonatal necrotizing enterocolitis ( nec ) , bronchopulmonary dysplasia ( bpd ) , interventricular hemorrhage ( ivh ) , periventricular leukomalacia ( pvl ) , early - onset sepsis ( eos ) and even mortality 

 .
however , whether these complications caused by cervical cerclage and cervical incompetence itself could be associated with adverse neonatal outcomes remains unknown based on very little information .
the objective of the present study was to analyze whether maternal cervical incompetence with or without cerclage was associated with postnatal morbidity and mortality in preterm neonates with birth weight < 2000 g , this information may help their mothers make an informed decision about whether to undergo cervical cerclage procedure from neonatologist s perspective .
the study was approved by research ethics committee in beijing obstetrics and gynecology hospital , capital medical university ( beijing , china ) . written informed consent
we performed a retrospective cohort study reviewing all preterm neonates with birth weight less than 2000 g that were admitted to the neonatal intensive care unit or neonatal department of beijing obstetrics and gynecology hospital , capital medical university , beijing , china between january 1 , 2009 and december 31 , 2013 .
the preterm births eligible for this study were divided into two groups : neonates born to mothers with cervical incompetence and those born to mothers without cervical incompetence .
twins , multiple births , neonates with chromosome abnormalities and/or congenital malformations , and those who died in the delivery room despite adequate resuscitation , were excluded .
cervical incompetence was defined as painless dilatation and effacement of the cervix in the second trimester of pregnancy , resulting in situations of a miscarriage or a preterm birth in the absence of labor , or had sonographic evidence of cervical shortening ( cervical length < 2.5 cm measured by transvaginal ultrasound ) or funneling .
cervical cerclage either elective ( when the clinical history suggests risk of mid - trimester loss ) or emergency ( when there is evidence of a short cervix < 25 mm or cervical shortening on ultrasound ) was performed based on the attending obstetrician s judgment .
gestational age was based on mother s last menstrual period ( lmp ) or verified by early ultrasound examination if the mother s menstrual period was irregular or lmp was unknown .
as co - morbidities , rds , eos , bpd , rop , pvl , ivh ( above grade 3 ) , nec , severe asphyxia small for gestational age ( sga ) , and mortality of premature neonates were analyzed in the experimental and control groups .
nec was defined as bell 's stage ii or greater 

 and bpd was defined as oxygen dependence at 36 weeks postmenstrual age .
we categorized infants as sga if their birth weights were less than the 10th percentile for their gestational age .
rop was diagnosed by ophthalmologists according to the criteria of the international classification of retinopathy of prematurity 

 .
eos is defined as the presence of clinical signs of systemic inflammation and blood culture - proven bacterial infection of the newborn occurring in the first 3 days of life .
diagnosis of ivh was based on cranial sonograms which were performed routinely , daily in the first week of life and weekly thereafter until hospital discharge , or more frequently if clinically indicated for all preterm newborns , the definition of ivh was based on the papil grading system 

 .
severe asphyxia was defined as apgar score <3 at 1 minute or < 7 at 5 minutes 

 .
gestational diabetes mellitus ( gdm ) was diagnosed based on a 75-g 2-hour oral glucose tolerance test ( ogtt ) at pregnancy 2428 weeks according to who diagnostic criteria 

 , gdm refers to various degrees of abnormal glucose tolerance occurring or found for the first time during pregnancy .
maternal hypertension was defined as any condition including preeclampsia , eclampsia , and chronic hypertension .
clinical chorioamnionitis was defined 

 by > 2 of 6 signs : 1 ) fever > 38c , 2 ) hysteralgia , 3 ) fetal tachydardia ( > 160 beats / minute ) , 4 ) maternal tachydardia ( > 100/minute ) , 5 ) foul - smelling amniotic fluid , 6 ) increased wbc count ( 12000/mm3 ) .
prolonged rupture of membrans ( prom ) was defined as rupture of membranes lasting more than 18 hours before labor 

 .
continuous data were compared by student 's t - test , and comparisons between proportions were assessed by either the chi - square test or fisher s exact test .
a total of 581 neonates with birth weight less than 2000 g were included in the study . of these
, there were 79 cases born to mothers with cervical incompetence and 502 to mothers without cervical incompetence .
the mean gestational age among the preterm babies born to mothers with cervical incompetence was lower than control group .
infants with maternal cervical incompetence had a higher incidence of prom , maternal antibiotic therapy and clinical chorioamnionitis than in control group , while incidence of maternal hypertension was higher in the control group . in patient characteristics such as birth weight , frequency of female , vaginal delivery ,
maternal diabetes mellitus , and antenatal steroid therapy , there was no difference between the two groups .
. demographics and clinical characteristics of preterm neonates between cervical incompetence ( case ) and control groups we compared morbidity and mortality of preterm neonates ( table 2 ) and found no significant differences in the incidences of rds , rop , bpd , pvl , ivh , nec , severe asphyxia , eos , and mortality between cervical incompetence and control groups . a lower incidence of sga was detected in preterm infants in the cervical incompetence group than in control group .
postnatal morbidities of preterm neonates in the ci with cerclage ( case ) and control groups ci : cervical incompetence in 13 out of 79 mothers , mcdonald cerclage was not performed in the cervical incompetence group .
the effects of mcdonald cerclage on postnatal morbidity and mortality of preterm neonates are shown in table 3 .
there were no significant differences in the incidences of rop , bpd , pvl , ivh , nec , severe asphyxia , eos , sga , and mortality between the two groups .
postnatal morbidities between the cerclage and no cerclage in cervical incompetence groups emergency cerclage was performed in 8 out of 66 patients in the cervical incompetence group .
table 4 shows a comparison of postnatal morbidity and mortality of preterm neonates between elective - cerclage and emergency cerclage in cervical incompetence group .
incidence of rds , rop , bpd , pvl , ivh , nec , severe asphyxia , eos , sga , and mortality were not different between elective cerclage and emergency cerclage groups .
postnatal morbidities of preterm neonates in the ci with elective cerclage and emergency cerclage groups ci : cervical incompetence to analyze factors associated with frequency of rds , clinical characteristics of the cerclage and no cerclage in cervical incompetence group are presented in table 5 .
the mean weeks of gestation and mean birth weight were significantly lower in no cerclage group .
there was no significant difference in the incidence of antenatal steroid therapy between the two groups .
clinical characteristics of the cerclage and no cerclage in cervical incompetence group ci : cervical incompetence
it is increasingly being accepted that the cervix plays more than just a mechanical role , it also acts as a barrier to prevent ascending infection from the lower genital tract .
meanwhile little is known about the mortality and morbidity of preterm neonates born to mothers with cervical incompetence .
was the frequency of postnatal sequelae in preterm neonates born to mothers with cervical incompetence higher than in those born to mothers without cervical incompetence ?
in this study , we found that , except for lower frequency of sga in cervical incompetence group , there were no statistical differences in the incidences of rds , bpd , severe ivh , nec , eos , rop , pvl , severe asphyxia and mortality between the cervical incompetence and control groups .
our results agree with those of tae - jung sung 

 and disagree with the findings of mitani et al 

 which indicated that cervical incompetence was a significant factor related to the occurrence of neonatal death and abnormal cerebral ultrasound scans .
increasing evidence suggests that pathologically early cervical ripening associated with cervical incompetence was related with intrauterine infection or inflammation 

 , so we speculated that there might be higher frequency of eos of preterm neonates in cervical incompetence group , but it did not occur as expected .
we examined the clinical characteristics of neonates and found that frequency of maternal antibiotic therapy was very high in cervical incompetence group .
whether intrapartum antibiotic prophylaxis ( iap ) provided for women with cervical incompetence could alter the outcome of pregnancy and the newborn infant , is currently uncertain .
nonetheless , lee et al 

 have reported that intra amniotic inflammation was present in approximately 80% of patients with acute cervical incompetence and suggested that parenteral antibiotic treatment may sometimes reduce the intensity of the intra amniotic inflammatory response , prolonging the time interval to delivery and improving neonatal outcome .
natale et al 

 believed that antepartum group b streptococcal ( gbs ) antibiotic prophylaxis may reasonably be useful in the subset of patients with ci / bulging membranes .
so , higher frequency of maternal antibiotic therapy in our study may explain why incidence of eos of preterm neonates in cervical incompetence was not higher than in control group .
we also found that frequency of maternal hypertension was lower in cervical incompetence group which may result in lower incidence of sga in this group .
cervical cerclage is an intervention that is widely used to prevent miscarriage or delivery in the second trimester of pregnancy .
these include infection and ensuing chorioamnionitis , ruptured membranes , bleeding , miscarriage , and cervical laceration requiring repair , etc .
the effect of the procedure of cervical cerclage on the mortality and morbidity of newborns is a major concern for neonatologists . in this study , infants with no cerclage had a higher prevalence of rds compared to cerclage group ; incidence of neonatal bpd , pvl , severe ivh , nec , eos , rop , sga , severe asphyxia and mortality were not affected by cerclage status .
our results disagree with those of tae - jung sung 

 that found no significant difference in the incidences of rds in cerclage and no cerclage groups . since many risk factors are associated with frequency of rds , we analyzed clinical characteristics of preterm neonates in cerclage and no cerclage groups , and found that the neonates from mothers with no cerclage status were much smaller and younger .
this result suggests that lower gestational age and birth weight may result in higher incidence of rds in neonates with no cerclage , the lower the gestational age , the higher the risk of rds .
cervical cerclage may be performed prophylactically in the first trimester ( elective cerclage ) when the clinical history suggests risk of mid - trimester loss or as emergency at mid - trimester when there is evidence of a short cervix or cervical shortening on ultrasound .
it was reported 

 that emergency cerclage carried the highest complication rate and the outcome of these pregnancies was usually poor , so placement of emergency cerclage at mid - trimester was controversial .
andrea liddiard et al 

 recently reported that there was little difference in the gestation at delivery ( 35 vs 33 weeks ) , live birth rate ( 93% vs 92% ) and mean birth weight between the elective and emergency cerclage groups .
clinical neonatal morbidity with emergency cerclage based on limited information is not well known at present . hence , we compared the neonatal outcomes between the elective and emergency cerclage status in this study .
we found that there was no statistical difference between the two groups in the incidences of rds , bpd , severe ivh , nec , eos , rop , pvl , sga , severe asphyxia , and mortality of neonates .
this result suggests that the neonatal outcomes were not affected by emergency cerclage status in this study .
it was reported that cervical incompetence occurs in 1% of the obstetric population and up to 8% of patients with recurrent midtrimester losses 

 .
most patients and clinicians when faced with risk factors for preterm delivery seem to prefer intervention over no intervention .
cervical cerclage remains a common procedure that is offered to women at moderate to high risk .
both patients and clinicians worry about the safety of this procedure for fetus or newborns , which maybe result in no improvement in obstetrical outcomes or adverse neonatal outcomes .
overall , neonatal outcomes in the cervical incompetence group in our study are somewhat encouraging , but there are some limitations to this study . since pathology of placentas was not screened in all neonatal mothers enrolled in this study , we could not collect enough data to analyze the incidence of histopathological chorioamnionitis between cervical incompetence and control groups .
another limitations of our study were the small sample size and retrospective time frame , only 8 samples were enrolled in the emergency cerclage group and 13 samples in no cerclage group , which were still not representative of such clinical features in these preterm infants .
the results of this study provide evidence that maternal cervical incompetence , regardless of cerclage status , was not associated with postnatal adverse neonatal outcomes .
these findings can be beneficial to clinicians in the counseling and clinical management of these challenging patients .
concept / design : w. hua , z. wei , f. ling acquisition of data and data analysis : f. ling , y. song , m. jian - rong , w. ping manuscript preparation : w. hua critical revision of the manuscript : w. hua , z. wei all authors approved final version of the manuscript .
 objective : this study aimed to determine the impact of maternal cervical incompetence ( with or without mcdonald cerclage ) on mortality and morbidity of preterm infant with birth weight < 2000g.methods:581 neonates were eligible for this study , 79 with cervical incompetence and 502 without it ( control ) . 
 incidences of neonatal respiratory distress syndrome ( rds ) , bronchopulmonary dysplasia ( bpd ) , intraventricular hemorrhage ( ivh ) , neonatal necrotizing enterocolitis ( nec ) , retinopathy of prematurity ( rop ) , periventricular leukomalacia ( pvl ) , severe asphyxia , small for gestational age ( sga ) , early - onset sepsis ( eos ) , and mortality were compared between the two groups.findings:mean gestational age was earlier in cervical incompetence group than in control ( 30.22.1 vs 30.71.9 , p<0.05 ) . except lower frequency of sga 
 , there were no significant differences in the incidences of rds , bpd , rop , pvl , ivh , nec , eos , severe asphyxia and mortality between the two groups . 
 infants with no cerclage had a higher prevalence of rds ( 21/66 vs 9/13 , p<0.05 ) compared to cerclage group due to lower mean gestational age ( 30.682.1 vs 28.61.4 , p<0.01 ) and birth weight ( 1519.5274.6 vs 1205.8204.4 , p<0.001 ) , and clinical neonatal outcomes of the elective cerclage were similar to emergency cerclage in cervical incompetence groups.conclusion:maternal cervical incompetence was not associated with postnatal adverse neonatal outcomes . 
 lower mean gestational age was a major risk associated with higher prevalence of rds in preterm neonates with no mcdonald cerclage , and emergency cerclage did not predict poor clinical neonatal outcomes . 
Introduction
Subjects and Methods
Findings
Discussion
Conclusion
Authors Contribution
Conflict of Interest: