| It is one of the main causes of vaginal bleeding in the antenatal, intrapartum and postpartum, and a significant cause of maternal and perinatal morbidity and mortality. In recent years, the incidence of placenta previa has been increasing mainly because of an increasing the rate of cesarean section, artificial abortion and assisted reproductive technology. At present, with the rapid development of imaging technology, the use of ultrasound examination in pregnancy has become the main way of the diagnosis of placenta previa. Therefore, it could help to improve the placenta previa of diagnosis. One of the largest meta-analysis, which compared incidences of placenta previa in different studies around the world, showed that in studies conducted between1975and1984the overall incidence was0.37%. However, the studies conducted between1985and1995showed that the incidence increased to0.48%. Several authors have reported the relationship between race and placenta previa. The results showed that Asian women have excess risk of placenta previa compared with white women. The adjusted odds ratios ranged from1.39to2.15among Asian women by country of origin. The incidence of placenta previa was0.56%in China. Studies on the relationship between race and placenta previa have been inconsistent. Asian women have excess risk of placenta previa. The incidence of placenta previa was0.24-1.57%from domestic and0.28-1.5%from abroad. Reports about prevalence of placenta previa in our country are small samples from individual hospital or small samples, lacking multicenter and large samples analysis of a comprehensive research, which cannot fully and accurately reflect prevalence and pregnant outcome of placenta previa. We conducted a retrospective cohort study comparing all singleton pregnancies of women with and without placenta previa in seven regions of China. The aim of this study is to analyze the prevalence, risk factors and pregnant outcomes of placenta previa, in order to provide epidemiological data for the further research of placenta previa in China.[Objectives]1. To investigate the complication of pregnancy and pregnancy outcome of gravid in China.2. To investigate the prevalence of placenta previa in seven regions of China.3. To analyze the risk factors of placenta previa and high risk groups.4. To discuss maternal and neonatal outcomes associated with placenta previa and the influence of pregnancy outcomes associated with placenta previa and complication.5. To provide epidemiological data for the prevention and control of placenta previa in China.[METHODS]1. Data collectionOur survy was cross-sectional study. This is a stratified cluster random sampling study on110139pregnant women which concluded108049single pregnant women and2090multiple pregnant women in38different hospitals of seven regions in China from January2011to December2011.38different hospitals were taken from the population registration office among Northeast(Liaoning,Jilin), North China(Beijing,Hebei,Neimenggu,Shanxi), East China (Shandong,Jiangsu,Shanghai), South China(Guangzhou), Central China(Hubei), Southwest(Sichuan) and Northwest(Xinjiang,Shanxi). The case group consisted of all completed singleton pregnancies complicated by placenta previa, all other singleton pregnancies were considered controls. Control group consisted of1863simple randomly selected singleton pregnancies of women without of placenta previa in the study period. For each case,1randomly selected unmatched controls were chosen.2. Disease diagnostic criteriaPlacenta previa is a condition in which the placenta lies in the lower uterine segment, completely or partially covered the internal os of the cervix, presenting ahead of the leading pole of the fetus.The diagnosis of placenta previa was established by ultrasonography and confirmed during cesarean delivery or vaginal delivery, and the last ultrasonographic examination before delivery was used to establish correct diagnosis. Correct gestational age was derived from the first day of the last menstrual period and was checked with ultrasonographic evaluation of gestational age.3. Inclusion criteria singleton pregnancy; term (38<weeks gestational age<42weeks)4. Exclusion criteriaPregnancies with multiple pregnancies and incomplete data date were excluded from the study.5. Statistical AnalysisStatistical analysis was performed with the SPSS20.0. Measurement data description can be expressed by (mean±standard deviation), test the homogeneity of variance between the two groups, the homogeneity of variance applied a two sample t-test, heterogeneity of variance applied a t’ test; the Chi-square test or Fischer’s exact test was using for differences in qualitative variables. Multivariable logistic regression model, with forward elimination, was constructed in order to find independent risk factors. Odds ratios (OR) and their95%confidence interval (CI) were computed. P<0.05was considered statistically significant.[RESULTS]1. general situation The average age of placenta previa group was30.43±5.17. The average gestational weeks was (36.8±2.53) w. The mean of gravidity, parity and abortion were1.33±0.57,1.17±1.31and1.17±1.31in the case group. The average age of control group was28.16±4.68. The average gestational weeks was (38.79±1.89) w. The mean of gravidity, parity and abortion were1.33±0.57,1.17±1.31and0.56±0.90in the control group. There was significant difference between the two groups in the age, gestational weeks, gravidity, parity and abortion.2. incidence of placenta previa The overall incidence of placenta previa was1.2%(1304/108049) in China. The overall incidence of placenta previa was1.2%(1339/110139) in seven regions of China. The incidence of placenta previa in single and multiple were1.2%and2.6%, respectively. In terms of region, the incidence of placenta previa in different regions including northeast, north China, central China, east China, south China, southwest, northwest of China were different which was1.1%(184/16518),0.8%(287/34852),0.5%(26/5541),1.3%(280/21562),1.0%(92/8828),3.6%(350/9686),0.8%(85/11062), respectively. In terms of ages, there was clear difference among different age groups. The occurrence of placenta previa were rising with the age growing.3. The univariate analysis showed that advanced age, multipara, previous abortion, previous cesarean section and previous premature birth significantly associated with placenta previa(P<0.05).By binary Logistic analysis, we found that the risk factors of placenta previa included advanced age (25-29years,OR:1.394,P <0.05;30-34years,OR:2.008,P<0.05;≥35years,OR:2.964,P<0.05), previous abortion (≥2, OR=3.03) and previous cesarean section (OR=4.95).4. Pregnancy outcome and complications of delivery (1) method of delivery: Of the1304placenta previa of single pregnant women,1216were subjected to caesarean section(93.3%) and88to vaginal delivery(6.7%)(including84cases were natural labour and4cases were forceps delivery).(2) The rate of placental abruption was0.5%.33cases were placental abruption (2.5%) in placenta previa.(3) The rate of placenta accreta was1.1%.182cases were placenta accreta (14.4%) in placenta previa. The risk factors of placenta previa complicated with placenta increta were previous cesarean section (OR=2.121, P<0.05) and previous abortion (1, OR:1.876;>2, OR:2.536). Postpartum hemorrhage, blood transfusion and hysterectomy were most common in placenta previa complicated with placenta accreta than without placenta accreta.(4) The rate of postpartum hemorrhage was3.6%.390cases were postpartum bleeding (29.9%) in placenta previa. The inertia uteri (83.3%) is the main reason for postpartum hemorrhage.334cases accepted conservative treament and56cases accepted operative treatment.(5) Placenta accrete, postpartum hemorrhage, blood transfusion, hysterectomy and premature delivery were most common with placenta previa than without placenta previa.5. Perinatal outcomes (1)1304placenta previa single pregnant women were admitted to our hospital during2011, of whom456suffered from premature delivery (morbidity rate35.0%), and24perinatal death (1.9%).(2) Neonatal asphyxia, respiratory distress syndrome(RDS), hyperbilirubinemia and perinatal mortality were most common with placenta previa than without placenta previa. Gestational age and birth weight of newborns from mothers with placenta previa were significantly lower than control group(36.80±2.53weeks vs38.79±1.89weeks,2.95±0.63kg vs3.27±0.55kg), there was significant difference between two groups (P<0.05), and the kinds of perinatal diseases were closely correlated with the gestational age and birth weight of perinatal.(3) Neonatal asphyxia was obviously related to gestational age, birth weight, RDS(P<0.05).[CONCLUSION] 1. The overall incidence of placenta previa was1.2%(1304/108049) in China. There are some differences prevalence of placenta previa in different regions of China and in different ages. With the growth of the age, the incidence of placenta previa had an increasing trend. Pregnant women at35and above age groups are the high--risk group in placenta previa incidence.2. The risk factors were independently associated with placenta previa:advanced maternal age, previous abortion and previous cesarean section.3. Women with placenta previa were prone to placental abruption, postpartum hemorrhage, placenta increta which increased the chance of hysterectomy and blood transfusion.4. Postpartum hemorrhage, blood transfusion and hysterectomy were most common in placenta previa complicated with placenta accreta and postpartum hemorrhage than without.5. Gestational age and birth weight of newborns from mothers with placenta previa were significantly lower than control group and easily led to premature delivery, neonatal asphyxia, respiratory distress syndrome and perinatal death.6. If we can prevent the risk factors of placenta previa and diagnosis placenta previa early, the incidence of placenta previa and morbidity and mortality related to mother and fetus can be reduced.Specialty:1. This study is a large sample size and a cross-sectional survey, could accurately and objectively toreflect the real placenta previa disease clinical pathogenesis regularity.2. This study is a large sample size survey, could reflect the real placenta previa disease risk factors objectively. |
PDF Full Text Request