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1.
Ectopic pregnancy and prior induced abortion.   总被引:4,自引:3,他引:1       下载免费PDF全文
We compared the prior pregnancy histories of 85 multigravid women with an ectopic pregnancy and 498 multigravid delivery comparison subjects. We found a relationship between the number of prior induced abortions and the risk of ectopic pregnancy: the crude relative risk of ectopic pregnancy was 1.6 for women with one prior induced abortion and 4.0 for women with two or more prior induced abortions; however, use of multivariate techniques to control confounding factors reduced the relative risks to 1.3 (95 per cent confidence interval, 0.6-2.7) and 2.6 (95 per cent confidence interval, 0.9-7.4), respectively. The analysis suggests that induced abortion may be one of several risk factors for ectopic pregnancy, particularly for women who have had abortions plus pelvic inflammatory disease or multiple abortions.  相似文献   

2.
BACKGROUND. Most studies report that a single induced abortion does not increase risk for delivering a low birth weight infant in a subsequent pregnancy. However, the effect of multiple abortions has not been adequately evaluated. METHODS. This relationship was studied in 6541 White women who delivered their first child between 1984 and 1987. We compared the frequencies of low birth weight (less than 2500 g) among infants born to 1999 women without prior induced abortion and 1999 women with one abortion with the frequencies of low birth weight among infants born to women with two (n = 1850), three (n = 520), and four or more (n = 173) prior induced abortions. RESULTS. After adjustment for confounding variables, we found no linear relationship in risk of low birth weight among women with one (relative risk [RR] = 1.2, 95% confidence interval [CI] = 0.9-1.5), two (RR = 1.5, 95% CI = 1.1-2.0), three (RR = 1.3, 95% CI = 0.8-1.9), or four or more (RR = 1.6, 95% CI = 0.9-2.9) prior induced abortions. CONCLUSIONS. These findings confirm earlier reports of little or no evidence of harmful effects on birth weight by one or by two or more induced abortions. We further report that risk is not significantly elevated even in women with three, four, or more prior terminations of pregnancy when compared with women with one or two abortions.  相似文献   

3.
Induced abortion and the risk of subsequent ectopic pregnancy.   总被引:2,自引:2,他引:0       下载免费PDF全文
This study assessed the effect of legal induced abortion on ectopic pregnancy risk by using a comparison group of reproductive-age women who were at risk of becoming pregnant during the same time period the women with ectopic pregnancy conceived. Cases were members of Group Health Cooperative of Puget Sound who were hospitalized for ectopic pregnancy from October 1981 through September 1986 (N = 211). Controls were randomly selected members matched to cases on age and county of residence (N = 457). All subjects in this analysis had had one or more prior pregnancies. Eighty-eight cases (41.7 per cent) and 177 controls (38.7 per cent) had a history of one or more induced abortions. The relative risk of ectopic pregnancy associated with one abortion was 0.9 (95 per cent confidence interval 0.6, 1.3), adjusted for age, county, reference date, religion, gravidity, age at first pregnancy, lifetime number of sexual partners, and miscarriage history. Among women with two or more prior pregnancies, the risk associated with two or more abortions was 1.2 (0.6, 2.4). Controlling for pelvic inflammatory disease and use of intrauterine devices did not alter these risks. We conclude that legal abortion as performed in the US since 1970 has little or no influence on a woman's risk of ectopic pregnancy in subsequent pregnancies.  相似文献   

4.
This case-control study was associated with a regional register of ectopic pregnancy between 1993 and 2000 in France. It included 803 cases of ectopic pregnancy and 1,683 deliveries and was powerful enough to investigate all ectopic pregnancy risk factors. The main risk factors were infectious history (adjusted attributable risk = 0.33; adjusted odds ratio for previous pelvic infectious disease = 3.4, 95% percent confidence interval (CI): 2.4, 5.0) and smoking (adjusted attributable risk = 0.35; adjusted odds ratio = 3.9, 95% CI: 2.6, 5.9 for >20 cigarettes/day vs. women who had never smoked). The other risk factors were age (associated per se with a risk of ectopic pregnancy), prior spontaneous abortions, history of infertility, and previous use of an intrauterine device. Prior medical induced abortion was associated with a risk of ectopic pregnancy (adjusted odds ratio = 2.8, 95% CI: 1.1, 7.2); no such association was observed for surgical abortion (adjusted odds ratio = 1.1, 95% CI: 0.8, 1.6). The total attributable risk of all the factors investigated was 0.76. As close associations were found between ectopic pregnancy and infertility and between ectopic pregnancy and spontaneous abortion, further research into ectopic pregnancy should focus on risk factors common to these conditions. In terms of public health, increasing awareness of the effects of smoking may be useful for ectopic pregnancy prevention.  相似文献   

5.
Ectopic pregnancy and prior induced abortion   总被引:1,自引:0,他引:1  
As part of the Women's Health Study, a case-control study conducted in nine cities in the United States, women hospitalized with an ectopic pregnancy and women hospitalized with non-gynecologic, medical or surgical diagnoses were interviewed concerning past reproductive history. There were 462 women meeting eligibility criteria in the ectopic pregnancy case group and 2326 women meeting the criteria for the control group. After adjustment for a number of possible confounders, the relative risk of ectopic pregnancy for women with a history of one induced abortion was 1.0 (95% confidence limits: 0.5 to 1.8) and was 0.9 (95% confidence limits: 0.8 to 1.1) for women with a history of two or more prior induced abortions. These results suggest that prior induced abortion does not significantly increase the risk of subsequent ectopic pregnancy.  相似文献   

6.
A case-control (n = 1427 and 3001, respectively) study in Connecticut found no relationship between delivery of an infant with congenital malformations and overall previous experience of induced abortion (odds ratio (o) = 0.9, 95% CL = 0.7, 1.1). Delivery of a congenitally malformed infant was also unrelated to: 1)abortion of penultimate pregnancy, 2) abortion of first pregnancy when index pregnancy is second, and 3) multiple previous abortions. Non-white women aged 25-29 who delivered a malformed child were significantly more likely to have aborted ( o = 2.6,95% CL = 1.2, 5.8, p less than 0.05). This may be due to more frequent histories of illegal and septic abortion, or to other characteristics of these women. Legal abortion performed under safe clinical conditions appears to impose no increased risk for subsequent delivery of a malformed infant.  相似文献   

7.
PURPOSE: Low birth weight (LBW), preterm births, abnormal placentation, and miscarriages have been associated with prior induced abortions. An incidence-related effect has been suggested. The objective of this study is to assess the effects of prior induced abortions on obstetric risk factors and pregnancy outcome in conditions of free high-standard maternity care used by almost the entire pregnant population in Finland. METHODS: We analyzed a population-based database including 26,976 singleton pregnancies from 1989 to 2001, of which 2364 were among women with one prior induced abortion and 355 women had had at least two prior induced abortions. Data included maternal risk factors, pregnancy characteristics, and obstetric outcome measures and were based on results of a self-administered questionnaire at 20 weeks of pregnancy and clinical records. Odds ratios (ORs) concerning pregnancy outcomes were calculated in multiple logistic regression analysis. RESULTS: Induced abortions were associated with several known pregnancy risk factors; specifically, maternal age older than 35 years, unemployment, unmarried status, low educational level, smoking, alcohol consumption, overweight condition, and chronic illnesses. Preterm birth (OR, 1.19; 95% confidence interval, 1.01-1.41) in women with one prior abortion (7.3% versus 6.2%) and LBW (OR, 1.54; 95% confidence interval, 1.02-2.32) in women with two or more prior abortions (7.0% versus 4.7%) appeared to be more common, but after logistic regression analysis, we found no evidence of adverse pregnancy outcomes. CONCLUSIONS: Induced abortion is not an independent risk factor for adverse obstetric outcome. Marked health behavioral pregnancy risks are associated with prior induced abortions. Health counseling of these women is a challenge, but this objective has not yet been achieved.  相似文献   

8.
We examined the effect of abortion type, number, and gestational age on the risk of preeclampsia and transient hypertension among women who received prenatal care from 13 obstetric practices in southern Connecticut between April 1988 and December 1991 (N = 2,739). Subjects were interviewed before 16 weeks' gestation regarding reproductive history and pregnancy-related risk factors. We estimated the risk of preeclampsia (N = 44) and transient hypertension (N = 172) among nulliparous women who had had one or more abortions, with nulliparous women with no abortion as the referent group. Similar effects were seen for one spontaneous or induced abortion, when analyzed separately. A single prior abortion was associated with a decreased risk of preeclampsia [odds ratio (OR) = 0.35; 95% exact confidence interval (CI) = 0.09-1.01]. One abortion had only a small association with risk of transient hypertension (OR = 1.09, 95% exact CI = 0.68-1.72); however, a history of two or more abortions was associated with a decreased risk (OR = 0.42, 95% exact CI = 0.16-0.94). Among nulliparous women with a history of one abortion, a decreased risk of both hypertensive disorders was observed among women whose aborted pregnancy ended at > or =3 months gestation. These findings suggest that a history of abortion in nulliparous women is a protective factor against the risk of preeclampsia in the subsequent pregnancy.  相似文献   

9.
STUDY OBJECTIVE--The aim was to determine whether induced abortions could increase the risk of secondary infertility. DESIGN--This was a case-control study; cases were women with secondary infertility, individually matched to two controls who were currently pregnant. Each participant was interviewed by one of two medical doctors using a questionnaire that sought information on their demographic, socioeconomic, medical, and reproductive status. The data were analysed by conditional logistic regression. SETTING--The study took place in the Alexandra Maternity Hospital in Athens, Greece, in 1987-88. PARTICIPANTS--84 women consecutively admitted with secondary infertility and 168 pregnant controls took part. MAIN RESULTS--Eight cases and no controls reported a previous ectopic pregnancy, confirming that the occurrence of a pregnancy of this type dramatically increases the risk of secondary infertility. Furthermore, the occurrence of either induced abortions or spontaneous abortions independently and significantly increased the risk of subsequent development of secondary infertility. The logistic regression adjusted relative risks (and 95% confidence intervals) for secondary infertility were 2.1 (1.1-4.0) when there was one previous induced abortion and 2.3 (1.0-5.3) when there were two previous induced abortions. Tobacco smoking significantly increased the risk of secondary infertility, the adjusted relative risk being 3.0 (1.3-6.8). CONCLUSIONS--Legalised induced abortions, as currently practised in Greece, appear to increase slightly the relative risk of secondary infertility.  相似文献   

10.
Child-bearing after induced abortion: reassessment of risk.   总被引:2,自引:0,他引:2  
We reviewed 1791 singleton pregnancies of women with a history of previous induced abortion and compared them with 14,857 pregnancies in mothers with no previous induced abortions. Therapeutic termination of pregnancy was associated with a statistically significant increase in the incidence of low birth weight infants and bleeding in the first trimester of pregnancy. When other variables were examined, no significant differences were found between the two groups, except for a significantly higher rate of stillbirths among women who had not had a prior induced abortion. There were no increases in major or minor congenital malformations.  相似文献   

11.
BACKGROUND: To examine whether induced abortion increases the risk of low birthweight in subsequent singleton live births. METHODS: Cohort study using the Danish Medical Birth Registry (MBR), the Hospital Discharge Registry (HDR), and the Induced Abortion Registry (IAR). All women who had their first pregnancy during 1980-1982 were identified in the MBR, the HDR, and the IAR. We included all 15,727 women whose pregnancy was terminated by a first trimester induced abortion in the induced abortion cohort and 46,026 women whose pregnancy was not terminated by an induced abortion were selected for the control cohort. All subsequent pregnancies until 1994 were identified by register record linkage. RESULTS: Low birthweight (<2500 g) in singleton term live births occurred more frequently in women with one, two, three or more previous induced abortions, compared with women without any previous induced abortion of similar gravidity, 2.2% versus 1.5%, 2.4% versus 1.7%, and 1.8% versus 1.6%, respectively. Adjusting for maternal age and residence at time of pregnancy, interpregnancy interval, gender of newborn, number of previous spontaneous abortions and number of previous low birthweight infants (control cohort only), the odds ratios (OR) of low birthweight in singleton term live births in women with one, two or more previous first trimester induced abortions were 1.9 (95% CI: 1.6, 2.3), and 1.9 (95% CI: 1.3, 2.7), respectively, compared with the control cohort of similar gravidity. High risks were mainly seen in women with an interpregnancy interval of more than 6 months. CONCLUSIONS: The findings suggest a positive association between one or more first trimester induced abortions and the risk of low birthweight in subsequent singleton term live births when the interpregnancy interval is longer than 6 months. This result was unexpected and confounding cannot be ruled out.  相似文献   

12.
BACKGROUND: There is inconsistent evidence as to whether work schedule (including rotating shifts and night work) can affect reproductive outcomes. METHODS: We investigated the association between work schedule and risk of spontaneous abortion in U.S. nurses. The Nurses' Health Study II is a prospective cohort study established in 1989. In 2001, information about occupational activities and exposures during pregnancy was collected from female nurses for the most recent pregnancy since 1993. Of 11,178 eligible respondents, 9547 (85%) indicated willingness to participate in the occupational study, and 8461 of those (89%) returned the questionnaire, for an overall participation rate of 76%. Of these, 7688 women had pregnancies that were eligible for analysis. RESULTS: Participants reported 6902 live births and 786 (10%) spontaneous abortions. Compared with women who reported usually working "days only" during their first trimester, women who reported usually working "nights only" had a 60% increased risk of spontaneous abortion (RR = 1.6; 95% confidence interval [CI] = 1.3-1.9). A rotating schedule, with or without night shifts, was not associated with an increase in risk (RR = 1.2 [CI = 0.9-1.5] and 1.0 [CI = 0.8-1.2], respectively). Women who reported working more than 40 hours per week during the first trimester were also at increased risk of spontaneous abortion (1.5; 1.3-1.7) compared with women working 21-40 hours, even after adjustment for work schedule. CONCLUSIONS: Nightwork and long work hours may be associated with an increased risk of spontaneous abortion. Further studies are needed to determine whether hormonal disturbances attributed to night work affect pregnancy outcome.  相似文献   

13.
PURPOSE Clinical innovations have made it more feasible to incorporate early abortion into family medicine, yet the outcomes of early abortion procedures in this setting have not been well studied. We wished to assess the outcomes of first-trimester medication and aspiration abortion procedures by family physicians.METHODS Prospective observational cohort study conducted from August 2001 to February 2005 of 2,550 women who sought pregnancy termination in 4 clinical practices of family medicine departments and 1 private office/training site.RESULTS The rate of successful uncomplicated procedures for medication was 96.5% (95% confidence interval [CI], 95.5%–97.0%) and for aspiration was 99.9% (CI, 99.3%–1). Adverse events and complications of medication abortions were failed procedure (ongoing pregnancy; n = 19, 1.45%); incomplete abortion (n = 16, 1.22%); hemorrhage (n = 9, 0.69%); and patient request for aspiration (n = 1, 0.08%). One (0.08%) missed ectopic pregnancy was seen among patients receiving medication. Four types of adverse outcomes were encountered with aspiration: incomplete abortion requiring re-aspiration (n = 21, 1.83%); hemorrhage during the procedure (n = 4, 0.35%); missed ectopic pregnancy (n = 3, 0.26%); and minor endometritis (n = 1, 0.09%). Missed ectopic pregnancies were successfully treated in the inpatient setting without mortality (overall hospitalization rate of 0.16 of 100). All other complications were managed within outpatient family medicine sites. Rates of complication did not vary by experience of physician or by site of care (residency vs private practice).CONCLUSIONS Complications of medication and aspiration procedures occurred at a low rate, and most were minor and managed without incident.  相似文献   

14.
Induced abortion and breast cancer risk   总被引:3,自引:0,他引:3  
Results from case-control studies suggest that induced abortion may be associated with a small increase in risk of breast cancer. While risk estimates from cohort studies have generally not observed such an association, these studies have had limited information regarding abortion and possible confounding variables. Therefore, we conducted a study among a cohort of post-menopausal women from whom detailed information regarding pregnancy outcomes as well as risk factors for breast cancer had been collected. The study sample included 37,247 Iowa Women's Health Study participants, 55-64 years of age at baseline in 1986, who reported no history of breast, or other, cancer (except non-melanoma skin cancer), and for whom information regarding pregnancy outcomes (that is, live birth, stillbirth, spontaneous abortion, ectopic pregnancy or induced abortion) was available. We used linkage with records of the State Health Registry of Iowa, part of the National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) program, to estimate the incidence of breast cancer among cohort members through 1995. We calculated age-adjusted relative risks and 95% confidence intervals using Cox proportional hazards regression. Only 653 women (1.8%) reported an induced abortion. The age-adjusted relative risk of breast cancer among women with prior induced abortion compared with those without was 1.1 (95% CI = 0.8-1.6). Relative risks were higher among women whose age at first abortion was less than 20 or at least 30 years, for those whose abortion took place after their first birth or who never gave birth, and for those with early termination (0-2 months). These estimates varied from 1.3-1.7, but the confidence intervals around each were wide. Since most women in this cohort were beyond their reproductive years when abortion became legal in 1973, the low prevalence of induced abortion argues for a cautious interpretation.  相似文献   

15.
Objectives: The objective of this study was to identify the determinants of late prenatal care (PNC) initiation among minority women in Washington, DC. Methods: DC-resident, African American women (n = 303) were recruited at 14 PNC facilities, representing the various types of PNC facilities located in DC: 4 hospital-based clinics, 5 community-based clinics, and 5 private practices. The women were interviewed at their first prenatal care visits to determine their perceptions of 63 barriers, motivators and facilitators influencing PNC initiation; substance use; and sociodemographic background. PNC initiation was classified as early (prior to the 20th week of gestation) or late (after the 20th week of gestation). The responses of women who initiated PNC early versus late were compared using bivariate and multivariate statistical procedures. Classification and Regression Trees analysis was used to identify groups at risk of late initiation. Results: Variables contributing to late PNC initiation included maternal age not between 20 and 29 years, unemployment, no history of previous abortions, consideration of abortion, lack of money to pay for PNC, and no motivation to learn how to protect ones health. Three risk groups for late PNC initiation included 1) women considering abortion and not employed outside their homes; 2) women not considering abortion who had no previous abortion experience; and 3) teenagers not considering abortion and with no previous abortions. Conclusions: The results of this study indicate that psychosocial barriers are more important than structural barriers. Of the psychosocial barriers, the major determinants of late PNC initiation were consideration of abortion and previous abortion experience.  相似文献   

16.
Watson LF, Rayner J‐A, King J, Jolley D, Forster D, Lumley J. Modelling prior reproductive history to improve prediction of risk for very preterm birth. Paediatric and Perinatal Epidemiology 2010. In published studies of preterm birth, analyses have usually been centred on individual reproductive events and do not account for the joint distributions of these events. In particular, spontaneous and induced abortions have often been studied separately and have been variously reported as having no increased risk, increased risk or different risks for subsequent preterm birth. In order to address this inconsistency, we categorised women into mutually exclusive groups according to their reproductive history, and explored the range of risks associated with different reproductive histories and assessed similarities of risks between different pregnancy histories. The data were from a population‐based case–control study, conducted in Victoria, Australia. The study recruited women giving birth between April 2002 and April 2004 from 73 maternity hospitals. Detailed reproductive histories were collected by interview a few weeks after the birth. The cases were 603 women who had had a singleton birth between 20 and less than 32 weeks gestation (very preterm births including terminations of pregnancy) and the controls were 796 randomly selected women from the population who had had a singleton birth of at least 37 completed weeks gestation. All birth outcomes were included. Unconditional logistic regression was used to assess the association of very preterm birth with type and number of prior abortions, prior preterm births and sociodemographic factors. Using the complex combinations of prior pregnancy experiences of women (including nulligravidity), we showed that a history of prior childbirth (at term) with no preterm births gave the lowest risk of very preterm birth. With this group as the reference category, odds ratios of more than two were associated with all other prior reproductive histories. There was no evidence of difference in risk between types of abortion (i.e. spontaneous or induced) although the risk increased if a prior preterm birth had also occurred. There was an increasing risk of very preterm birth associated with increasing numbers of abortions. This method of data analysis reveals consistent and similar risks for very preterm birth following spontaneous or induced abortions. The findings point to the need to explore commonalities rather than differences in regard to the impact of abortion on subsequent births.  相似文献   

17.
Abortion,changed paternity,and risk of preeclampsia in nulliparous women   总被引:1,自引:0,他引:1  
A prior birth confers a strong protective effect against preeclampsia, whereas a prior abortion confers a weaker protective effect. Parous women who change partners in a subsequent pregnancy appear to lose the protective effect of a prior birth. This study (Calcium for Preeclampsia Prevention Trial, 1992-1995) examines whether nulliparous women with a prior abortion who change partners also lose the protective effect of the prior pregnancy. A cohort analysis was conducted among participants in this large clinical trial of calcium supplementation to prevent preeclampsia. Subjects were nulliparous, had one prior pregnancy or less, delivered after 20 weeks' gestation, and were interviewed at 5-21 weeks about prior pregnancies and paternity. Women without a history of abortion served as the reference group in logistic regression analyses. Women with a history of abortion who conceived again with the same partner had nearly half the risk of preeclampsia (adjusted odds ratio = 0.54, 95 percent confidence interval: 0.31, 0.97). In contrast, women with an abortion history who conceived with a new partner had the same risk of preeclampsia as women without a history of abortion (adjusted odds ratio = 1.03, 95 percent confidence interval: 0.72, 1.47). Thus, the protective effect of a prior abortion operated only among women who conceived again with the same partner. An immune-based etiologic mechanism is proposed, whereby prolonged exposure to fetal antigens from a previous pregnancy protects against preeclampsia in a subsequent pregnancy with the same father.  相似文献   

18.
《Contraception》2012,85(6):609-614
BackgroundThe aim of this study is to explore the effect of first-trimester mifepristone-induced abortion on vaginal bleeding in subsequent pregnancy.Study DesignThis observational cohort study was conducted during 1998–2001 at antenatal clinics in Beijing, Chengdu, and Shanghai, China. The study enrolled 4,931 women with one previous mifepristone-induced abortion, 4,925 women with no history of induced abortion, and 4,800 women with one previous surgical abortion and followed them through pregnancy and childbirth.ResultsThe rates of vaginal bleeding in pregnant women with a history of medical abortion, no abortion, and surgical abortion were 16.5%, 13.9%, and 17.3%, respectively. The women with medical abortion had a higher risk (adjusted relative risk (aRR)=1.17, 95% confidence interval (CI): 1.07, 1.29) of vaginal bleeding compared with those with no abortion but similar risk to prior surgical abortion. When the correlation between medical abortion and vaginal bleeding was examined by period, increased risk was observed only in the early period (<16 gestational weeks) (aRR=1.25, 95% CI: 1.12, 1.39). The comparison between subgroups of medical abortion and no abortion showed that the observed risks increased particularly in those with abortion at gestational age ≤7 weeks (aRR=1.33, 95% CI: 1.18, 1.49), those followed by a postabortion curettage (aRR=1.58, 95% CI: 1.37, 1.84) or complications (aRR=1.99, 95% CI: 1.67, 2.37). There was no difference between women with medical abortion and women with surgical abortion in the occurrence of vaginal bleeding for either period.ConclusionsOne previous mifepristone-induced abortion increased the risk of vaginal bleeding in early gestation period of subsequent pregnancy compared with no abortion, especially if abortion occurred before 7 weeks of gestation and was followed by a curettage or complications.  相似文献   

19.
目的 了解浙江省嘉兴地区初孕妇女自然流产状况及分布特征.方法 资料来源于北京大学生育健康研究所嘉兴地区围产保健监测及自然流产数据.研究对象为嘉兴地区1993-1995年登记的准备结婚及生育并最终怀孕(不包括人工流产、宫外孕及葡萄胎)的初孕妇女14769名.结果 嘉兴地区初孕妇女自然流产率为9.8%(1454/14769,95%CI:9.3~10.3),平均妊娠诊断孕周为(7.6±2.1)周,平均流产孕周为(10.1±3.1)周.早期(≤12周)自然流产率为7.3%(95%CI:6.8~7.7),占总流产的73.7%.流产集中发生在8~13周,占37.7%.经多因素Cox回归分析,生育年龄≥30岁、农民、文化程度高者自然流产率较高.结论 嘉兴地区初孕妇女自然流产率高于国内其他地区;自然流产主要发生在8~13孕周.  相似文献   

20.
Women with a history of recurrent spontaneous abortions (repeaters) are compared with women who have had live births and no spontaneous abortions (multiparae) and women who have had live births and only one spontaneous abortion (sporadics) to identify characteristics of the women and their abortuses that might predict subsequent fetal loss. A number of risk factors for recurrent spontaneous abortion have been identified: the loss of a chromosomally normal conception, loss after the first trimester of pregnancy, a delay in conceiving prior to the study pregnancy, a diagnosis of cervical incompetence, and a history of very low birthweight deliveries. The odds ratios associated with being a repeater vary from 1.4 to 5.6 depending on the number of characteristics present.  相似文献   

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