Ectopic pregnancy and prior induced abortion.

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.     

Risk of ectopic pregnancy and previous induced abortion.

OBJECTIVES: This study investigated the role of prior history of induced abortion in subsequent ectopic pregnancies. METHODS: Data from two French case-control studies were used to examine the effect of induced abortion on ectopic pregnancy risk. Case patients (n = 570) were women admitted for ectopic pregnancy during the study period; controls (n = 1385) were women who delivered in the same center. RESULTS: The analysis among women with no previous ectopic pregnancy showed that, after control for the main ectopic pregnancy risk factors, prior induced abortion was associated with an increased risk of ectopic pregnancy (odds ratio [OR] = 1.5, 95% confidence interval [CI] = 1.0, 2.0); there was a significant trend between number of previous induced abortions and ectopic pregnancy risk (ORs = 1.4 for 1 previous induced abortion and 1.9 for 2 or more). CONCLUSIONS: This study suggests that induced abortion may be a risk factor for ectopic pregnancy for women with no previous ectopic pregnancy, particularly in the case of women who have had several induced abortions.     

Ectopic pregnancy and prior induced abortion

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.     

Induced abortion: not an independent risk factor for pregnancy outcome, but a challenge for health counseling

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.     

Abortion and its effect on risk of preeclampsia and transient hypertension

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.     

Risk factors for ectopic pregnancy: a comprehensive analysis based on a large case-control,population-based study in France

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.     

Repeat abortion: is it a problem?

As the number of Canadian women who have had induced abortions increases with each succeeding year, the number at risk--and the actual incidence--of repeat abortion also increases. Some researchers have argued that women who have more than one induced abortion are less well adjusted, others that they are less willing to use contraceptives, perhaps because of anxiety about sexuality. Still others have suggested that repeat abortion is unrelated to the psychology or attitudes of individual women, but rather is an inevitable result of imperfect contraceptives, imperfect contraceptive practice and the availability of legal abortion for the termination of unwanted pregnancies. A group of 580 women seeking abortions were interviewed at the Montreal General Hospital and given a number of psychological tests. About one in five of these women were having repeat abortions. The women having repeat abortions were older, less likely to be married and more tolerant of legal abortion than were women having their first abortions. They also had intercourse more frequently than the first-abortion patients. Women obtaining a repeat abortion were slightly more likely to have been using contraceptives at the time they became pregnant, but they did not differ from first-abortion patients in the types of methods that they used. On no other social or demographic characteristics, measures of psychological adjustment or attitudes about sexuality were there any important differences between the groups. A more complex statistical analysis reveals that the two most important factors differentiating first-abortion and repeat-abortion patients are age and coital frequency--both of which are variables that reflect added exposure to the risk of unintended pregnancy.(ABSTRACT TRUNCATED AT 250 WORDS)     

Race-specific patterns of abortion use by American teenagers.

Between 1972 and 1978, as legal abortion became more widely available nationally, abortion rates (abortions per 1,000 women) and ratios (abortions per 1,000 live births) increased for all American teenagers; from 1972 to 1975, the rates and ratios for teenagers for Black and other races increased faster than those for White teenagers. For all seven years, abortion rates were higher for teenagers of Black and other races than for white teenagers. This reflected both higher proportions of sexually active teenagers of Black and other races and a greater risk of pregnancy in these teenagers compared with White teenagers. Race-specific differences in legal abortion ratios narrowed during the seven-year interval, as did differences in alternative outcomes of teenage premarital pregnancies (term births, illegal abortions).     

Abortion among young women and subsequent life outcomes

CONTEXT: Young women frequently cite concerns about the effects of unplanned pregnancies on future life course outcomes, including education, employment and relationships, as reasons for seeking abortion. There is relatively little evidence as to whether abortion leads to improved life course outcomes for young women who choose this option. METHODS: Data from 492 women participating in a 25-year longitudinal study of a New Zealand birth cohort were used in regression models that examined the relationship between pregnancy and abortion history prior to age 21 and selected social and economic outcomes at ages 21-25. RESULTS: Compared with young women who became pregnant before age 21 but did not seek an abortion, young women who had an abortion had significantly better outcomes on six out of 10 measures spanning education, income, welfare dependence and domestic violence. Adjustment for confounding factors indicated that most of these differences were explained by family, social and educational characteristics that were present prior to pregnancy. Nonetheless, even after adjustment for confounding factors, young women who had abortions had higher levels of subsequent educational achievement than those who became pregnant but did not have abortions. CONCLUSIONS: Abortion may mitigate some effects of early unplanned pregnancy. However, further study of its potential risks and benefits is needed so that women can make fully informed decisions as to whether to terminate unintended pregnancies.     

Child-bearing after induced abortion: reassessment of risk.

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.     

Examining the association of abortion history and current mental health: A reanalysis of the National Comorbidity Survey using a common-risk-factors model

Using the US National Comorbidity Survey (NCS), Coleman, Coyle, Shuping, and Rue (2009) published an analysis indicating that compared to women who had never had an abortion, women who had reported an abortion were at an increased risk of several anxiety, mood, and substance use disorders. Here, we show that those results are not replicable. That is, using the same data, sample, and codes as indicated by those authors, it is not possible to replicate the simple bivariate statistics testing the relationship of ever having had an abortion to each mental health disorder when no factors were controlled for in analyses (Table 2 in Coleman et al., 2009). Furthermore, among women with prior pregnancies in the NCS, we investigated whether having zero, one, or multiple abortions (abortion history) was associated with having a mood, anxiety, or substance use disorder at the time of the interview. In doing this, we tested two competing frameworks: the abortion-as-trauma versus the common-risk-factors approach. Our results support the latter framework. In the bivariate context when no other factors were included in models, abortion history was not related to having a mood disorder, but it was related to having an anxiety or substance use disorder. When prior mental health and violence experience were controlled in our models, no significant relation was found between abortion history and anxiety disorders. When these same risk factors and other background factors were controlled, women who had multiple abortions remained at an increased risk of having a substance use disorder compared to women who had no abortions, likely because we were unable to control for other risk factors associated with having an abortion and substance use. Policy, practice, and research should focus on assisting women at greatest risk of having unintended pregnancies and having poor mental health—those with violence in their lives and prior mental health problems.     

育龄女性人工流产史与妊娠等待时间的相关性研究

目的:探讨育龄女性人工流产史与妊娠等待时间(TTP)关系。方法:采用回顾性队列研究方法,将2013年1月-2017年12月参加深圳市孕前优生健康检查且符合条件的44672例育龄女性作为研究对象,以20608例既往有人工流产史者为暴露组(其中14762例有1次人工流产史,5846例有≥2次人工流产史),以24064例无人工流产史者为非暴露组。采用Kruskal-walls检验和χ2检验比较不同组间的基线特征,Kaplan-Meier法计算每个月经周期的累计妊娠率,使用Cox模型估计育龄女性人工流产史对TTP的影响。结果:既往无人工流产史的育龄女性12个月经周期的累计妊娠率为(32.6%),低于既往有1次(38.9%)和≥2次人工流产史(34.0%)者。对影响因素进行调整后,与无人工流产史的育龄女性相比,有1次和≥2次人工流产史的女性生育力分别升高19.0%(FOR=1.190,95%CI 1.147~1.234)和21.5%(FOR=1.215,95%CI 1.153~1.280)。结论:有人工流产史的育龄女性生育力较高,TTP未见延长。针对这一生育力较高的特定人群,应做好科学避孕指导工作,避免多次意外妊娠后反复实施人工流产术对其生殖健康产生不良影响。     

Estimates of pregnancies and pregnancy rates for the United States, 1976-85.

After increasing by 9 per cent in the period 1976-80 in the United States, pregnancy rates declined by 4 per cent between 1980 and 1984 (from 111.9 to 107.3 pregnancies per 1,000 women aged 15-44 years). Between 1984 and 1985, the rate rose by less than 1 per cent to 108.2. More detailed data by age and race, available only through 1983, indicate that the decline in the 1980-83 period was not shared by all age groups. For example, pregnancy rates continued to increase for women in their thirties, and teenage pregnancy remained substantially the same. In 1983, 61 per cent of all pregnancies ended in live birth, 26 per cent in induced abortion, and 13 per cent in fetal loss. Pregnancy rates in that year were two-thirds higher for women of races other than White than for White women, and pregnancies of other-than-White women were more likely to terminate as an induced abortion or fetal loss. However, White teenagers and teenagers of other races were about equally likely to have their pregnancy end in induced abortion or fetal loss.     

Induced abortion and breast cancer risk

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.     

Adverse reproductive outcomes among female veterinarians

Because female veterinarians are exposed to several known reproductive hazards, the authors conducted a reproductive survey of all female graduates of a US veterinary school (n = 537) and law school (comparison group, n = 794). Analysis was confined to pregnancies completed after the second year of professional school and from 1966 to 1986. Based on one randomly chosen eligible pregnancy per woman (veterinarians, n = 176; lawyers, n = 229), spontaneous abortion rates, adjusted for elective abortions, were 13.3% for the veterinarians and 15.1% for the lawyers; these did not differ significantly. A Cox life table regression model controlling for age, smoking, alcohol use, and prior spontaneous abortion also showed no significant difference in spontaneous abortion rates between the two populations. Using all pregnancies, veterinarians who reported performing five or more radiographic examinations per week had a marginally elevated risk of spontaneous abortion, but the statistical significance disappeared when analysis was limited to one random pregnancy per woman. For one random eligible birth per woman, the mean birth weight did not differ significantly between the veterinarians and lawyers, even after controlling for possible confounders in regression analyses. A higher rate of reportable birth defects was observed among the veterinarians than among the lawyers (relative risk = 4.2, 95% confidence interval 1.2-15.1), but this unexpected result must be considered hypothesis-generating. The authors did not find an overall increased risk for spontaneous abortion or low birth weight infants among veterinarians compared with lawyers, but veterinarians who reported performing five or more radiographic examinations per week may have been at increased risk for spontaneous abortion.     

Induced abortion and low birthweight in the following pregnancy

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.     

Abortion surveillance--United States, 1997.

PROBLEM/CONDITION: In 1969, CDC began abortion surveillance to document the number and characteristics of women obtaining legal induced abortions, to monitor unintended pregnancy, and to assist efforts to identify and reduce preventable causes of morbidity and mortality associated with abortions. REPORTING PERIOD COVERED: This report summarizes and reviews information reported to CDC regarding legal induced abortions obtained in the United States in 1997. DESCRIPTION OF SYSTEM: For each year since 1969, CDC has compiled abortion data by state where the abortion occurred. The data are received from 52 reporting areas in the United States: 50 states, the District of Columbia, and New York City. RESULTS: In 1997, a total of 1,186,039 legal abortions were reported to CDC, representing a 3% decrease from the number reported for 1996. The abortion ratio was 306 legal induced abortions per 1,000 live births, and since 1995, the abortion rate has remained at 20 per 1,000 women aged 15-44 years. The availability of information about characteristics of women who obtained an abortion in 1997 varied by state and by the number of states reporting each characteristic. The total number of legal induced abortions by state is reported by state of residence and state of occurrence; characteristics of women obtaining abortions in 1997 are reported by state of occurrence. Women who were undergoing an abortion were more likely to be young (i.e., aged < 25 years), white, and unmarried; approximately one half were obtaining an abortion for the first time. More than one half of all abortions for which gestational age was reported (55%) were performed at < or = 8 weeks of gestation, and 88% were performed before 13 weeks. Overall, 18% of abortions were performed at the earliest weeks of gestation (< or = 6 weeks), 18% at 7 weeks of gestation, and 20% at 8 weeks of gestation. From 1992 through 1997, increases have occurred in the percentage of abortions performed at the very early weeks of gestation. Few abortions were provided after 15 weeks of gestation--4% of abortions were obtained at 16-20 weeks, and 1.4% were obtained at > or = 21 weeks. A total of 19 reporting areas submitted information regarding abortions performed by medical (nonsurgical) procedures, comprising < 1% of procedures reported by all states. Younger women (i.e., aged < or = 24 years) were more likely to obtain abortions later in pregnancy than were older women. INTERPRETATION: From 1990 through 1995, the number of abortions declined each year; in 1996, the number increased slightly, and in 1997, the number of abortions in the United States declined to it lowest level since 1978. PUBLIC HEALTH ACTIONS: The number and characteristics of women who obtain abortions in the United States should continue to be monitored so that trends in induced abortion can be assessed and efforts to prevent unintended pregnancy can be evaluated.     

高海拔地区藏族育龄妇女自然流产的流行病学特点

目的 了解中国高海拔地区15～49岁藏族育龄妇女自然流产状况。方法 采用横断面调查设计和分层多阶段抽样法获得样本，采用问卷调查西藏地区15～49岁藏族育龄妇女的生育史。结果 共调查3741名15～49岁的藏族育龄妇女，共计10245次妊娠，报告的自然流产386次，自然流产发生率为3墙％，城市妇女显著高于农村妇女，农牧区之间差异无统计学意义，育龄妇女发生自然流产的风险在控制了可能的影响因素后随着海拔高度的增加而增高。居住在海拔4500m以上的育龄妇女发生自然流产的风险是居住在海拔3500m以下妇女的近2倍多。年龄和妊娠的次数显著与自然流产的发生有正相关关系，35岁以上的育龄妇女和多次妊娠的妇女发生自然流产的风险增大。结论 高海拔可能独立的影响藏族妇女自然流产的发生，在高海拔地区更应加强健康教育和育龄妇女孕产期保健与营养，减少妊娠次数，延长生育间隔，以减少自然流产的发生。此外，回顾性的生育史调查可能会因回忆偏性等因素而低估了自然流产的发生，但西藏地区育龄妇女的自然流产水平不一定比平原地区高很多。     

Unintended pregnancy among American women

This research note presents new estimates of the proportion of American women of reproductive age who experience unintended pregnancies, unintended births and abortions. The data are based on tabulations from the 1982 National Survey of Family Growth (NSFG) and the Alan Guttmacher Institute's 1981-1982 national survey of abortion providers. Of 6.1 million women who became pregnant in 1982, 3.7 million gave birth, 1.6 million had abortions and 0.9 million experienced miscarriages. An estimated 37% of all births in the 5 years preceding the 1982 NSFG were unintended. Applying that proportion to 1982 births results in an estimate of 1.3 million unintended births. It can be assumed that all 1.6 million abortions were terminations of unintended pregnancies. Respondents in the 1982 NSFG reported that 40% of the births they had ever had were unintended. 33% of NSFG respondents said that they had had at least 1 unintended birth during their life. Abortions were seriously underreported in the NSFG, as they have been in most other surveys. Only 47% of the abortions that occurred during the period 1977-1981 were reported. The real proportion of women of reproductive age who have ever had an abortion appears to be 21%. 65% of all women aged 40-44 in 1982 had had at least 1 unintended pregnancy, and more than 1/3 of them had had at least 1 abortion. It is probably inappropriate to view these levels as representative of the proportions of today's young women who will ever experience an unintended pregnancy or abortion. Estimates of the proportion of women who will have had abortions by age 45 indicate that 18% of women will have had a 1st abortion by age 20; 41% will have had one by age 30; and 46%, by age 45.     

Modelling sequence of prior pregnancies on subsequent risk of very preterm birth

Watson LF, Rayner J‐A, King J, Jolley D, Forster D, Lumley J. Modelling sequence of prior pregnancies on subsequent risk of very preterm birth. Paediatric and Perinatal Epidemiology 2010. The prevalence and intractability of preterm birth is known as is its association with reproductive history, but the relationship with sequence of pregnancies is not well studied. 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 having a singleton birth between 20 and <32 weeks gestation (very preterm births including terminations of pregnancy). The controls were 796 randomly selected women from the population having a singleton birth of at least 37 completed weeks gestation. Unconditional logistic regression was used to assess the association of very preterm birth with sequence of pregnancies defined by their outcome (prior abortion – spontaneous or induced, and prior preterm or term birth) with adjustment for sociodemographic factors. The outcomes of each prior pregnancy, stratified by pregnancy order, and starting with the pregnancy immediately before the index or control pregnancy, were categorised as one of abortion, preterm birth or term birth. We showed that each of these prior pregnancy events was an independent risk of very preterm birth. This finding does not support the hypothesis of a neutralising effect of a term birth after an abortion on the subsequent risk for very preterm birth and is further evidence for the cumulative or increasing risk associated with increasing numbers of prior abortions or preterm births.