Characteristics of women with recurrent spontaneous abortions and women with favorable reproductive histories.

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.     

Abortion surveillance, 1986-1987

Since 1980, the number of legal abortions reported to CDC has remained fairly stable, varying each year by less than 3%. In 1986, 1,328,112 abortions were reported; in 1987, that number increased by approximately 2% to 1,353,671. The abortion ratio for 1986 was 354 legally induced abortions per 1,000 live births; the ratio for 1987 was 356 per 1,000. The national abortion rate was 23/1,000 females ages 15-44 years for 1986 and 24/1,000 females ages 15-44 years in 1987. Abortion ratios were higher among women of black and other minority races and among women less than 15 years of age. Women undergoing legally induced abortions tended 1) to be young, white, and unmarried, 2) to have had no previous live births, and 3) to be having the procedure for the first time. In 1987, approximately half of all abortions were performed before the eighth week of gestation, and greater than 85% were performed during the first trimester of pregnancy (less than 13 weeks of gestation).     

Abortion surveillance--United States, 1989.

Since 1980, the number of legal induced abortions reported to CDC has remained stable, varying each year by < 5%. In 1989, 1,396,658 abortions were reported--a 1.9% increase from 1988. The abortion ratio for 1989 was 346 legal induced abortions/1,000 live births, and the abortion rate was 24/1,000 women ages 15-44 years. The abortion ratio was highest for black women and women of other minority racial groups and for women < 15 years of age. Overall, women undergoing abortions tended to be young, white, and unmarried; to have had no previous live births; and to be having the procedure for the first time. Approximately half of all abortions were performed before the eighth week of gestation, and 87% were before the thirteenth week of gestation. Younger women tended to obtain abortions later in pregnancy than older women. This report also includes newly reported abortion-related deaths for 1986 and 1987, as well as an update on abortion-related deaths for the period 1978-1985. Ten deaths in 1986 and six deaths in 1987 were associated with legal induced abortion. The case-fatality rate in 1986 was 0.8 abortion-related deaths/100,000 legal induced abortions and 0.4/100,000 in 1987.     

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.     

Late sequelae of induced abortion: complications and outcome of pregnancy and labor.

The effects of previous induced abortion on pregnancy, labor and outcome of pregnancy were measured in a prospective study of 11,057 pregnancies to West Jerusalem mothers who were interviewed during pregnancy and who subsequently delivered a single live or stillborn infant. The 752 mothers who reported one or more induced abortions in the past were more likely, at the same interview, to report bleeding in each of the first 3 months of the present pregnancy. They were subsequently less likely to have a normal delivery and more of them needed a manual removal of the placenta or other intervention in the third stage of labor. In births following induced abortions, the relative risk of early neonatal death was doubled, while late neonatal deaths showed a 3- to 4-fold increase. There was a significant increase in the frequency of low birthweight, compared to births in which there was no history of previous abortion. There were increases in major and minor congenital malformations, but no significant changes in stillbirth or post-neonatal death rates, nor in mean birthweight or sex ratio. When the effects of other variables were taken into account, there were no significant changes in frequency following an induced abortion as to: ABO and rhesus isoimmunization, toxemia, hydramnios, premature rupture of membranes, induction of labor, breech or vacuum delivery, cesarean section, breech presentation, placenta previa, placental abruption, cord prolapse, cord anomalies, fetal distress or asphyxia, post-partum hemorrhage.     

The impact of short interpregnancy intervals on pregnancy outcomes in a low-income population.

OBJECTIVES: The objective of this study was to determine whether the length of the interval between pregnancies was associated with either preterm birth or intrauterine growth retardation in a low-income, largely Black population. METHODS: The study population consisted of 4400 women who had received prenatal care in county clinics and had two consecutive singleton births between 1980 and 1990. RESULTS: Interpregnancy intervals were positively associated with age and negatively associated with the trimester in which care was initiated in the second pregnancy. Whites had shorter intervals than non-Whites. The percentage of preterm births increased as the length of the interpregnancy interval decreased, but only for women who had not had a previous preterm birth. The association between interval and preterm birth was maintained when other factors associated with preterm birth were controlled. There was no significant relationship between intrauterine growth retardation and interpregnancy interval. CONCLUSIONS: Women, particularly those who are poor and young, should be advised of the potential harm to their infants of short interpregnancy intervals.     

Previous abortion and the risk of low birth weight and preterm births

OBJECTIVE: To investigate the association between previous abortion and low birth weight (LBW) and preterm birth (PB). METHOD: The study examined live, singleton births using data from the United States Collaborative Perinatal Project. Logistic regression was used to control for obstetric and medical history, and lifestyle and demographic factors. RESULT: Compared with women with no history of abortion, women who had one, two and three or more previous abortions were 2.8 (95% CI 2.48 to 3.07), 4.6 (95% CI 3.94 to 5.46) and 9.5 (95% CI 7.72 to 11.67) times more likely to have LBW, respectively. The risk for PB was also 1.7 (95% CI 1.52 to 1.83), 2.0 (95% CI 1.73 to 2.37) and 3.0 (95% CI 2.47 to 3.70) times higher for women with a history of one, two and three or more previous abortions, respectively. CONCLUSION: Previous abortion is a significant risk factor for LBW and PB, and the risk increases with the increasing number of previous abortions. Practitioners should consider previous abortion as a risk factor for LBW and PB.     

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.     

Comparison of gestational age at birth based on last menstrual period and ultrasound during the first trimester

Reported last menstrual period (LMP) is commonly used to estimate gestational age (GA) but may be unreliable. Ultrasound in the first trimester is generally considered a highly accurate method of pregnancy dating. The authors compared first trimester report of LMP and first trimester ultrasound for estimating GA at birth and examined whether disagreement between estimates varied by maternal and infant characteristics. Analyses included 1867 singleton livebirths to women enrolled in a prospective pregnancy cohort. The authors computed the difference between LMP and ultrasound GA estimates (GA difference) and examined the proportion of births within categories of GA difference stratified by maternal and infant characteristics. The proportion of births classified as preterm, term and post‐term by pregnancy dating methods was also examined. LMP‐based estimates were 0.8 days (standard deviation = 8.0, median = 0) longer on average than ultrasound estimates. LMP classified more births as post‐term than ultrasound (4.0% vs. 0.7%). GA difference was greater among young women, non‐Hispanic Black and Hispanic women, women of non‐optimal body weight and mothers of low‐birthweight infants. Results indicate first trimester report of LMP reasonably approximates gestational age obtained from first trimester ultrasound, but the degree of discrepancy between estimates varies by important maternal characteristics.     

Safety of MenACWY-CRM vaccine exposure during pregnancy

BackgroundAlthough the meningococcal conjugate MenACWY-CRM vaccine is not approved for use in pregnant women, unintentional exposure during pregnancy can occur, especially during early pregnancy among women of child-bearing age. This study provides safety information about inadvertent MenACWY-CRM vaccination during pregnancy.MethodsThe evaluated population consisted of pregnant female members of Kaiser Permanente Southern California who inadvertently received MenACWY-CRM at 11–21 years of age during 09/30/2011-06/30/2013 within 28 days prior to conception or during pregnancy. Chart abstraction was conducted to identify pregnancy and birth outcomes, including spontaneous and induced abortions, preterm births, low weight births, and major congenital malformations (MCMs).ResultsThere were 92 women who received MenACWY-CRM during the pregnancy exposure period, mainly during the first trimester (76.1%). Hispanics represented the largest race/ethnicity category (68.5%). Among the known pregnancy outcomes (n = 66; excluding induced abortions and unknown pregnancy outcomes), the prevalence of spontaneous abortions was 18.2% (n = 12). Among live born infants (n = 55; from 54 pregnancies), 14.5% (n = 8) were born preterm (<37 weeks gestation) and 9.1% (n = 5) had a low birthweight (<2500 g). The prevalence rate of MCMs among live born infants (n = 55) was 1.8% (n = 1).ConclusionsThis study provides baseline prevalence estimates of spontaneous abortions, preterm births, low weight births, and MCMs among women inadvertently exposed to MenACWY-CRM during the pregnancy period. These estimates appear to be comparable with U.S. background prevalence estimates.     

Induced abortion and risk of subsequent miscarriage

BACKGROUND: To evaluate the impact of surgically induced first-trimester abortion on the risk of miscarriage in a subsequent pregnancy. METHODS: The study is a pregnancy cohort study. It was conducted among 15 general hospitals or maternity and infant health institutes in Shanghai, China from November 1993 to March 1998. The abortion cohort consisted of pregnant women whose previous pregnancies were terminated by vacuum aspiration (98%). The reference cohort consisted of primigravidae. Subjects were recruited at 35-63 days of gestational age. A total of 2953 pregnant women were enrolled; 1502 in the abortion cohort, 1451 in the reference cohort. RESULTS: There were only 62 women lost to follow-up. The remaining 2891 women had 2732 live births, and 137 miscarriages. About 5.5% of pregnancies in the abortion cohort were miscarried and 4.0% in the reference cohort. Once potential confounders were controlled for by logistic regression, odds ratio (OR) of miscarriage between the abortion cohort and the reference cohort was 1.55 (95% CI: 1.08-2.23). The adjusted OR were 2.44 (95% CI: 1.16-5.15) among women who were recruited within 49 days of gestational age, and 1.72 (95% CI: 1.09-2.72) for the first-trimester miscarriage. CONCLUSIONS: Induced abortion by vacuum aspiration is associated with an increased risk of first-trimester miscarriage in the subsequent pregnancy.     

Does lack of multinutrient supplementation during early pregnancy increase vulnerability to alcohol-related preterm or small-for-gestational-age births?

The objective of this study was to assess whether women who do not take multinutrient supplements during early pregnancy are more susceptible to the effects of low-to-moderate alcohol consumption on preterm birth and small-for-gestational-age birth (SGA) compared to women who do take multinutrients. This analysis included 800 singleton live births to mothers from a cohort of pregnant women recruited for a population-based cohort study conducted in the Kaiser Permanente Medical Care Program in Northern California. Participants were recruited in their first trimester of pregnancy and information about their alcohol use and supplement intake during pregnancy was collected. Preterm birth (n = 53, 7%) was defined as a delivery prior to 37 completed weeks of gestation and SGA birth (n = 124, 16%) was defined as birth weight less than the 10th percentile for the infant’s gestational age and sex compared to US singleton live births. A twofold increase in the odds of SGA birth attributed to low-to-moderate alcohol intake was found among multinutrient supplement non-users (95% CI: 1.1, 5.3). Yet, among multinutrient supplement users, there was no increased risk of an SGA birth for women who drank low-to-moderately compared to women who abstained (aOR: 0.97, 95% CI: 0.6, 1.6). Similar results emerged for preterm birth. Our findings provide marginal evidence that multinutrient supplementation during early pregnancy may modify the risk of SGA births and preterm birth associated with alcohol consumption during pregnancy and may have important implications for pregnant women and women of child-bearing age. However, future research needs to be conducted.     

Work schedule during pregnancy and spontaneous abortion

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.     

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).     

Risk of spontaneous abortion in Italy, 1978-1995, and the effect of maternal age, gravidity, marital status, and education

This paper describes the trend in the risk of spontaneous abortion in Italy from 1974 to 1995. There was a dramatic decline in the risk after the law that legalized induced abortion was passed in 1978, which implies that probably many induced abortions performed before 1978 were registered as spontaneous abortions. Data for 1991 have been extracted from the Italian national registers of births and abortions and analyzed to investigate the effects of maternal age, gravidity, marital status, and education on the risk of spontaneous abortion. In comparison with women under age 20 years, the risk is found to be increased for women aged 35-39 (odds ratio = 1.45) and women over age 40 (odds ratio = 3.10). The odds ratio is almost 2 for women who have been pregnant two or more times previously. Unmarried women have an increased risk (odds ratio = 1.33), but no important effect of education was observed. There is an important interaction between maternal age and gravidity. The risk of spontaneous abortion is excessively high for young women with high gravidity. It is hypothesized that this could be due to the effect of short intervals between pregnancies.     

Moderate alcohol intake in pregnancy and the risk of spontaneous abortion

Women attending routine antenatal care at Aarhus University Hospital, Denmark, from 1989 to 1996 were eligible for this cohort study on the association between alcohol intake in pregnancy and the risk of spontaneous abortion. We included 24 679 singleton pregnancies in the study. We used Cox regression analyses with delayed entry for the analyses. We found an increased risk of spontaneous abortion in the first trimester (7-11 completed weeks of gestation) for women consuming > or =5 drinks/week. We found no association between alcohol intake and spontaneous abortion during the second trimester. Common methodological problems in relation to studies on spontaneous abortions are discussed, as are problems with possible under-reporting of alcohol consumption. We conclude that women consuming > or =5 drinks/week are at increased risk of first trimester spontaneous abortion.     

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.     

Abortion surveillance, United States, 1984-1985

Since 1983, the number of legal abortions reported to CDC increased by 5% to 1,333,521 in 1984; in 1985, that number decreased by less than 1% to 1,328,570. The national abortion rate was the same for both years-24 per 1,000 females ages 15-44 years. The abortion ratio for 1984 was 364 legally induced abortions per 1,000 live births; the ratio for 1985 was 354 per 1,000. Abortion ratios were higher among women of black and other minority races and among women younger than 15 years of age. Women undergoing legally induced abortions tended 1) to be young, white, and unmarried, 2) to have had no previous live births, and 3) to be having the procedure for the first time. Curettage was the procedure used in 96% of the reported cases. Eleven deaths were associated with legally induced abortions in 1984, and six in 1985. The case-fatality rate in 1985 was 0.5 deaths per 100,000 legally induced abortions, down from the 0.8 per 100,000 reported in 1983 and 1984. Overall, since 1980, the numbers and rates of abortion have had only slight year-to-year fluctuations. The steady increase in the percentage of repeat abortions since 1972 reflects the ongoing availability of legal abortions. Since the beginning of CDC's abortion mortality surveillance, the number of deaths related to legal abortions has decreased 75%, from 24 deaths in 1972 to six deaths in 1985.     

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.     

The associations of maternal caffeine consumption and nausea with spontaneous abortion

To examine whether maternal caffeine consumption is associated with the risk of spontaneous abortion, we analyzed data from a population-based prospective study. The study population comprised 575 women delivering singleton livebirths and 75 women who had spontaneous abortions. The subjects were predominantly white, middle-class women enrolled before pregnancy. Study participants were traced to delivery of a liveborn, singleton infant or a spontaneous abortion. Of the 71 women who did not experience nausea, 29.6% had a spontaneous abortion, compared with 7.2% of 514 women who did experience nausea. Maternal caffeine consumption before pregnancy, or in women without nausea, did not increase the risk of spontaneous abortion, whereas maternal caffeine consumption during the first trimester after nausea started might increase risk of spontaneous abortion (risk ratio = 5.4, 95% confidence interval = 2.0-14.6 for caffeine consumption > or = 300 mg per day compared with < 20 mg per day). These results suggest that maternal caffeine consumption during pregnancy may influence fetal viability in women with nausea.