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

Paternal age and maternal age are risk factors for miscarriage; results of a multicentre European study

BACKGROUND

It is well known that miscarriage risk increases with age. However, studies usually investigate only maternal age effects. We investigated both maternal age and paternal age effects on miscarriage risk to provide insight into this frequent reproductive failure.

METHODS

The last planned pregnancies (n = 3174) that ended in a birth or miscarriage were analysed in a retrospective population-based study on women aged 25-44 years in Denmark, Germany, Italy and Spain. Maternal and paternal ages were analysed together, using a single variable 'couple age' in a multivariate logistic regression analysis, with couples composed of a woman and a man both aged 20-29 years forming the reference group.

RESULTS

After adjustment for various factors (e.g. reproductive history, country), we found that the risk of miscarriage was higher if the woman was aged > or = 35 years, as has already been reported in a number of studies. However, the increase in risk was much greater for couples composed of a woman aged > or = 35 years and of a man aged > or = 40 years. Potential source of bias (especially 'reproductive compensation') are discussed.

CONCLUSIONS

The risk of an adverse pregnancy outcome is highest if both partners are advanced in age.

Legal abortion in Asturias (Spain) after the 1985 law: sociodemographic characteristics of women applying for abortion

STUDY OBJECTIVE

To describe the use of induced abortion (IA) in Asturias after its legalisation as well as the socio-demographic characteristics of women applying for abortion.

DESIGN AND SETTING

Descriptive study, population-based, using data collected by the regional abortion surveillance system for the period 1988 1994.

MAIN RESULTS

The number of IA and the abortion rate (AR) (10 per 1000 women aged 15-49) have been stable in Asturias during the study period. The highest ARs were found for women in the age group 20-34, for divorced/separated, for women with a higher educational level and for women with only one child. The proportion of pregnancies which ended in abortion was one in four; for teenagers and women over 34 years it was one in two. This proportion was also higher for women not married, students and women with two or more children. Ninety-eight percent of all abortions took place in private clinics, the woman's physical/mental health being the medical indication for these abortions. Abortion was most often performed within eight weeks of gestation (65%). Late abortion ocurred more frequently among teenagers and women of low educational level. Eighteen percent of women had repeated abortions. A high proportion (61%) of women applying for abortion had not used the Family Planning (FP) services in the previous two years; adolescents and women of low educational level had the lowest frequencies of FP use.

CONCLUSIONS

Compared with that of other European countries, the AR in Asturias was intermediate. The results regarding adolescents show the need for evaluation and promotion of sex education and contraceptive programmes. The lower and later use of abortion by women of low educational level shows inequalities that call for specific action.

Association of spontaneous abortion and other reproductive effects with work in the semiconductor industry

This study tested the hypothesis that fabrication room (fab) work in the silicon-based semiconductor industry is associated with an increased risk of spontaneous abortion (SAB). The study was conducted nationwide at 14 companies representing a spectrum of large to small manufacturers. A small increase in risk of SAB was observed among fab workers compared with nonfabrication room (nonfab) workers in two cohorts, historical (adjusted RR = 1.43, 95% confidence interval [CI] 0.95-2.09) and prospective (adjusted RR = 1.25, 95% CI = 0.63-1.76). Analysis of specific fab exposures in the historical cohort showed a consistent, dose-response association of SAB with photoresist and developer solvents, whose major component was ethylene-based glycol ethers. The consistency of our findings and the toxicological data for these agents suggest that this is a causal association. Independent associations of SAB with self-reported stress and with etching fluorides were observed and require further research. No significant decrease in fertility was observed among men or women working in fabs, but reduced fecundability was suggested for some women fab workers.

Epidemiology of isotretinoin exposure during pregnancy

BACKGROUND

Exposure to isotretinoin during pregnancy is associated with a high risk of major fetal malformations.

OBJECTIVE

Our purpose was to determine the reasons for and outcomes of in utero isotretinoin exposure.

METHODS

On the basis of 433 spontaneous reports, we describe the likely reasons these exposures occurred and the outcomes of these pregnancies. In our analysis of the outcomes of pregnancy, we separately consider the pregnancies known to us before their outcomes were determined as prospective cases.

RESULTS

Timing of conception in relation to initiation of therapy with isotretinoin was known for 396 women. Of these, 130 patients (33%) were already pregnant when they started isotretinoin. An additional 65 patients (16%) became pregnant in the first 3 weeks of isotretinoin use. Pregnancy outcomes were known on 409 pregnancies. Among these, 222 (54%) ended in elective abortion and 29 (7%) in spontaneous or missed abortion. Of 151 births, 72 (48%) were normal, 71 (47%) had congenital malformations, and 8 (5%) had abnormalities other than malformations. Of 94 prospectively ascertained pregnancies that ended in births, 28% had congenital malformations (95% confidence interval 19% to 37%). Exposure to isotretinoin during any time and for as little as one capsule within the first trimester have been associated with congenital malformations.

CONCLUSION

The high proportion of exposures in already or recently pregnant women illustrates the importance of obtaining a negative pregnancy test before the initiation of isotretinoin therapy and of delaying the commencement of isotretinoin therapy until the onset of the next menstrual period. Furthermore, the importance of reliable contraceptive methods should be emphasized to patients when isotretinoin is prescribed. Young women seem to be at an especially high risk of pregnancy exposure to isotretinoin. There is a substantial risk of congenital malformation at all therapeutic doses of isotretinoin, even when the duration of exposure is brief.

Estimating the probability of spontaneous abortion in the presence of induced abortion and vice versa

An integrated approach to estimate the total number of pregnancies that begin in a population during one calendar year and the probability of spontaneous abortion is described. This includes an indirect estimate of the number of pregnancies that result in spontaneous abortions. The method simultaneously takes into account the proportion of induced abortions that are censored by spontaneous abortions and vice versa in order to estimate the true annual number of spontaneous and induced abortions for a population. It also estimates the proportion of pregnancies that women intended to allow to continue to a live birth. The proposed indirect approach derives adjustment factors to make indirect estimates by combining vital statistics information on gestational age at induced abortion (from the 12 States that report to the National Center for Health Statistics) with a life table of spontaneous abortion probabilities. The adjustment factors are applied to data on induced abortions from the Alan Guttmacher Institute Abortion Provider Survey and data on births from U.S. vital statistics. For the United States in 1980 the probability of a spontaneous abortion is 19 percent, given the presence of induced abortion. Once the effects of spontaneous abortion are discounted, women in 1980 intended to allow 73 percent of their pregnancies to proceed to a live birth. One medical benefit to a population practicing induced abortion is that induced abortions avert some spontaneous abortions, leading to a lower mean gestational duration at the time of spontaneous abortion.

Seasonal variation in adolescent conceptions, induced abortions, and late initiation of prenatal care

The monthly distribution of conceptions among adolescents and the proportion of adolescent pregnancies that are voluntarily terminated by induced abortion by month of conception are the objects of this study. Additionally, seasonal variations in the timing of initiation of prenatal care services by adolescents are investigated. Vital records files of single live births, fetal deaths, and induced terminations of pregnancy to residents in the State of South Carolina, 1979-86, were aggregated to estimate conceptions. There was a significant difference between adolescents and adults in the monthly distribution of conceptions. The peak month of adolescent conceptions coincided with the end of the school year. Pregnancies of adolescents occurring at this time further demonstrated later access of prenatal care services than conceptions occurring at other times of the year, most notably during the school term. These findings suggest that there is considerable opportunity for improving the availability of reproductive health care services for adolescents. The results specifically suggest the potential benefit of increasing adolescent pregnancy prevention efforts prior to high-risk events and increasing the availability of and access to health care and counseling services to adolescents during the school recess months of the summer.

Teenage pregnancy in South Australia, 1986-1988

Teenage pregnancies accounted for 6.0% of confinements and 24.8% of legal abortions in South Australia in 1986-1988. The teenage pregnancy rate has declined by 28.5% since the early 1970s, associated with a 52.6% decline in the confinement rate. The abortion rate rose in the 1970s but fell slightly in the 1980s; nearly half the teenage pregnancies now end in legal abortion: abortion was a more likely pregnancy outcome for younger teenagers and for teenagers resident in metropolitan areas. Compared with women confined in their twenties, confined teenagers were more likely to be single, primigravid and Aboriginal, to have few antenatal visits and to have a medical or obstetric complication during their pregnancy. They were less likely to have an induction of labour or an elective Caesarean section. They had higher frequencies of preterm deliveries (8.9%) and low birth-weight babies (9.3%). The youngest teenagers had the most risk factors and the worst outcomes. In the small group of Aboriginal teenagers aged 16 years and under, about a third of the babies were low birth-weight or premature and one in 12 babies was a perinatal death. Comparison of singleton pregnancies of teenagers with women in their twenties all of whom were single, Caucasian and primigravid, with 7 or more antenatal visits, showed similarity in outcomes. This suggests that being teenage is not in itself a risk factor. Continued support and extension of teenage counselling and antenatal care services is essential.

Exposure, susceptibility, and breast cancer risk: a hypothesis regarding exogenous carcinogens, breast tissue development, and social gradients, including black/white differences, in breast cancer incidence

At present, known risk factors account for only one-third of breast cancer cases diagnosed in the United States. They explain an even smaller fraction of the ten-fold variation in international breast cancer incidence rates. The low population-attributable risk of these identified risk factors, plus the existence of phenomena that cannot be easily explained by current etiologic hypotheses (such as the higher rate of breast cancer among black as compared to white women under age 40 within the United States), suggests that unidentified risk factors contribute substantially to breast cancer causation. This paper summarizes evidence to propose that two socially-conditioned factors determine a society's breast cancer incidence and its social gradients in risk: 1) the extent of exposure to exogenous carcinogens, and 2) breast tissue susceptibility to these exposures. It is further hypothesized that breast tissue susceptibility is inversely related to breast tissue differentiation, and that socially-mediated reproductive patterns (involving both early-terminated and full-term pregnancies) affect susceptibility both by altering (via hormonally-mediated mechanisms) the number and ratio of undifferentiated and differentiated cells, and by stimulating the growth of initiated and transformed cells. This view is presented in contrast to hypotheses that propose exposure to endogenous hormones as the major determinant of breast cancer risk.