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Endocrine basis for the initiation, maintenance and termination of pregnancy in humans.

Channels of hormonal communication between the embryo and the mother are established early in the conceptual process. The preimplantation embryo exerts local uterine and systemic effects on the maternal organism to provide a suitable environment for embryonic development, to enable the development of a receptive endometrium for implantation, and to maintain corpus luteum function. In primates, implantation can be induced with progesterone alone if the proliferative effects of estrogens on the endometrium have already been achieved; estrogens may have a priming effect for progesterone on the endometrium, but it is not obligatory for implantation. Progesterone secretion from the corpus luteum is essential for the maintenance of early pregnancy until the placenta takes over the major role of steroidogenesis. This luteo-placental shift is completed at about the 50th day of human gestation. Withdrawal of progesterone effects by the administration of the competitive progesterone antagonist, RU 486, within 24 days after conception will terminate 85% of human pregnancies. Other nonsteroidal functions of the corpus luteum have been recently suggested. Relaxin and prorenin are peptides secreted by corpus luteum of pregnancy but their role remains putative at the present time.

Abortion, Spontaneous

Pregnancy outcome in Norway after Chernobyl.

Pregnancy outcome has been studied in terms of legal abortions, early spontaneous abortions and total number of pregnancies (in an ad hoc study covering 6 counties) as well as various perinatal health problems (on the basis of routinely recorded data for epidemiological surveillance from the Medical Birth Registry of Norway). Apparently, no effects were observed in terms of an increased occurrence of legal abortions, while spontaneous abortions increased from 7.2% of all pregnancies during the last 12 months before the accident to 8.3% after the accident [corrected]. At the same time, the total number of pregnancies somewhat decreased. Based on monthly measurements in each municipality of external and internal (food-based) doses, dose-response associations were assessed for a number of perinatal health problems. No associations were observed.

Abortion, Legal

Incidence of legal abortions and congenital abnormalities in Hungary.

The annual and monthly distributions of congenital abnormalities and pregnancy outcomes as confounding factors were evaluated in Hungary in reflection of the accident at the Chernobyl reactor. The different congenital abnormality entities and the components of fetal radiation syndrome did not show a higher rate after the Chernobyl accident in the data-set of the Hungarian Congenital Abnormality Registry. Among confounding factors, the rate of induced abortions did not increase after the Chernobyl accident in Hungary. In the 9th month after the peak of public concern (May and June, 1986) the rate of livebirths decreased. Three indicator conditions: 15 sentinel anomalies as indicators of germinal dominant gene mutations, Down syndrome as an indicator of germinal numerical and structural chromosomal mutations, and unidentified multiple congenital abnormalities as indicators of germinal dominant gene and chromosomal mutations were selected from the material of the Hungarian Congenital Abnormality Registry. Diagnoses were checked, familial and sporadic cases were separated and only the sporadic cases were evaluated. The analysis of indicator conditions did not reveal any measurable germinal mutagenic effect of the Chernobyl accident in Hungary.

Abnormalities, Radiation-Induced

Breastfeeding: a natural method for child spacing.

Lactational amenorrhea plays an important role in child spacing. Recent research has led to a consensus regarding the status of lactational amenorrhea as a method of family planning. This is currently referred to as the lactational amenorrhea method. Research priorities were to field test the lactational amenorrhea method and define the factors that influence lactational amenorrhea and the interface between the lactational amenorrhea method and other family planning methods.

Amenorrhea

The influence of the post-Chernobyl fallout on birth defects and abortion rates in Austria.

OBJECTIVES: We analyzed the influence of the radioactive fallout after the Chernobyl disaster on the rate and regional distribution of birth defects and abortion rates in southern Austria. STUDY DESIGN: During 1985 to 1989 a total of 66,743 births was monitored. Twelve sources provided data on 1695 cases of birth defects, 1579 of which were suitable for analysis. All cases were analyzed in terms of their calculated conception date and divided into three main groups according to their vulnerable phase of embryogenesis, spermatogenesis, and oogenesis. To study possible regional changes, the findings were plotted in 17 political subdistricts. The overall abortion rate and the counseling frequency at termination clinics was determined. RESULTS: No significant changes in the incidence of birth defects, abortion rate, or counseling rate at pregnancy termination clinics were observed. CONCLUSIONS: Assessing the teratologic potential of low-dose radiation is difficult and requires adequate grouping of birth defects, sufficient baseline data, and highly reliable registries.

Abortion, Induced

Contraceptive use projections: 1990 to 2010.

Factors that will affect both contraceptive use and choice of method during the next 20 years are reviewed. Two factors are predictable: the changing age distribution of women and the revised upper-age limits for oral contraceptive use, with the effect of the latter as yet unknown. Less predictable factors include the number of women in each age group at risk for pregnancy, the effects of delayed childbearing and sterilization, and the impact of new contraceptive methods. Unpredictable factors include adverse publicity about oral contraceptives and breast cancer, concern about sexually transmitted diseases and acquired immunodeficiency syndrome, and changes in the availability of legal abortion. Numbers of women using oral contraception, other reversible methods, sterilization, and no method are projected from 1990 to 2010 under the assumption that use patterns in each age group resemble those observed in 1988. We conclude that discrepancies between projections of contraceptive use and fact are likely to occur because of the unpredictable nature of these few important variables.

Abortion, Legal

Characteristics of women undergoing induced abortion: results of a case-control study from Northern Italy.

In order to identify subgroups of women at elevated risk of induced abortion, personal characteristics and habits, selected medical histories and contraceptive practices of 873 women undergoing legal abortion in various areas of Northern Italy were compared with those of 504 control subjects identified in family planning clinics of the same hospitals or area health authorities. When age was allowed for, the risk of induced abortion was not strongly influenced by marital status, education or other indicators of social class. However, women who were employed, independently from the type of occupation, showed markedly lower abortion risks than housewives. Among various indicators of sexual habits investigated, the strongest determinant of legal abortion was the frequency of sexual intercourses over the previous six months, women with less frequent intercourses showing a markedly elevated risk estimate (RR = 2.82). Induced abortion was less frequent among ex-smokers and more frequent in heavy smokers, but was not appreciably influenced by several other indicators of lifestyle habits and history of gynaecological or psychiatric complaints. The risk of abortion was not influenced by the number of livebirths, but was lower for women with later age at first birth. Less than 5% of case and control subjects reported more than two previous induced abortions, thus indicating that abortion is more of an "accidental" event rather than a widespread contraceptive practice. However, over three-quarters of abortions occurred in women reporting no contraception at all or coitus interruptus, thus underlining the scope for family planning education in this population.

Abortion, Legal

Are there adverse effects of periconceptional spermicide use?

Recent studies have suggested that spermicide exposure around conception may cause congenital malformations, reduced birth weight, or spontaneous abortion. This large, prospective study examined the risk for multiple malformation, patterns of malformations, low birth weight, preterm delivery, and spontaneous abortion in infants whose mothers used spermicides only before or after their last menstrual period, compared with a control group using other contraceptive methods. The multiple malformation rates in women using spermicides only before or after their last menstrual period were 3.8 and 4.8 per thousand, respectively. For the control groups, the corresponding rates were 5.4 and 6.4 (not significant). No pattern of malformations was found in spermicide-exposed infants. The risk of preterm delivery, the risk for producing a low-birth-weight (less than 2500 gm) infant, and the risk of spontaneous abortion were no higher in women exposed to spermicides than in women using other methods of contraception. This study finds no evidence that spermicide exposure around the time of conception is dangerous to the fetus.

Abnormalities, Drug-Induced

The effect of pregnancy termination on future reproduction.

A variety of conditions have been anecdotally ascribed to induced abortion, including subsequent reproductive complications. Since most women obtaining induced abortions are at the beginning of their reproductive life, the effect of induced abortion on subsequent reproduction becomes a very significant one. Our review of the literature confirms findings reported previously. First, except in the case where an infection complicates induced abortion, there is no evidence of an association between induced abortion and secondary infertility or ectopic pregnancy. Second, the risk of midtrimester abortion, premature delivery and low birthweight in women whose first pregnancy is terminated by vacuum aspiration is not higher than that in women in their first pregnancy or women in their second pregnancy whose first pregnancy was carried to term. However, the risk of having a premature delivery or a low birthweight baby tends to be higher (but not significantly) among women whose first pregnancy is terminated by induced abortion when compared with women in their second pregnancy than when compared with women in their first pregnancy. This suggests that an induced abortion does not protect a women against the known risk of low birthweight for first-born offspring. Finally, women whose pregnancy is terminated by dilatation and evacuation may have an increased risk of subsequent premature delivery and a low birthweight baby. Very little has been published and no conclusions can be made regarding the effects of instillation procedures and repeat abortions on future reproduction. In conclusion, except for the association between pregnancies following dilatation and evacuation procedures and premature delivery and low birthweight, no significantly increased risk of adverse reproductive health has been observed following induced abortion.

Abortion, Induced

Risk factors for adenocarcinoma of the cervix: a case-control study.

To assess risk factors for cervical adenocarcinoma data were collected in a case-control study of 39 cases and 409 controls conducted in the greater Milan area. Questions were asked about personal characteristics and habits, gynaecologic and obstetric data, history of lifetime use of oral contraceptives and other female hormones, and general indicators of sexual habits (age at first intercourse and total number of sexual partners). The relative risk of cervical adenocarcinoma increased with number of births and abortions, early age at first birth and early age at first intercourse. These estimates did not materially change after adjustment for the potential reciprocal confounding effect. Further, there was a positive association with overweight, but an apparent association with lower education was not significant. No relationship emerged with oral contraceptive use. Thus, despite the similarities with the epidemiology of squamous cell cancer, reproductive patterns and other factors related to the risk of endometrial cancer (i.e., overweight) seem to play an important role in the risk of adenocarcinoma of cervix uteri.

Abortion, Spontaneous

Risk of late first and second trimester miscarriage after induced abortion.

A cohort of 3110 women anticipating delivery were interviewed after their first prenatal visit at private obstetric practices and HMOs in Connecticut. In all 19.57% reported a prior induced abortion. The research participants were followed to determine whether the pregnancy was miscarried or delivered. In all, 2.19% miscarried in the late first or second trimester. The association of a prior induced abortion on risk for late miscarriage was analyzed by pregnancy history. Women who aborted their first pregnancy had no increased risk (RR = 0.56, 95% CI = 0.16, 1.92) of miscarriage compared with women pregnant for the first time, or compared with women experiencing their second pregnancy after delivering the first (RR = 0.69, 95% CI = 0.18, 2.60). No evidence was found for an increased risk of multiple induced abortion on subsequent miscarriage.

Abortion, Induced

Preference for male children and contraceptive use in Taiwan.

Taiwan has an active family-planning program. Yet the preference for sons is deeply ingrained in the Chinese culture and may discourage women from limiting their family size if they feel they have too few sons. In this study, research problems concerned the relationships between women's stated preferences for the sex of their children, their perceptions of their in-laws' preferences for the number and sex of their children, and their use of birth control and choice of birth control methods. It was found that few women verbalized a preference for the sex of children, but the number of boys already in the family was related to the reliability of contraceptive method used later and to the willingness to consider abortion if pregnancy occurred. The desired number and occurrence of additional children related to women's perceptions of their in-laws' preferences for boys. The perception of in-laws' preferences for girls either related negatively or was not significant.

Adult