Maternal hormone therapy and congenital heart disease

Noninherited risk factors and congenital cardiovascular defects: current knowledge: a scientific statement from the American Heart Association Council on Cardiovascular Disease in the Young: endorsed by the American Academy of Pediatrics

Prevention of congenital cardiovascular defects has been hampered by a lack of information about modifiable risk factors for abnormalities in cardiac development. Over the past decade, there have been major breakthroughs in the understanding of inherited causes of congenital heart disease, including the identification of specific genetic abnormalities for some types of malformations. Although relatively less information has been available on noninherited modifiable factors that may have an adverse effect on the fetal heart, there is a growing body of epidemiological literature on this topic. This statement summarizes the currently available literature on potential fetal exposures that might alter risk for cardiovascular defects. Information is summarized for periconceptional multivitamin or folic acid intake, which may reduce the risk of cardiac disease in the fetus, and for additional types of potential exposures that may increase the risk, including maternal illnesses, maternal therapeutic and nontherapeutic drug exposures, environmental exposures, and paternal exposures. Information is highlighted regarding definitive risk factors such as maternal rubella; phenylketonuria; pregestational diabetes; exposure to thalidomide, vitamin A cogeners, or retinoids; and indomethacin tocolysis. Caveats regarding interpretation of possible exposure-outcome relationships from case-control studies are given because this type of study has provided most of the available information. Guidelines for prospective parents that could reduce the likelihood that their child will have a major cardiac malformation are given. Issues related to pregnancy monitoring are discussed. Knowledge gaps and future sources of new information on risk factors are described.

Evaluating emerging issues in epidemiology

Industry and government institutions need a credible approach for evaluating and responding to emerging public health issues. Representatives of industry, government, and academia met under the auspices of the International Life Sciences Institute's Health and Environmental Sciences Institute (HESI) to develop successful strategies for dealing with emerging issues based on historical case studies. The case studies chosen for evaluation were (1) tampon use and toxic shock syndrome; (2) hazardous waste and childhood cancer risk in Toms River, New Jersey; (3) fenfluramine and phentermine use and valvular heart disease; (4) silicone breast implants and cancer and auto-immune disease; and (5) progestational drugs and birth defects. We identified eight lessons from these case studies. Foremost, we recommend that public and private institutions not defer action until an issue is scientifically resolved and stress that cooperation among issue stakeholders is critical for effective issue resolution. We suggest establishing a research program as an effective way to assure that good science is included in resolution of the issue. We further recommend frequent and timely communication with all stakeholders, and the development of research approaches to fill gaps when the scientific data on an issue are limited.

Barriers to contraceptive use in product labeling and practice guidelines

Many contraceptives are encumbered with potentially unnecessary restrictions on their use. Indeed, fear of side effects, fostered by alarmist labeling, is a leading reason that women do not use contraceptives. In the United States, hormonal methods currently require a prescription, although research suggests that women can adequately screen themselves for contraindications, manage side effects, and determine an appropriate initiation date, leaving little need for routine direct physician involvement. Sizing, spermicidal use, and length-of-wear limits burden users of cervical barriers and may be unnecessary. Despite recent changes in the labeling of intrauterine devices, clinicians commonly restrict use of this method and in some countries may limit the types of providers authorized to insert them. Although in some cases additional research is necessary, existing data indicate that evidence-based demedicalization of contraceptive provision could reduce costs and improve access.

“Natural” progesterone: information on fetal effects

BACKGROUND

A variety of progestational agents have been used therapeutically and evaluated for adverse effects over the last 50 years. However, progesterone itself has come into use as a therapeutic agent only recently with the development of an orally bioavailable "micronized" preparation.

METHODS

The current review examines progesterone adverse effects as identified in the larger literature on the toxicity of progestational agents and pharmacokinetics.

RESULTS

Progesterone has cytoplasmic and membrane receptors in a variety of reproductive and nonreproductive tissues including the brain and is a potent inhibitor of GnRH. Limited information is available on progesterone receptors and actions in the fetus. Concern about exogenous progestagen effects on fetal reproductive tract development have led to considerable human research over the years, but this literature review demonstrates that contemporary developmental toxicology research on progesterone is lacking.

CONCLUSIONS

Progesterone is a potent, multi-faceted endocrine agent with an expanding therapeutic profile and a minimal scientific database for evaluating safe use during pregnancy.

Nongenital malformations following exposure to progestational drugs: The last chapter of an erroneous allegation

In the late 1960s and 1970s, a number of epidemiological studies were published indicating that pregnant women who were exposed to an array of sex steroids delivered infants with an increased incidence of nongenital congenital malformations. Because of these publications, the Food and Drug Administration (FDA), in conjunction with various pharmaceutical companies, labeled the therapeutic exposure of progestational drugs and contraceptives in pregnant women as a risk factor for limb-reduction defects (LRDs) and congenital heart defects (CHDs). Subsequently there was a rapid decrease in the exposure of pregnant women to these drugs and the initiation of numerous lawsuits alleging that a particular progestational drug was responsible for a child's nongenital congenital malformation. Wilson and Brent (1981) published an article indicating that epidemiological and animal studies of these drugs, and basic science did not support the package insert's warnings. Many new and previous animal and epidemiological studies did not support the FDA box warning. In 1987 the FDA held a hearing in which the FDA, the Teratology Society, the Centers for Disease Control and Prevention, the American College of Obstetrics and Gynecology, and other organizations supported the position that progestational agents did not result in nongenital malformations. An editorial appeared in Teratology congratulating the FDA for removing the warning label on oral contraceptives regarding nongenital malformations. In 1999 the FDA published new wording for package inserts that removed warnings for nongenital malformations for all progestational agents. In spite of the recent changes in the package inserts, lawsuits have alleged that progestational drugs cause nongenital malformations. It took 22 years from the time a box warning was required by the FDA until the warnings were removed in 1999. The 1999 FDA publication, which is a scholarly and objective document, should put an end to 2 decades of concern and anxiety for pregnant women or women of reproductive age. Could scientists, the pharmaceutical companies, or the FDA have prevented the mislabeling of progestational drugs with regard to their teratogenic risks? Was the epidemiological or teratology community at fault because they did not critique and respond to the early publications? Did the FDA act too slowly? The epidemiologic analyses, animal studies, and basic science principles have been reviewed, and it is obvious that clinically utilized progestational drugs do not cause nongenital malformations (i.e., LRDs and CHDs).

Cardiovascular birth defects and prenatal exposure to female sex hormones: a reevaluation of data reanalysis from a large prospective study

In data of the U.S. Collaborative Perinatal Study (CPS), the Drug Epidemiology Unit (DEU) reported a relative risk of about 2.3 between maternal female sex hormone exposure during months 1 to 4 of pregnancy and cardiovascular malformation in infants (Heinonen et al., '77a N. Engl. J. Med., 296:67-70). Wiseman and Dodds-Smith ('84, Teratology, 30:359-370) reexamined the original CPS data and found the DEU had made some errors in classification of exposure and disease. Also they challenged the classification of cases as "exposed" in those born to mothers who received the compounds outside the day 19 to 50 window of cardiovascular embryogenesis. Wiseman and Dodds-Smith stated that their reanalysis "clearly showed that there was [in the data used by the DEU] no statistically significant association between exposure in the critical organogenic period of pregnancy and cardiac malformation in offspring." They did not undertake any statistical analysis, but their reanalysis resulted in a wide-spread nonacceptance of the association reported by the DEU. The study reported here reclassified the cases of the original DEU study in accord with the implications of the Wiseman and Dodds-Smith reanalysis of exposure and disease. After this reclassification, an effect magnitude measure of association, the relative risk rose from 2.33 to 2.48 and remained nominally significant statistically at the .05 level. Thus, if anything, the quantitative consequences of the Wiseman and Dodds-Smith review of the data, when applied in an unbiased manner, result in an increase in the measure of effect.(ABSTRACT TRUNCATED AT 250 WORDS)

A case-control study of major congenital heart defects in Sweden--1981-1986

This paper reports the results of a case-control study of major congenital heart defects (CHD) in Sweden. During the period 1981-1986, 1,324 such cases were identified and 2,648 controls were selected. Some common maternal characteristics and exposures were studied using information from prospectively collected data. Possible associations with CHD were found for previous perinatal death, maternal diabetes, epilepsy, hydramnios and disproportion between fetus and pelvis. More specific associations were observed between previous spontaneous abortion, epilepsy, hydramnios and truncus anomalies and between diabetes and septal anomalies. However, no associations were found with involuntary childlessness, contraceptive use, or smoking.

Congenital heart disease in the offspring and maternal habits and home exposures during pregnancy

To test the effect of maternal habits and home exposures during early pregnancy on the occurrence of congenital heart disease in the offspring, 406 cases and 756 controls were studied. The cases included all cardiovascular malformations detected in Finland during 1982-1983, while the healthy controls were randomly selected from all babies born during the same period. Case and control mothers were interviewed after delivery using a structured and pre-tested questionnaire. Maternal overall drug consumption during the first trimester was as prevalent among case mothers (13.3%) as controls (14.6%). Neither was the risk of congenital heart disease associated with maternal use of contraceptive pills, salicylates, diazepam, or sweetening agents separately. Maternal exposures to disinfectants, dyes, lacquers, paints, pesticides, or glues at home were equally prevalent in case and control groups. Several earlier miscarriages was a predictor of an infant born with congenital heart disease (OR = 2.7, CI95 = 1.4-5.3). Maternal ultrasound examination was performed during the first 16 weeks of pregnancy more often among the case group (28.3%) than among the control group (22.0%). However, the association between ultrasound examination and the risk of congenital heart disease in the offspring was not statistically significant (OR = 1.2, 95% confidence interval 0.9-1.7) when adjusted for confounding factors such as the threat of miscarriage in logistic regression analysis. It is concluded that maternal ultrasound examination, intake of some common drugs, and exposure to a number of environmental factors at home during early pregnancy are probably not harmful for the developing fetal heart.

Cardiovascular birth defects and prenatal exposure to female sex hormones: a reevaluation of data reanalysis from a large prospective study

In data of the U.S. Collaborative Prenatal Study (CPS), the Drug Epidemiology Unit (DEU) reported a relative risk of about 2.3 between maternal female sex hormone exposure during months 1 to 4 of pregnancy and cardiovascular malformation in infants (Heinonen et al., '77a N. Engl. J. Med., 296:67-70). Wiseman and Dodds-Smith ('84) reexamined the original CPS data and found the DEU had made errors in classification of exposure and disease of some cases. Also they challenged the classification of cases as "exposed" in those born to mothers who received the compounds outside the day 19 to 50 window of cardiovascular embryogenesis. Wiseman and Dodds-Smith stated that their reanalysis "clearly showed that there was [in the data used by the DEU] no statistically significant association between exposure in the critical organogenic period of pregnancy and cardiac malformation in offspring." They did not undertake any statistical analysis, but their reanalysis resulted in a widespread nonacceptance of the association reported by the DEU. The study reported here reclassified the cases of the original DEU study in accord with the implications of the Wiseman and Dodds-Smith reanalysis of exposure and disease. After this reclassification, an effect magnitude measure of association, the relative risk rose from 2.33 to 2.48 and remained nominally significant statistically at the .05 level. Thus, if anything, the quantitative consequences of the Wiseman and Dodds-Smith review of the data, when applied in an unbiased manner, result in an increase in the measure of effect.(ABSTRACT TRUNCATED AT 250 WORDS)

Congenital cardiovascular malformations: questions on inheritance. Baltimore-Washington Infant Study Group

The Baltimore-Washington Infant Study, an epidemiologic investigation of congenital heart disease, searches for genetic and environmental risk factors. Among 2,102 infants with heart disease, 17.5% had a noncardiac abnormality of chromosomal or genetic origin, whereas among 2,328 control infants, only 0.7% had a genetic abnormality. Familial cardiovascular malformations encountered can be grouped into five distinct etiologic mechanisms. Single gene effects may be responsible for the specific histologic and biochemical changes in familial atrial septal defect with conduction disturbance and also in idiopathic ventricular hypertrophy. Left heart lesions showed familial concordance by the presumed morphogenetic mechanism of abnormal embryonic blood flow with phenotypes of varying severity. Pulmonary stenosis appeared with familial heritable disorders, as well as a partially concordant lesion with tetralogy of Fallot. Ventricular septal defect with transposition of the great arteries (one sibling pair) and with truncus arteriosus (two sibling pairs) indicate forme fruste expression of conotruncal defects. Endocardial cushion defect occurred with and without Down's syndrome in members of three families, suggesting inheritance of a defect affecting cellular migration. Heritable blood coagulopathies occurred in case families and not in control families. The associated of hemophilia and transposition, observed also by others, is extremely unlikely by chance and suggests genetic errors of endothelial cell function. The description of specific families from a population-based study emphasizes biologic questions on the nature of the inheritance of cardiovascular malformations.

Scientific standards and the design of case-control research

A new controversy has emerged over the results of a case-control study alleging a causal relationship between certain non-steroidal anti-inflammatory agents (NSAIAs) and the risks of agranulocytosis and aplastic anemia. After describing the methods and results of the International Agranulocytosis and Aplastic Anemia (IAAA) study, we review the distinctive methodologic challenges of this study and the requirements for avoiding bias, and then reconcile the study results with the principles of case-control design. As a result of our analysis, we believe that the IAAA study's most important and reliable finding is its documentation of the infrequent occurrences of aplastic anemia and agranulocytosis with analgesic use. In contrast, a causal association between NSAIAs and blood dyscrasias has not been suitably established, and may well have resulted from several distinctive sources of bias. These include the effects of diagnostic-suspicion bias in case determination, of exclusion bias in choosing controls, of recall bias in determining exposure, and of publicity bias in both case selection and ascertainment of exposure. These problems could have been avoided and a more valid result obtained with closer attention to the experimental paradigm for case-control research.

The causes and underlying developmental mechanisms of congenital cardiovascular malformations: a critical review

Cardiovascular malformations are the second most common type of birth defect, occurring in 5-8/1,000 livebirths with a still higher prevalence among stillborn infants and spontaneously aborted embryos and fetuses. Dealing effectively with the high frequency of heart defects means reducing the incidence of cardiac malformations in the world. In this paper we cite some of the genetic and environmental risk factors associated with congenital cardiovascular malformations, describe the putative biochemical nature of the genetic predisposition relative to environmentally induced teratogenesis, and either support or discourage the use of available methods as strategies in preventing cardiovascular anomalies.

Congenital malformations among offspring exposed in utero to progestins, Olmsted County, Minnesota, 1936-1974

Comparison of a cohort of 988 offspring exposed in utero to exogenous progestins with a matched cohort of unexposed offspring did not result in detection of an association of congenital anomalies with exposure. The conclusions are based primarily on outcomes of pregnancy with exposure to progesterone and 17 alpha-hydroxyprogesterone caproate, and may not apply to androgenic progestins. Offspring exposed to combinations of progestins and estrogens were excluded from this study and may have a different distribution of anomalies.

Cardiovascular birth defects and antenatal exposure to female sex hormones: a reevaluation of some base data

A re-evaluation of the base data as reported by Heinonen et al. from the Drug Epidemiology Unit of the Boston Collaborative Perinatal Project (CPP) was undertaken in order to examine particularly three matters which were not fully considered in the publication. These were, first, the timing of administration of sex hormones during the index pregnancy, which is relevant to determining whether any statistical association reported between sex hormone exposure and malformations could be causal; second, the incidence of serious maternal vaginal bleeding in early pregnancy, which could be an indication of threatened abortion, which in turn is associated with an increased malformation rate, and in addition is an indication for sex hormone administration; and third, the incidence of malformations or other adverse outcome in previous pregnancies, which, if present, might play a material role in the risk of malformation in the index pregnancy. Examination of the records of the 19 cases described by Heinonen et al. as hormone-exposed/cardiac-malformed revealed that no preparation containing hormone was administered in two patients, that five cases were given hormones too late in the index pregnancy to have any effect on cardiac organogenesis (which by general consensus begins on day 19 and ends at the latest on day 50 of gestation), that two cases were given hormones too early and two cases had Down's Syndrome. Thus eight children were exposed to hormones during the critical period of cardiac organogenesis, out of 17 actual hormone takers (47%). The description of vaginal bleeding did not allow any conclusions regarding differential rates of threatened abortion. It was found that the incidence of major malformations was 17% in the index group and 4% in the non-malformed group. This suggests that the hormone-exposed patients who gave rise to children with cardiac malformations were a highly selected group. The re-evaluation therefore reveals that the incidence of exposure to sex hormones during the critical period of cardiac organogenesis was not significantly different statistically in those women whose children had cardiac lesions as compared to those without such lesions. It is suggested that the result of this re-evaluation should direct the attention of epidemiologists to the quality of their base data. Re-examination of the base data of the Boston CPP does not support their reported association between the exposure to female sex hormones during pregnancy and the occurrence of cardiac malformations.

Prospective study of suspected associations between certain drugs administered during early pregnancy and congenital malformations

From 1964 to 1976, a cohort study was performed in West Germany to study the possible influence of various factors on pregnancy and child development. Results of the evaluation of 13,643 pregnancies are given with respect to possible teratogenetic effects of antiemetic drugs and sex hormones administered in early pregnancy. There was no evidence of an increased risk of major malformations following the intake of certain antiemetic drugs and progesterone. Also, the use of a hormonal pregnancy test was not significantly associated with an increase of major malformations.

World survey of the common cardiac malformations: developmental error or genetic variant?

The common cardiac malformations are prevalent throughout the world, in countries of high technology and among the primitive races. These same malformations were described 200 years ago, ectopia cordis 5,000 years ago. Their recent increase is directly related to the advent of cardiac treatment. Most cardiac malformations known to man occur in the dog. The prevalence rate of these malformations is the same in the dog and in man (5-8/1,000). Several of the malformations are heritable in specific breeds of dogs, one in rabbits, another in rats. These malformations occur in various animals that cannot interbreed. Hence the deoxyribonucleic acid (DNA) that codes these malformations must lie in that portion of the DNA common to all mammals. This suggests that these malformations occurred during the evolution of the Mammalia. Mammals evolved from reptiles, animals with hearts of various structures for the separation of arterial and venous blood. Although the "normal" heart is the most compatible with mammalian life and hence the most common, some mammals may have evolved with a heart with different structures for the separation of arterial and venous blood. Some of these hearts have persisted. These primeval hearts we call cardiac malformations of the cyanotic group. Malformations that apparently are arrests in the development of the normal heart (patent ductus arteriosus, atrioventricular canal) may represent stages in the evolution of the "normal" heart. Although teratogens and mutagens do exist, the author conceives of congenital cardiac malformations not as arrests or errors in the development of a "normal" heart but as genetic variants.