Limb Reduction Defects Research Articles

PBX, MEIS, and IGF-I are potential mediators of retinoic acid-induced proximodistal limb reduction defects.

Phocomelia, which is primarily due to a disruption in the proximodistal axis, is found in virtually all mouse embryos exposed to high doses of retinoic acid (RA) on 11 days post coitum (dpc). To identify genes that potentially mediate the effects of retinoic acid (RA) on limb development, we have examined the expression of 9,000 clones from the IMAGE consortium by microarray analysis of RNA isolated from 11 dpc mouse forelimbs exposed to RA or vehicle for 6 hr. Eight genes that demonstrated altered expression were chosen for further study of their mRNA levels using RT-PCR. Protein levels were determined by Western blot analysis. Of the 9,000 genes examined in the microarray, approximately 111 demonstrated altered expression (33 known genes and 78 ESTs). Of the eight known genes chosen for further study using RT-PCR, four mRNAs (PBX1a, PBX1b, IGF-Ia, and IGF-Ib) demonstrated consistent elevation ( approximately 3-fold) in their levels after RA treatment in both the forelimbs and hindlimbs as early as 3 hr after RA treatment. In addition to the two PBX1 isoforms, the mRNA level of the other two subtypes (PBX2 and PBX3) and the level of PBX1/2/3 protein were also found to be elevated in limb buds after RA treatment. Finally, we examined the expression of MEIS1, MEIS2, and MEIS3 because these proteins are necessary for PBX nuclear localization. The mRNA level of all three subtypes of MEIS were elevated approximately three- to four-fold in both the forelimbs and hindlimbs after RA treatment. Because both PBX and MEIS (and their orthologs) are believed to be involved in the control of proximodistal axis formation in mouse and fly limbs and IGFs in the development of limbs, we suggest that increases in PBX, MEIS and IGF-1 mRNA levels may contribute to proximodistal limb reduction defects caused by teratogenic doses of RA.

Clinical proceduress in prenatal diagnosis

The prenatal diagnosis of fetal genetic disease has become a routine part of obstetric care. Pregnancies at risk are identified by a number of factors, including maternal age, positive serum screening, a history of a previous affected child, a parental chromosome rearrangement or an ultrasound-identified anomaly. Invasive diagnostic testing can be performed in the first trimester by chorionic villus sampling or in the second trimester by amniocentesis. Both procedures are safe, with an equivalent 0·5% risk of procedure-induced pregnancy loss. When performed prior to the routine sampling window of 15 weeks, amniocentesis may increase the risk of talipes equinovarus, the highest risk being encountered prior to 13 weeks' gestation. When chorionic villus sampling is performed prior to 9 weeks' gestation, there may be an increased risk of limb reduction defects. The laboratory analysis of both procedures is reliable. Chorionic villus sampling has a 1–2% incidence of confined placental mosaicism, requiring additional evaluation in some cases.

Further evidence for the role of free radicals in the limb teratogenicity of L-NAME.

L-NAME (N(G)-nitro-(L)-arginine methyl ester), a nitric oxide synthase inhibitor, causes severe limb reduction malformations when gravid rats are treated intraperitoneally on gd-17. Hemorrhages, appearing within hours of L-NAME administration, and defects at term can be significantly reduced by co-treatment with PBN (alpha-phenyl-N-t-butylnitrone), a spin trap antioxidant. We have proposed that limb defects result from ischemia-reperfusion injury. We examine the role of xanthine oxidase and ROS formation in the limb effects of L-NAME. Gravidas were treated with L-NAME (50 mg/kg) in the presence or absence of allopurinol, a xanthine oxidase inhibitor. Spatial patterns of limb hemorrhage were determined promptly and at term as was digit length at the latter interval. Xanthine oxidase activities were assayed in control and treated limbs with and without allopurinol co-treatment. Allopurinol significantly reduced hemorrhage severity in a dose-responsive fashion when fetuses were examined at term. Higher doses of allopurinol significantly preserved digit length. Xanthine oxidase activities in fetal limb were significantly increased by L-NAME treatment whereas co-treatment with allopurinol restored activities to near-control levels. These findings support the role of excess reactive oxygen species (ROS) formation in L-NAME-induced limb reduction. We propose that nitric oxide (NO) depletion by L-NAME interferes with vascular integrity, and causes vasoconstriction. Resultant hypoxia stimulates superoxide formation and nitric oxide formation catalyzed by the inducible isoform of nitric oxide synthase. The reduction products of superoxide or the products of its reaction with nitric oxide oxidize or nitrate endothelial components resulting in limb reduction defects.

Procedural risks versus theology: Chorionic villus sampling for Orthodox Jews at less than 8 weeks' gestation

Objective: According to Orthodox Jewish law, abortion is only permitted before 40 days post conception. This evaluation was performed to determine the feasibility and safety of performing chorionic villus sampling (CVS) at 7 to 8 weeks' gestation so that genetic results would be useful for these patients. Study Design: We evaluated a sequential series of 82 Orthodox Jewish patients who chose CVS at <63 days' gestation. Outcome measures included procedure success rates, laboratory success rates, pregnancy outcomes, and complications. Results: CVS was successful in all cases. Ninety-one percent were performed transcervically, with 30% requiring 2 or more insertions. Abnormal results were found in 16 (20%). Of 61 cases with normal genetic and ultrasound results, spontaneous losses at less than 28 weeks occurred in 3 (5%). These rates are higher than the 2.3% loss rate and the 1.2% multiple insertion rate seen at our center when sampling is performed at the usual gestational ages of 10 to 12 weeks. One baby had a severe limb reduction defect (1.6%). Conclusion: In very experienced hands, CVS can be safely and reliably performed at very early gestational ages. The ability to obtain an early diagnosis may be associated with increased but acceptable complication rates, including a 1% to 2% risk of limb reduction defects. There are patients for whom the usual paradigms do not suffice, and obtaining an early disgnosis provides them the opportunity to trade increased risks for reproductive choice. The ethical issues are complex, but such decisions can be supported by extensive and detailed informed consent. (Am J Obstet Gynecol 2002;186:1133-6)

Involvement of mitochondria and other free radical sources in normal and abnormal fetal development.

Shepard and Mackler have documented quantitative increases in mitochondrial cristae between gestational days 10 and 14 in rats accompanied by decreased glucose utilization and increased NADH oxidase activity. Findings show a shift from glycolytic to oxidative metabolism starting at around the time of implantation. Exposure to many substances that cause transient uteroplacental hypoperfusion, including cocaine, phenytoin, calcium channel blockers, and nitric oxide synthase (NOS) inhibitors, induce limb and central nervous system (CNS) malformations while sparing the heart. We have reported that isolated electron transport particles prepared from sensitive tissues show reduced NADH oxidase activities compared with insensitive heart. They also have significantly greater superoxide formation in association with significantly reduced superoxide dismutase activities. NOS inhibitors induce severe limb reductions in late gestation. Exposure is associated with hemorrhage and nitrotyrosine (NT) formation shortly after treatment. Hemorrhage, malformations, and NT formation can be significantly reduced by coadministration of PBN, allopurinol, or aminoguanidine. On the basis of these findings, we have proposed a role for the formation of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the genesis of limb reduction defects. It is important to note that limb reduction defects occur in humans ( approximately 0.22/1000) and have been associated with the agents listed above.

5-Aza-2'-deoxycytidine-induced cytotoxicity and limb reduction defects in the mouse.

5-Aza-2'-deoxycytidine (dAZA), causes hindlimb phocomelia in CD-1 mice. Studies in our laboratory have examined the hypothesis that compound- induced changes in gene expression may uniquely affect hindlimb pattern formation. The present study tests the hypothesis that dAZA causes limb dysplasia by inducing cytotoxicity among rapidly proliferating cells in the limb bud mesenchyme. Pregnant CD-1 mice were given a teratogenic dose of dAZA (i.p.) at different times on GD 10 and fetuses evaluated for skeletal development in both sets of limbs by standard methods. Using general histology and BrdU immunohistochemistry, limb mesenchymal cell death and cell proliferation were then assessed in embryos at various times post dosing, shortly after initial limb bud outgrowth. The effect of dAZA on early limb chondrogenesis was also studied using Northern analysis of scleraxis and Alcian blue staining of whole mount limb buds. Compound related hindlimb defects were not restricted to a specific set of skeletal elements but consisted of a range of temporally related limb anomalies. Modest defects of the radius were observed as well. These results are consistent with a general insult to the limb mesenchyme. Mesenchymal cell death and reduced cell proliferation were also observed in both sets of limbs. The timing and location of these effects indicate a role for cytotoxicity in the etiology of dAZA induced limb defects. These effects also agree with the greater teratogenicity of dAZA in the hindlimb because they were more pronounced in that limb. The expression of scleraxis, a marker of early chondrogenesis, was reduced 12 hr after dAZA exposure, a time coincident with maximal cell death, as was the subsequent emergence of Alcian blue stained long bone anlagen. These findings support the hypothesis that cytotoxic changes in the limb bud mesenchyme during early limb outgrowth can induce the proximal limb truncations characteristic of phocomelia after dAZA administration.

Stillbirth and neonatal mortality due to congenital anomalies: temporal trends and variation by small area deprivation scores in England and Wales, 1986–96

SummaryWe investigated the variation of stillbirth and neonatal mortality due to congenital anomalies in relation to small‐area measures of deprivation in a population‐based study in England and Wales, 1986–96. We found 10 954 stillbirths and neonatal deaths from all non‐chromosomal and chromosomal anomalies during the study period out of a total of 7 487 007 live and stillbirths. The extended perinatal mortality rate (EPM rate) (defined as babies who were stillborn or died within 28 completed days after birth per 10 000 total live and stillbirths) for all chromosomal and all non‐chromosomal anomalies was 1.5/10 000 and 13.2/10 000, respectively, over the whole period. The rate for non‐chromosomal anomalies halved over the decade while the rate for chromosomal anomalies remained unchanged. The relative risks of EPM for chromosomal and non‐chromosomal anomalies were 0.71 [0.80, 0.95] and 1.17 [95%CI 1.06, 1.30], respectively, in the group of wards with highest deprivation compared with the least deprived group. Increasing gradients of EPM with increasing deprivation were observed for (1) grouped non‐chromosomal anomalies including neural tube defects, all renal and urinary anomalies, all musculoskeletal anomalies, and multiple anomalies, and (2) several specific non‐chromosomal anomalies including anencephaly, limb reduction defects, diaphragm and abdominal wall defects. This study provides strong evidence that increased deprivation is associated with increased EPM due to most non‐chromosomal anomalies; the finding of decreased relative risk for chromosomal anomalies is probably related to differences in maternal age distribution between deprivation groups.

Stillbirth and neonatal mortality due to congenital anomalies: temporal trends and variation by small area deprivation scores in England and Wales, 1986-96.

We investigated the variation of stillbirth and neonatal mortality due to congenital anomalies in relation to small-area measures of deprivation in a population-based study in England and Wales, 1986-96. We found 10 954 stillbirths and neonatal deaths from all non-chromosomal and chromosomal anomalies during the study period out of a total of 7 487 007 live and stillbirths. The extended perinatal mortality rate (EPM rate) (defined as babies who were stillborn or died within 28 completed days after birth per 10 000 total live and stillbirths) for all chromosomal and all non-chromosomal anomalies was 1.5/10 000 and 13.2/10 000, respectively, over the whole period. The rate for non-chromosomal anomalies halved over the decade while the rate for chromosomal anomalies remained unchanged. The relative risks of EPM for chromosomal and non-chromosomal anomalies were 0.71 [0.80, 0.95] and 1.17 [95%CI 1.06, 1.30], respectively, in the group of wards with highest deprivation compared with the least deprived group. Increasing gradients of EPM with increasing deprivation were observed for (1) grouped non-chromosomal anomalies including neural tube defects, all renal and urinary anomalies, all musculoskeletal anomalies, and multiple anomalies, and (2) several specific non-chromosomal anomalies including anencephaly, limb reduction defects, diaphragm and abdominal wall defects. This study provides strong evidence that increased deprivation is associated with increased EPM due to most non-chromosomal anomalies; the finding of decreased relative risk for chromosomal anomalies is probably related to differences in maternal age distribution between deprivation groups.

Limb deficiencies in newborn infants.

The prevalence rate of all types of limb reduction defects in general and those that potentially are caused by vascular disruption in particular is needed to provide a baseline for the evaluation of infants who are exposed in utero to teratogens that cause vascular disruption. The objective of this study was to determine this prevalence rate. All infants with any limb deficiency among 161 252 liveborn and stillborn infants and elective terminations were identified in a hospital-based Active Malformations Surveillance Program in Boston in the years 1972 to 1974 and 1979 to 1994. An extensive search was made to identify infants who were missed by the Surveillance Program; an additional 8 infants (7.3% of total) were identified. The limb reduction defects were classified in 3 ways: 1) by the anatomic location of the defect, that is longitudinal, terminal, intercalary, etc; 2) for infants with absence/hypoplasia of fingers or toes, a tabulation of which digit or digits were affected; and 3) by apparent cause. The prevalence rate for all types of limb deficiency was 0.69/1000. The apparent causes included single mutant genes, familial occurrence, and known syndromes (24%); chromosome abnormalities (6%); teratogens (4%); vascular disruption (35%); and unknown cause (32%). A hospital-based surveillance program can be used to establish the prevalence of limb reduction defects, if ascertainment is extended to include elective terminations for fetal abnormalities. An apparent cause can be established for most limb defects when the clinical findings are used rather than reliance only on the International Classification of Diseases, Ninth Revision, codes of the discharge diagnoses. The prevalence rate of limb reduction defects as a result of presumed vascular disruption was 0.22/1000.

Addressing environmentally caused human birth defects.

1. Robert L. Brent, MD, PhD, DSc* 1. 2. *Distinguished Professor of Pediatrics, Radiology, and Pathology, Anatomy, and Cell Biology; Louis and Bess Stein Professor of Pediatrics; Emeritus Chairman, Department of Pediatrics, Jefferson Medical College, Philadelphia, PA; Head, Laboratory of Clinical and Environmental Teratology, Research Department, Alfred I. DuPont Hospital for Children, Wilmington, DE. Objectives After completing this article, readers should be able to: 1. List the environmental drugs, chemicals, and physical agents that have been documented to result in congenital malformations and have reproductive effects. 2. List the requirements for a teratogenic exposure. 3. Describe the importance of dose when evaluating the risk of exposures. 4. Describe the most important advances in embryology, teratology, reproductive biology, genetics, and epidemiology in the past 50 years. When I was a medical student at the University of Rochester, I was fortunate to have James G. Wilson, an embryologist, as one of my teachers in the anatomy course. He was working on the effects of radiation on the embryo, which is how I became interested in congenital malformations. Many of the faculty members discouraged me from pursuing the study of the causes of birth defects as an academic goal, “Because we are never going to solve that problem.” In 1955, when I had completed medical school and graduate school, the scientific world did not even have the correct figure for the number of human chromosomes. Gregg had recently described the teratogenicity of rubella virus infection during pregnancy. The teratogenic risk of the folic acid antagonists was established, and there were experimental studies indicating that nutritional deficiencies could produce birth defects in animals. What have we learned and accomplished in the past 50 years? Thousands of previously unknown genetic diseases have been described, and many of their genes have been identified. The fields of prenatal intrauterine diagnoses, intervention, and treatment have been created. Metabolic and biochemical screening have become standard care for pregnant women and newborns. More than 50 teratogenic environmental drugs, chemicals, and physical agents have been described by using modern epidemiologic tools and the superb talents of clinical dysmorphologists. The basic science and clinical rules for evaluating teratogenic risks have …

Congenital malformations among infants whose mothers had gestational diabetes or preexisting diabetes.

Diabetes type 1 is associated with an increased risk for infant congenital malformations. It is debated whether this is true also at gestational diabetes. To study occurrence of congenital malformations in infants whose mothers had preexisting or gestational diabetes. A register study covering over 1.2 million Swedish births in 1987-1997 based on the Swedish health registries. We identified from the Medical Birth Registry 3864 infants born of women with preexisting diabetes and 8688 infants born of women with gestational diabetes. Congenital malformations identified in the Medical Birth Registry, the Registry of Congenital Malformations, and the Hospital Discharge Registry. The rates of congenital malformations among these infants was compared with the population rates. At preexisting diabetes, the total malformation rate was 9.5% while the rate at gestational diabetes was similar to the population rate, 5.7%. At preexisting diabetes, certain conditions were more common than expected: orofacial clefts, cardiovascular defects, oesophageal/intestinal atresia, hypospadias, limb reduction defects, spine malformations, and polydactyly. For some of these conditions, an excess was found also for infants whose mothers had gestational diabetes. Infants with multiple malformations were in excess at preexisting diabetes but not at gestational diabetes but the specific type of malformations involved were similar in the two diabetes groups. It is suggested that in the group of gestational diabetes exists a subgroup with an increased risk for a diabetes embryopathy, perhaps due to preexisting but undetected diabetes type 2.

VATER non-random association of congenital malformations: study based on data from four malformation registers.

This study was undertaken to find a strict, unbiased epidemiological delineation of the VATER non-random association of congenital malformations and, based on registry information, to identify a group of probable VATER association infants suitable for etiological analyses. Information on 5,260 infants with multiple malformations was collected from four large registers of congenital malformations. Data were analyzed using a statistical method in which various putative confounders were controlled for. Our results indicate the existence of a distinct group of malformations corresponding to the VATER association: esophageal atresia, anal atresia, upper preaxial limb reduction defects, and costo-vertebral malformations. A subdivision into an upper and a lower group of VATER association was indicated, with heart malformations associated with the upper group and kidney malformations associated with the lower group. Restricting the inclusion criteria for VATER association to the above mentioned core malformations, few infants seem to belong to the VATER association, thus limiting the possibilities of carrying out etiological analyses. A relatively large number of infants may belong to a family of related conditions among which VATER association is a subgroup. In the search for risk factors, a strict definition of the VATER association is needed in order to not dilute the study material with irrelevant cases. The present study provides such strict inclusion criteria.

Teratogenic effects of antiepileptic drugs: use of an International Database on Malformations and Drug Exposure (MADRE).

The study goal was to assess teratogenic effects of antiepileptic drugs (AEDs) through the use of a surveillance system (MADRE) of infants with malformations. Information on all malformed infants (1990-1996) with maternal first-trimester drug exposure was collected by the International Clearinghouse for Birth Defects and Monitoring Systems (ICBDMS). Cases were defined as infants presenting with a specific malformation, and controls were defined as infants presenting with any other birth defect. Exposure was defined by the use of AEDs during the first trimester of pregnancy. The association of AEDs with malformations was then estimated by calculating the odds ratios with 95% confidence intervals and testing their homogeneity among registries. Among 8005 cases of malformations, 299 infants were exposed in utero to AEDs. Of those exposed to monotherapy, 65 were exposed to phenobarbital, 10 to methylphenobarbital, 80 to valproic acid, 46 to carbamazepine, 24 to phenytoin, and 16 to other AEDs. Associations were found for spina bifida with valproic acid. Infants exposed to phenobarbital and to methylphenobarbital showed an increased risk of oral clefts. Cardiac malformations were found to be associated with phenobarbital, methylphenobarbital, valproic acid, and carbamazepine. Hypospadias was associated with valproic acid. Porencephaly and other specified anomalies of brain, anomalies of face, coarctation of aorta, and limb reduction defects were found to be associated with valproic acid. Using the MADRE system, we confirmed known teratogenic effects of AEDs. We also found increased risks for malformations that had never been reported associated with AEDs or for which the association was suggested by case reports.

Congenital malformations in the southeast of Sweden—a registry study with validation

A study was made of the occurrence of congenital malformations in the southeast region of Sweden, utilizing all available relevant health registries. Östergötland county had been pinpointed in a routine surveillance as having an increased malformation risk. Various validations of the register data were undertaken and different types of errors were detected. An increased risk was seen, in Östergötland county compared to the reference counties, for specific types of malformations: preauricular appendices, pylorostenosis, uterine/vaginal malformations, foot deformities, limb reduction defects and cardiovascular malformations. Variable classification or registration artefacts explained the excess among the first four conditions. Limb reduction defects were also mis‐coded, but the increased risk in Östergötland county may persist. Conclusion: There is an increased risk of major cardiovascular malformations in Östergötland county compared to the reference counties that also shows an uneven distribution within the county.

Congenital malformations in the southeast of Sweden--a registry study with validation.

A study was made of the occurrence of congenital malformations in the southeast region of Sweden, utilizing all available relevant health registries. Ostergötland county had been pinpointed in a routine surveillance as having an increased malformation risk. Various validations of the register data were undertaken and different types of errors were detected. An increased risk was seen, in Ostergötland county compared to the reference counties, for specific types of malformations: preauricular appendices, pylorostenosis, uterine/vaginal malformations, foot deformities, limb reduction defects and cardiovascular malformations. Variable classification or registration artefacts explained the excess among the first four conditions. Limb reduction defects were also mis-coded, but the increased risk in Ostergötland county may persist. There is an increased risk of major cardiovascular malformations in Ostergötland county compared to the reference counties that also shows an uneven distribution within the county.

Differential alteration by thalidomide of the glutathione content of rat vs. rabbit conceptuses in vitro

Thalidomide has been shown to cause limb reduction defects in rabbits with much greater potency than in rats, possibly due to inherent biochemical differences between the two species. Whole embryo culture was used to make direct comparisons between thalidomide-sensitive New Zealand White rabbits and thalidomide-resistant Sprague-Dawley rats, focusing on the possible roles of glutathione (GSH) and cysteine in mechanisms of thalidomide teratogenicity. Conceptuses were treated by adding thalidomide (0, 5, 15, and 30 μM) directly to the culture media containing conceptuses of similar gestational stages. Embryos and visceral yolk sacs (VYS) were measured for changes in GSH and cysteine content using HPLC after 24 h of exposure in vitro. Thalidomide-induced (15 and 30 μM) depletion of VYS GSH occurred only in the rabbit, where GSH concentrations (pmol/μg protein) fell significantly to about 50% of control. Rat VYS did not show a significant GSH depletion at any thalidomide concentration tested. Comparison between species showed that the control rabbit VYS contained 35% less GSH than the control rat VYS. Control rat embryos and control rabbit embryos contained similar concentrations of GSH, but thalidomide treatment preferentially depleted GSH in the rabbit at lower thalidomide concentrations (5 μM). Cysteine concentrations were not significantly altered from control in the embryo or VYS of either species when treated with thalidomide. However, although control cysteine concentrations did not differ significantly between rat and rabbit VYS, control cysteine levels in rabbit embryos were 65% lower than those in control rat embryos. Rabbit conceptuses displayed lower species-specific GSH and cysteine levels and a greater propensity for thalidomide-induced GSH depletion than in rat conceptuses, consistent with the greater sensitivity of the rabbit to thalidomide teratogenicity. These thalidomide-induced and inherent species differences implicate a possible role for GSH and redox status in the mechanisms of thalidomide teratogenicity.

Sonographic diagnosis of limb reduction defects in a fetus with haemoglobin Bart's disease at 12 weeks of gestation

Limb reduction defect is a rare event but is found in eight per cent of fetuses affected by haemoglobin Bart's disease. We present a case of haemoglobin Bart's disease with terminal transverse limb reduction defects of all four limbs diagnosed by abdominal ultrasound examination at 12 weeks of gestation. The pregnancy was terminated by suction curettage. Just prior to the procedure, transabdominal needle embryoscopy was performed and this confirmed the sonographic diagnosis. The present case demonstrates the need and feasibility of a detailed anatomic survey of a fetus affected by haemoglobin Bart's disease at 12 weeks. This is particularly relevant if the patient is considering the option of intra-uterine therapy. Copyright © 1999 John Wiley & Sons, Ltd.

Sonographic diagnosis of limb reduction defects in a fetus with haemoglobin Bart's disease at 12 weeks of gestation

Limb reduction defect is a rare event but is found in eight per cent of fetuses affected by haemoglobin Bart's disease. We present a case of haemoglobin Bart's disease with terminal transverse limb reduction defects of all four limbs diagnosed by abdominal ultrasound examination at 12 weeks of gestation. The pregnancy was terminated by suction curettage. Just prior to the procedure, transabdominal needle embryoscopy was performed and this confirmed the sonographic diagnosis. The present case demonstrates the need and feasibility of a detailed anatomic survey of a fetus affected by haemoglobin Bart's disease at 12 weeks. This is particularly relevant if the patient is considering the option of intra-uterine therapy.

Multivitamin supplementation and risk of birth defects.

It is widely accepted that supplementation with folic acid, a B vitamin, reduces the risk of neural tube defects (NTDs). This case-control study tested the hypothesis that multivitamins reduce risks of selected birth defects other than NTDs. Infants with and without birth defects and aborted fetuses with birth defects were ascertained in the greater metropolitan areas of Boston, Philadelphia, and Toronto during 1993-1996. Mothers were interviewed within 6 months after delivery about a variety of factors, including details on vitamin use. Eight case groups were included: cleft lip with or without cleft palate, cleft palate only, conotruncal defects, ventricular septal defects, urinary tract defects, limb reduction defects, congenital hydrocephaly, and pyloric stenosis (n's ranged from 31 to 186). Controls were 521 infants without birth defects (nonmalformed controls) and 442 infants with defects other than those of the cases (malformed controls). Daily multivitamin supplementation was evaluated according to gestational timing categories, including periconceptional use (28 days before through 28 days after the last menstrual period). Odds ratios (ORs) below 1.0 were observed for all case groups except cardiac defects, regardless of control type. For periconceptional use, ORs with 95% confidence intervals that excluded 1.0 were estimated for limb reduction defects using both nonmalformed controls (OR = 0.3) and malformed controls (OR = 0.2) and for urinary tract defects using both nonmalformed controls (OR = 0.6) and malformed controls (OR = 0.5). Statistically significant ORs for use that began after the periconceptional period were observed for cleft palate only and urinary tract defects. These data support the hypothesis that periconceptional vitamin supplementation may extend benefits beyond a reduction in NTD risk. However, other than folic acid's protecting against NTDs, it is not clear what nutrient or combination of nutrients might affect risk of other specific defects.

Maternal corticosteroid use and risk of selected congenital anomalies.

Evidence for the teratogenicity of corticosteroids in humans is limited and has resulted in inconsistent recommendations regarding their use during early pregnancy. We examined the association between women's corticosteroid use during the periconceptional period (1 month before to 3 months after conception) and delivering infants with selected congenital anomalies. Data were derived from a population-based case-control study that included cases of orafacial clefts (n = 662), conotruncal heart defects (n = 207), neural tube defects (n = 265), and limb reduction defects (n = 165). Information on medication use was collected via maternal telephone interviews. Corticosteroid use was associated with an increased risk for isolated cleft lip with or without cleft palate (odds ratio 4.3, 95% confidence interval 1.1-17.2) and isolated cleft palate (odds ratio 5.3, 95% confidence interval 1.1-26.5). Increased risks were not observed for the other anomaly groups studied. These data in conjunction with other epidemiologic data suggest a possible causal association between cleft lip and palate and corticosteroid use.