Epidemiological characteristics of amniotic band sequence (ABS) and body wall complex (BWC): are they two different entities?

Amniotic band syndrome and limb body wall complex in Europe 1980-2019

Amniotic band syndrome (ABS) and limb body wall complex (LBWC) have an overlapping phenotype of multiple congenital anomalies and their etiology is unknown. We aimed to determine the prevalence of ABS and LBWC in Europe from 1980 to 2019 and to describe the spectrum of congenital anomalies. In addition, we investigated maternal age and multiple birth as possible risk factors for the occurrence of ABS and LBWC. We used data from the European surveillance of congenital anomalies (EUROCAT) network including data from 30 registries over 1980-2019. We included all pregnancy outcomes, including live births, stillbirths, and terminations of pregnancy for fetal anomalies. ABS and LBWC cases were extracted from the central EUROCAT database using coding information responses from the registries. In total, 866 ABS cases and 451 LBWC cases were included in this study. The mean prevalence was 0.53/10,000 births for ABS and 0.34/10,000 births for LBWC during the 40 years. Prevalence of both ABS and LBWC was lower in the 1980s and higher in the United Kingdom. Limb anomalies and neural tube defects were commonly seen in ABS, whereas in LBWC abdominal and thoracic wall defects and limb anomalies were most prevalent. Twinning was confirmed as a risk factor for both ABS and LBWC. This study includes the largest cohort of ABS and LBWC cases ever reported over a large time period using standardized EUROCAT data. Prevalence, clinical characteristics, and the phenotypic spectrum are described, and twinning is confirmed as a risk factor.

Disseminated intravascular coagulation complicated by amniotic band syndrome associated with deceased fetal umbilical cord following fetoscopic laser surgery

Fetoscopic laser surgery occasionally causes amniotic band syndrome, in which the disrupted amniotic membrane constricts fetal body parts, leading to functional or morphological loss. We report a case of fetal distress at 31 weeks of gestation in the larger surviving twin after fetoscopic laser surgery for selective intrauterine growth restriction, necessitating emergent cesarean section. Physical examination of the infant showed constriction rings caused by a disrupted amniotic membrane on the digits, and the distal part of the right index finger was necrotic because of tight strangulation by an amniotic band with the umbilical cord of the deceased smaller twin. Laboratory data showed severe coagulopathy, and the infant was diagnosed with disseminated intravascular coagulation (DIC). Immediate treatment improved his condition. DIC may have been associated with the necrotic finger, which was strangulated by the umbilical cord of the deceased fetus, because neither maternal coagulopathy nor an underlying neonatal disorder was detected.

Prevalence, risk factors, and outcome of postprocedural amniotic band disruption sequence after fetoscopic laser surgery in twin-twin transfusion syndrome: a large single-center case series

BACKGROUND

Postprocedural amniotic band disruption sequence is a condition that is associated with intrauterine interventions, and it is characterized by a constriction of the limbs or umbilical cord by fibrous strands, leading to edema, amputation, and/or fetal demise.

OBJECTIVE

To evaluate the prevalence of, risk factors for, and the outcome of postprocedural amniotic band disruption sequence after fetoscopic laser surgery in twin-twin transfusion syndrome cases.

STUDY DESIGN

All consecutive cases of twin-twin transfusion syndrome treated with fetoscopic laser coagulation of the vascular anastomoses at our center between January 2002 and March 2019 were included in the study. The occurrence of postprocedural amniotic band disruption sequence in these cases was recorded, and the potential risk factors were analyzed.

RESULTS

Postprocedural amniotic band disruption sequence was detected, at birth, in 2.2% (15/672) of twin-twin transfusion syndrome cases treated with fetoscopic laser surgery, in both the recipients (10/15, 67%) and the donors (5/15, 33%). Postprocedural amniotic band disruption sequence primarily affected the lower extremities (11/15, 73%) and, less frequently, the upper extremities (2/15, 13%), both the upper and lower extremities (1/15, 7%), or the umbilical cord (1/15, 7%). Postprocedural amniotic band disruption sequence led to the amputation of toes in 5 of 15 cases (33%) and resulted in fetal demise because of constriction of the umbilical cord in 1 case (7%). The independent risk factors identified for postprocedural amniotic band disruption sequence were lower gestational age at laser surgery (odds ratio per week, 1.43; 95% confidence interval, 1.12-1.79; P=.003) and the presence of postprocedural chorioamniotic membrane separation on antenatal ultrasound examination (odds ratio, 41.66; 95% confidence interval, 5.44-319.25; P<.001).

CONCLUSION

The prevalence of postprocedural amniotic band disruption sequence is low, but, when present, it may lead to severe consequences, with amputation of extremities or fetal demise occurring in more than one-third of the cases. Lower gestational age at the time of laser therapy and chorioamniotic membrane separation are independent risk factors for the postprocedural amniotic band disruption sequence.

Body stalk anomalies in pig-Definition and classification

The presence of body wall closing defects (abdominoschisis and thoracoabdominoschisis) in combination with other congenital malformations was studied in the pig (Sus scrofa domesticus). After clinical examination and literature review, body wall defects with multiple congenital anomalies in eight pigs were described, and classified using anatomical and embryological criteria. Several BSA presentations were identified and classified as follows: (a) BSA Type I: fetus with spinal and UC defects, thoracoabdominoschisis, anal atresia and/or other internal organs structural defects, and structural limb defects; (b) BSA Type II: fetus with spinal and UC defects, thoracoabdominoschisis, anal atresia and/or other internal organs structural defects, and nonstructural limb defects; (c) BSA Type III: fetus with spinal and UC defects, abdominoschisis, anal atresia and/or other internal organs structural defects, and structural limb defects; and (d) BSA Type IV: fetus with spinal and UC defects, abdominoschisis, anal atresia and/or other internal organs structural defects, and nonstructural limb defects. Two types of LBWC were differentiated: LBWC Type I: characterized by thoracoabdominoschisis and structural limb defects, and LBWC Type II: characterized by abdominoschisis and structural limb defects, corresponding to BSA type I and type III. This is the first report on BSA and LBWC in the pig.

Body wall defects and amniotic band syndrome in pig (Sus scrofa domesticus)

The amniotic band syndrome is a congenital condition. It is characterized by the presence of fibrous amniotic bands that may entangle or entrap different foetal parts in utero, resulting in deformation, malformation or disruption. We report on a female piglet presenting amniotic band adherences in the right abdominal flank, several body wall defects (gastroschisis, abdominoschisis with omphalocele), severe scoliosis, anomalous umbilical cord with single umbilical artery, anal atresia, anomalous liver and absent gall bladder, hypoplastic genitalia, ankylosis and arthrogryposis in pelvic limbs, and bilateral patellar agenesia. The ethiopatogenia is discussed, as well as the comparative and embryological implications.

Limb body wall complex: Its delineation and relationship with amniotic bands using clustering methods

BACKGROUND

Despite the numerous reports on the limb body wall complex (LBWC), this association has never been adequately defined. Amniotic bands (AB) are frequently present but their role remains unclear. Since most reports were based on clinical and often subjective diagnoses, the aim of this work was to define LBWC and the role of AB, minimizing subjectivity.

METHODS

Data were obtained from the ECLAMC maternity hospitals network database. A total of 450 live and stillborn infants, born during 1967-2013, with AB or the LBWC were selected. A hierarchical cluster analysis was used to classify cases into homogeneous groups (sharing similar associated defects); robustness of the classification was confirmed with a discriminant analysis. The frequency of associated defects was compared among groups; those whose frequency differed significantly were included in a logistic regression to establish their association within each group.

RESULTS

The cluster analysis identified two groups: a body wall defect (BWD) predominating in one, AB in the other. These groups were further divided into: BWD (cases with only BWD), AB (with only AB), BWD + AB, and NONE (with neither). Association with caudal defects and lower limb amelia was observed for BWD, with cephalic defects and upper limb amputations for BWD + AB.

CONCLUSIONS

The results, obtained with the least possible subjectivity, indicated that BWD and BWD + AB are different conditions. Since BWD specifically associates with amelia, we propose that this defect and not any limb deficiency should be considered as inclusion criterium and that it should be included in the BWD acronym as LBWC.

Amniotic constriction band: a report of two cases with unique clinical presentations

Amniotic constriction band is a rare clinical entity with varied manifestations that range from a combination of congenital malformations to isolated malformations that are unique to each patient. The etiology of this entity remains unknown. Herein, we highlight two cases of amniotic constriction band that presented to our unit with unique clinical characteristics. To the best of our knowledge, an isolated circumferential band of scarring on the face with ocular involvement, as demonstrated by the first case, and a combination of bilateral complete cleft lip and palate with bilateral microphthalmia, auto-amputation of the right thumb, and a constriction band on the left thumb, as demonstrated by the second case, are extremely rare presentations of amniotic constriction band that were not previously reported in the literature and therefore necessitate a special mention. We discuss potential etiologies for these cases and review the existing literature on this entity.

The prevalence of amnion rupture sequence, limb body wall defects and body wall defects in Alberta 1980-2012 with a review of risk factors and familial cases

Prevalence rates of amnion rupture sequence, limb body wall defect, and body wall defects vary widely. Comparisons are difficult due to small case numbers and the lack of agreement of definition, classification, and pathogenesis. This study reports the prevalence of cases classified in five distinct categories. The Alberta Congenital Anomalies Surveillance System data on live births, stillbirths, and terminations of pregnancy (<20 weeks gestation) occurring between 1980 through 2012 with the ICD-10 Royal College of Paediatrics and Child Health Adaptation codes used for congenital constriction bands (Q79.80) and body wall complex (Q89.7) were reviewed. During the 33-year-study period, there were 153 eligible cases ascertained from 1,411,652 live births and stillbirths, giving a prevalence of 1.08/10,000 total births. There were more males (52%) than females (45%) and 3% were of unknown sex. The average maternal age, birth weight, and gestation was 27 years, 2,701 g, and 35 weeks, respectively. Limb deficiencies occurred in 78% of cases. Amniotic bands with limb deficiency was the most common phenotype (48%). Digital limb deficiency was the most frequent type (56%); however, cases with body wall defects had more severe types of limb deficiencies. The upper limbs only were affected more times (44%), and there was no side preference. Most cases are sporadic but a number of familial occurrences have been reported although some have insufficient documentation and others misdiagnosed. A review of putative risk factors gives conflicting results. © 2016 Wiley Periodicals, Inc.

Limb body wall complex, amniotic band sequence, or new syndrome caused by mutation in IQ Motif containing K (IQCK)?

Limb body wall complex (LBWC) and amniotic band sequence (ABS) are multiple congenital anomaly conditions with craniofacial, limb, and ventral wall defects. LBWC and ABS are considered separate entities by some, and a continuum of severity of the same condition by others. The etiology of LBWC/ABS remains unknown and multiple hypotheses have been proposed. One individual with features of LBWC and his unaffected parents were whole exome sequenced and Sanger sequenced as confirmation of the mutation. Functional studies were conducted using morpholino knockdown studies followed by human mRNA rescue experiments. Using whole exome sequencing, a de novo heterozygous mutation was found in the gene IQCK: c.667C>G; p.Q223E and confirmed by Sanger sequencing in an individual with LBWC. Morpholino knockdown of iqck mRNA in the zebrafish showed ventral defects including failure of ventral fin to develop and cardiac edema. Human wild-type IQCK mRNA rescued the zebrafish phenotype, whereas human p.Q223E IQCK mRNA did not, but worsened the phenotype of the morpholino knockdown zebrafish. This study supports a genetic etiology for LBWC/ABS, or potentially a new syndrome.

ADAM "sequence" part II: hypothesis and speculation

Noted for centuries in humans, a relatively hairless mammal [e.g., Hallero, 1766; Hohl, 1828 in Klunker, 2003], the so-called amniotic deformities, adhesions, mutilations (ADAM) sequence remains causally and pathogenetically incognito. In 1930 Streeter stated " apodictically" that no evidence has been found that intra-uterine amputation is due to amniotic bands or adhesions …" and that his 16 cases provided (histological) evidence for a "germinal origin." He concluded that an amniotic cord was "not an adhesion or inflammatory product but … an anomalous developmental structure and present from the outset." In survivors the "traces" of damaged limb-buds "reveal the scars of poor germ-plasm." In 1958, Willis, in dismissing the amniotic origin of the ADAM defects (or "Streeter" or "Simonart" bands) quoted Keith [1940] to the effect that "(a)mniotic adhesions … are always produced by … the fetus – as a result of dysplasia in foetal tissues. They are the result, not the cause, of foetal malformations." Streeter [1930] mentions a potential familial case (56-year-old man and his mother), not controlled by photographs or other records and concluded "that the (ADAM) deformity is not easily transmissible," but "due to the constitution of the germ-plasm." Torpin [1968] concluded, as apodictically as Streeter and Willis, that "… proof of amnion rupture without damage to the chorionic sac is no longer "in question." Considering Torpin's decades-long study of the ADAM phenomenon and review of 494 references (missing many) it is surprising that he does not discuss the relationship between the apparent ADAM defects and other, internal anomalies that maybe present in an affected fetus or infant not evidently caused by the amniotic disruptions, adhesions or mutilations, unless his mind was made up. Our review of these internal and other presumed primary malformations in ADAM is ongoing. However, on a preliminary basis, it seems likely to us that: (1) there is an increased prevalence of such primary anomalies in the ADAM condition confirming the view and experience of others, for example Czeizel et al. [1993]; (2) these malformations (e.g., heterotaxy) may arise as early as gastrulation; (3) that, given the ADAM phenomenon is exclusively ascertained as the ADAM phenotype in fetuses and infants, that is, that its cause and ascertainment are completely congruent, then the apparent amniotic defect must also be regarded as a malformation; (4) that in such a case the ADAM phenomenon with associated primary malformation(s) is a form of syndromal pleiotropy due to one cause yet to be elucidated. To that end we recommend archiving DNA from all affected fetuses coming to autopsy and their parents and placentas and surgical tissues of all viable affected infants for ultimate exome or genome sequencing perhaps with special attention to the syncytin genes.

[Complex of amniotic deformities, adhesions, mutilations: Endless debate]

Amniotic deformities, adhesions, mutilations (ADAM) complex is a broad heterogeneous spectrum of congenital anomalies. ADAM complex is characterized by constriction rings, amputation of fingers or limbs and the presence of the amniotic band. However, it may also involve craniofacial disruptions, body wall defects and internal organ abnormalities. The aim of this review is to present the results found in regard to ADAM complex from its historical background, clinical manifestations, epidemiology, etc. In particular, our attention was focused on demonstrating the varying etiopathogenesis theories of ADAM complex and their contradictions. The study was conducted using the databases of PubMed, EBSCO host, Ovid, SpringerLink, Scopus, nature.com, JAMA and ScienceDirect with the following keywords for the search: "amniotic band syndrome", "amniotic band sequence", "Streeter dysplasia", "ADAM complex". In this study we used 22 full-text articles. Patients with ADAM complex require a complete pre- and postnatal evaluation to integrate the diagnosis and to decide on timely treatment. It is important for clinicians and surgeons to possess knowledge of this entity. Further research is necessary to establish a nosological basis.

Comparative study of clinical characteristics of amniotic rupture sequence with and without body wall defect: further evidence for separation

BACKGROUND

Amniotic rupture sequence (ARS) is a disruption sequence presenting with fibrous bands, possibly emerging as a result of amniotic tear in the first trimester of gestation. Our comparative study aims to assess whether there is a difference in the clinical pattern of congenital limb and internal organ anomalies between ARS with body wall defect (ARS-BWD) and ARS without BWD (ARS-L).

METHODS

Among 1,706,639 births recorded between 1998 and 2006, 50 infants with a diagnosis of ARS were reported to the Polish Registry of Congenital Malformations. The information on 3 infants was incomplete, thus only 47 cases were analyzed. These infants were classified into groups of ARS-L (38 infants) and ARS-BWD (9 infants).

RESULTS

The ARS-BWD cases were more frequently affected by various congenital defects (overall p < 0.0001), and in particular by urogenital malformations (p = 0.003). In both groups, limb reduction defects occurred in approximately 80% of cases; however, minor and distal limb defects (phalangeal or digital amputation, pseudosyndactyly, constriction rings) predominated in the ARS-L group (p = 0.0008). The ARS-L group also had a higher frequency of hand and upper limb involvement.

CONCLUSIONS

This observation suggests that amniotic band adhesion in ARS-L takes place at a later development stage. Although limited by a small sample size, our study contributes to the growing evidence that both ARS entities represent two nosologically distinct conditions.

Pseudoamniotic band syndrome: a rare complication of monochorionic twins with fetofetal transfusion syndrome treated by laser coagulation

OBJECTIVE

The purpose of this study was to assess the incidence and risk factors of limb constriction defects that are related to pseudoamniotic band syndrome (PABS) after selective fetoscopic laser surgery (FLS) in fetofetal transfusion syndrome (FFTS).

STUDY DESIGN

All consecutive cases of FFTS that were treated by selective FLS between 1999 and 2006 were examined prospectively for PABS at the time of delivery. Incidence and characteristics of PABS were reported. Univariate analysis was conducted to look for potential risk factors of developing PABS.

RESULTS

The 438 consecutive FFTS cases were treated at 15-26 weeks of gestation; PABS developed in 8 cases (1.8 %). The affected twin was always the former recipient. The diagnosis was made prenatally in 2 of 8 cases (25%). All cases survived the perinatal period. PABS affected fetal leg, arm, and foot in 3, 4, and 1 cases, respectively. In 5 (62.5%) and 7 (87.5%) cases, PABS occurred after premature rupture of membranes and intrauterine death of the donor, respectively. In 4 cases (50%), there was both premature rupture of membranes (PROM) and intrauterine fetal death; in 3 cases (37.5%), there was intrauterine fetal death alone, and in 1 case (12.5%), there was PROM alone. In the remaining 430 cases, PROM occurred in 62 cases (14.4%) and 66 cases (15.3%) within and after 3 weeks after surgery, respectively. PROM was significantly more frequent within the group that was complicated with PABS than within the rest of the cohort (P = .05). No maternal, fetal, or perioperative risk factor could be identified.

CONCLUSION

Awareness and targeted serial ultrasound evaluation in this high-risk group may improve prenatal diagnosis, counseling, and management of PABS after FLS.

Patterns of severe abdominal wall defects: Insights into pathogenesis, delineation, and nomenclature

BACKGROUND

During the last decade, descriptions of malformation complexes involving an abdominal wall defect (AWD) have repeatedly appeared in the literature, and there has been frequent confusion regarding nomenclature, definitions, and delineations. The aims of this work were to evaluate possible embryological relationships among AWD cases, review the related nomenclature, identify patterns involving AWDs, and stress the importance of complete clinical descriptions. METHODS Cases diagnosed as AWD complexes were selected from live--and stillborn infants of the Hospital Materno Infantil Ramón Sardá, Buenos Aires, and from the Laboratory of Perinatal Pathology, Buenos Aires, Argentina. They were sorted by the location of the AWD, the umbilical cord length, and the presence or absence of a persistent cloaca. The findings in 26 cases were described, according to proposed definitions.

RESULTS

Three patterns could be identified: 1) the AWD involving the umbilical ring, a persistent or exstrophic cloaca, and a spinal cord anomaly; 2) the AWD extending laterally to the umbilical ring, severe unilateral limb defects, and same-sided agenesis of abdominal organs; and 3) the AWD not involving the umbilical ring, clefts, exencephaly, and amputations. Furthermore, overlapping among these patterns was observed, and possible involved mechanisms are discussed.

CONCLUSIONS

The observed overlapping among patterns suggested that malformation complexes involving AWDs might not be independent conditions but rather belong to a common and broader spectrum of anomalies. Complete clinical descriptions, the avoidance of synonyms and generalizations, and strictly defined inclusion criteria are proposed for a better understanding of pathogenetic pathways in, and relationships among, AWD complexes.

Gastroschisis and associated defects: An international study

Our objective was to evaluate the frequency and type of malformations associated with gastroschisis in a large pool of international data, to identify malformation patterns, and to evaluate the role of maternal age in non-isolated cases. Case-by-case information from 24 registries, all members of the International Clearinghouse for Birth Defects Surveillance and Research (ICBDSR), were evaluated. After the exclusion of other abdominal wall defects cases were classified as: (a) isolated; (b) recognizable syndrome, chromosomal or not; (c) multiple congenital anomalies (MCA). Our results showed that out of 3,322 total cases 469 non-isolated cases were registered (14.1%): 41 chromosomal syndromes, 24 other syndromes, and 404 MCA. Among MCA four groups of anomalies were most frequent: CNS (4.5%), cardio-vascular (2.5%), limb (2.2%), and kidney anomalies (1.9%). No similar patterns emerged except two patterns resembling limb-body wall complex and OEIS. In both of them the gastroschisis could be however misclassified. Chromosomal trisomies and possibly non-syndromic MCA are associated with an older maternal age more than isolated cases. On consideration of our data and the most valid studies published in the literature, the best estimate of the proportion of gastroschisis associated with major unrelated defects is about 10%, with a few cases associated to recognizable syndromes. Recognized syndromes with gastroschisis seem to be so exceptional that the well documented and validated cases are worth being published as interesting case report. An appropriate case definition in etiological studies should include only isolated gastroschisis after an appropriate definition of isolated and non-isolated cases and a thorough case-by-case review.

Finally, a sense of closure? Animal models of human ventral body wall defects

Malformations concerning the ventral body wall constitute one of the leading categories of human birth defects and are present in about one out of every 2000 live births. Although the occurrence of these defects is relatively common, few detailed experimental studies exist on the development and closure of the ventral body wall in mouse and human. This field is further complicated by the array of theories on the pathogenesis of body wall defects and the likelihood that there is no single cause for these abnormalities. In this review, we summarize what is known concerning the mechanisms of normal ventral body wall closure in humans and mice. We then outline the theories that have been proposed concerning human body wall closure abnormalities and examine the growing number of mouse mutations that impact normal ventral body wall closure. Finally, we speculate how studies in animal models such as mouse and Drosophila are beginning to provide a much-needed mechanistic framework with which to identify and characterize the genes and tissues required for this vital aspect of human embryogenesis.

Unusual congenital abdominal wall defect and review

Abdominal wall defects distant from the umbilicus are very unusual. We describe a patient with a congenital defect adjacent and external to the lateral border of the recti muscles, rounded in shape, bilateral and symmetrical, but affecting different structures in each side, musculocutaneous agenesis in the left side and only muscle agenesis in the right one. The morphologic characteristics of the defect and the absence of associated anomalies, suggest that this anomaly may be the result of an event acting during phenogenesis. We consider that this defect is different from other structural abnormalities of the anterior abdominal wall which occur much earlier at certain periods of the embryogenesis. Though the etiology is speculative, we could postulate a disruptive origin of the defect of unknown cause.

Clinical and epidemiological studies of amniotic deformity, adhesion, and mutilation (ADAM) sequence in a South American (ECLAMC) population

Amniotic deformity, adhesion, and mutilation (ADAM) sequence is a heterogeneous condition, with a broad spectrum of anomalies, where intrinsic causes, as defect of germ plasm, vascular disruption, and disturbance of threshold boundaries of morphogens during early gastrulation, alternate with extrinsic causes as amniotic band rupture to explain the condition. This study aimed to identify which phenotypes could be considered as ADAM sequence, determine the prevalence rate, and disclose risk factors for this sequence. We identified 270 cases defined as having some skin evidence of constriction band, plus those having limb defects suggestive of ADAM sequence, among 3,020,896 live and stillborns in the years 1982 to 1998 in ECLAMC (Latin American Collaborative Study of Congenital Malformations). Half of the cases presented mutilation (reduction), and deformity (ring constriction) affecting distal parts of fingers or toes bilaterally, without associated defects. Acrania, cephalocele, typical or atypical facial clefts, eyelid coloboma, and celosomia were also observed being significantly associated with the skin lesion. One affected infant in every 11,200 births, was found with stable trends during the last 17 years. There was an excess of cases in populations living at high altitude, stillborns, and neonatal infant dead. Among ADAM cases there was an excess of mothers with a prenatal history of febrile acute illness, medication drug use, or vaginal bleeding during the first trimester of pregnancy. Higher than expected frequencies of first-born child, premature birth, low birth weight for gestational length, and non-cephalic fetal presentation were also found. The observed geographic difference in birth prevalence could be a useful indication to study specific genetic and environmental candidate factors to ADAM susceptibility.

Epidemiologic analysis of maternal factors and amniotic band defects

BACKGROUND

The group of defects identified as amniotic bands includes amnion rupture sequence (ARS) and body wall complex (BWC). Little is known about risk factors for either ARS or BWC, except that maternal age has been shown to affect risk inversely.

METHODS

The present analysis used data collected from 1976 to 1998 as part of an ongoing case control study of birth defects in the metropolitan areas of Boston, Philadelphia, and Toronto. There were 73 cases with ARS and 11 cases with BWC. ARS cases were further subdivided according to affected structures: there were 53 with only limbs affected (ARS-L) and 20 with nonlimb defects with or without limb defects (ARS-NL). The control group comprised 12,227 subjects with other major malformations. Mothers were interviewed within 6 months of delivery about demographic, reproductive, medical, and behavioral factors.

RESULTS

Multivariate adjusted odds ratios for BWC were increased more than threefold for maternal age < 25 years and maternal education < 12 years, but neither estimate was statistically significant. Corresponding estimates for ARS-L and ARS-NL ranged from 13 to 1.5 and also were not statistically significant. Cases were less likely to be white non-Hispanic than controls and the odds ratio for ARS-NL excluded the null. The multivariate adjusted odds ratio (MVOR) for unplanned pregnancy and BWC was 1.9 (95% confidence interval, 0.5-6.7) compared to 1.2 and 1.0 for ARS-L and ARS-NL, respectively. Neither parity nor maternal smoking was associated with any case group. The MVORs for first trimester acetaminophen use in relation to ARS-L and ARS-NL risks were 2.1 (1.1-3.9) and 3.4 (1.1-10.3), respectively. Such use was less common among BWC cases (MVOR was 0.4; 0.1-1.4).

CONCLUSIONS

Risk estimates tended to be similar for ARS-L and ARS-NL cases but different for BWC cases, suggesting different etiologies. These data suggest that young maternal age, low maternal education, unplanned pregnancy, and non-white/non-Hispanic race/ethnicity might increase the risk of BWC in offspring. Inceased risks for acetaminophen use should be interpreted with caution because they may be confounded by indication for use.

Body stalk defects, body wall defects, amniotic bands with and without body wall defects, and gastroschisis: comparative epidemiology

The presence of body wall defects with "evisceration" of thoracic and/or abdominal organs associated with other congenital anomalies, with or without limb deficiencies, is considered to be the body wall complex (BWC). The BWC is different from gastroschisis, which is usually a small body wall defect lateral to the umbilical cord that is not covered by any membrane and, in most of the cases, is an isolated defect. For the present analysis we separated the BWC group into three subgroups. One group was that of body stalk anomalies characterized by severe defects of the abdominal wall with absence of, or very small, umbilical cord, or this is continuing with the placenta. The second group was made up of those infants with body wall defects without amniotic bands, and the third group was of those children with body wall defects produced by amniotic bands. We considered two additional groups in the analysis, one was of infants with gastroschisis and the other those infants with amniotic bands without body wall affectation. We also included the control group (nonmalformed infants) for comparisons. From the results of our epidemiological study, we can conclude that amniotic bands with body wall affectation and amniotic bands without body wall defects are two different entities. The results also suggest that the characteristics of infants with amniotic bands with body wall defects are more similar to the group of infants with body stalk anomalies. This may indicate that the former group is produced during the very early gestation.