Prenatal predictors of need for cerebrospinal fluid diversion in infants following prenatal repair of open spina bifida; systematic review and meta-analysis.

OBJECTIVE: This study aimed to investigate prenatal predictors of the need for cerebrospinal fluid diversion in infants following prenatal repair of open spina bifida. DATA SOURCES: A systematic search was performed to identify relevant studies published from inception until June 2022 in the English language using the databases PubMed, Scopus, and Web of Science. STUDY ELIGIBILITY CRITERIA: We included retrospective and prospective cohort studies and randomized controlled trials reporting on prenatal repair of open spina bifida. METHODS: The random-effects model was used to pool the mean differences or odds ratios and the corresponding 95% confidence intervals. Heterogeneity was assessed using the I2 value. RESULTS: A total of 9 studies including 948 pregnancies undergoing prenatal repair of open spina bifida were included in the final analysis. Prenatal factors that were significantly associated with the need for postnatal cerebrospinal fluid diversion were gestational age at surgery ≥25 weeks (odds ratio, 4.2; 95% confidence interval, 1.8-9.9; I2=54%; P=.001), myeloschisis (odds ratio, 2.2; 95% confidence interval, 1.1-4.1; I2=0.0%; P=.02), preoperative lateral ventricle width ≥15 mm (odds ratio, 4.5; 95% confidence interval, 2.9-6.9; I2=0.0%; P<.0001), predelivery lateral ventricle width (mm) (mean difference, 8.3; 95% confidence interval, 6.4-10.2; I2=0.0%; P<.0001), and preoperative lesion level at T12-L2 (odds ratio, 2.5; 95% confidence interval, 1.03-6.3; I2=68%; P=.04). Factors that significantly reduced the need for postnatal shunt placement were gestational age at surgery <25 weeks (odds ratio, 0.3; 95% confidence interval, 0.15-0.6; I2=67%; P=.001) and preoperative lateral ventricle width <15 mm (odds ratio, 0.3; 95% confidence interval, 0.2-0.4; I2=0.0%; P<.0001). CONCLUSION: This study demonstrated that among fetuses that underwent surgical repair of open spina bifida, having gestational age at surgery of ≥25 weeks, preoperative lateral ventricle width of ≥15 mm, myeloschisis lesion type, and preoperative lesion level above L3 was predictive of the need for cerebrospinal fluid diversion during the first year of life.

Longitudinal evolution of central nervous system anomalies in fetuses with open spina bifida fetoscopic repair and correlation with neurologic outcome.

BACKGROUND: Open spina bifida is associated with central nervous system anomalies such as abnormal corpus callosum and heterotopias. However, the impact of prenatal surgery over these structures remains unclear. OBJECTIVE: This study aimed to describe longitudinal changes of central nervous system anomalies before and after prenatal open spina bifida repair and to evaluate their relationship with postnatal neurologic outcomes. STUDY DESIGN: Retrospective cohort study of fetuses with open spina bifida who underwent percutaneous fetoscopic repair from January 2009 to August 2020. All women had presurgical and postsurgical fetal magnetic resonance imaging, at an average of 1 week before and 4 weeks after surgery, respectively. We evaluated defect characteristics in the presurgical magnetic resonance images; and fetal head biometry, clivus supraocciput angle, and the presence of structural central nervous system anomalies, such as abnormalities in corpus callosum, heterotopias, ventriculomegaly, and hindbrain herniation, in both presurgical and postsurgical magnetic resonance images. Neurologic assessment was performed using the Pediatric Evaluation of Disability Inventory scale in children who were 12 months or older, covering 3 different sections, namely self-care, mobility, and social and cognitive function. RESULTS: A total of 46 fetuses were evaluated. Presurgery and postsurgery magnetic resonance imaging were performed at a median gestational age of 25.3 and 30.6 weeks, with a median interval of 0.8 weeks before surgery, and 4.0 weeks after surgery. There was a 70% reduction in hindbrain herniation (100% vs 32.6%; P<.001), and a normalization of the clivus supraocciput angle after surgery (55.3 [48.8-61.0] vs 79.9 [75.2-85.4]; P<.001). No significant increase in abnormal corpus callosum (50.0% vs 58.7%; P=.157) or heterotopia (10.8% vs 13.0%; P=.706) was observed. Ventricular dilation was higher after surgery (15.6 [12.7-18.1] vs 18.8 [13.7-22.9] mm; P<.001), with a higher proportion of severe ventricular dilation after surgery (≥15mm) (52.2% vs 67.4%; P=.020). Thirty-four children underwent neurologic assessment, with 50% presenting a global optimal Pediatric Evaluation of Disability Inventory result and 100% presenting a normal social and cognitive function. Children with optimal global Pediatric Evaluation of Disability Inventory presented a lower rate of presurgical anomalies in corpus callosum and severe ventriculomegaly. When analyzed as independent variables to global Pediatric Evaluation of Disability Inventory scale, the presence of abnormal corpus callosum and severe ventriculomegaly showed an odds ratio of 27.7 (P=.025; 95% confidence interval, 1.53-500.71) for a suboptimal result. CONCLUSION: Prenatal open spina bifida repair did not change the proportion of abnormal corpus callosum nor heterotopias after surgery. The combination of presurgical abnormal corpus callosum and severe ventricular dilation (≥15 mm) is associated with an increased risk of suboptimal neurodevelopment.

Prevalence of supratentorial anomalies assessed by magnetic resonance imaging in fetuses with open spina bifida.

OBJECTIVES: To determine the prevalence of brain anomalies at the time of preoperative magnetic resonance imaging (MRI) assessment in fetuses eligible for prenatal open spina bifida (OSB) repair, and to explore the relationship between brain abnormalities and features of the spinal defect. METHODS: This was a retrospective cross-sectional study, conducted in three fetal medicine centers, of fetuses eligible for OSB fetal surgery repair between January 2009 and December 2019. MRI images obtained as part of the presurgical assessment were re-evaluated by two independent observers, blinded to perinatal results, to assess: (1) the type and area of the defect and its anatomical level; (2) the presence of any structural central nervous system (CNS) anomaly and abnormal ventricular wall; and (3) fetal head and brain biometry. Binary regression analyses were performed and data were adjusted for type of defect, upper level of the lesion (ULL), gestational age (GA) at MRI and fetal medicine center. Multiple logistic regression analysis was performed in order to identify lesion characteristics and brain anomalies associated with a higher risk of presence of abnormal corpus callosum (CC) and/or heterotopia. RESULTS: Of 115 fetuses included, 91 had myelomeningocele and 24 had myeloschisis. Anatomical level of the lesion was thoracic in seven fetuses, L1-L2 in 13, L3-L5 in 68 and sacral in 27. Median GA at MRI was 24.7 (interquartile range, 23.0-25.7) weeks. Overall, 52.7% of cases had at least one additional brain anomaly. Specifically, abnormal CC was observed in 50.4% of cases and abnormality of the ventricular wall in 19.1%, of which 4.3% had nodular heterotopia. Factors associated independently with higher risk of abnormal CC and/or heterotopia were non-sacral ULL (odds ratio (OR), 0.51 (95% CI, 0.26-0.97); P = 0.043), larger ventricular width (per mm) (OR, 1.23 (95% CI, 1.07-1.43); P = 0.005) and presence of abnormal cavum septi pellucidi (OR, 3.76 (95% CI, 1.13-12.48); P = 0.031). CONCLUSIONS: Half of the fetuses assessed for OSB repair had an abnormal CC and/or an abnormal ventricular wall prior to prenatal repair. The likelihood of brain abnormalities was increased in cases with a non-sacral lesion and wider lateral ventricles. These findings highlight the importance of a detailed preoperative CNS evaluation of fetuses with OSB. © 2021 The Authors. Ultrasound in Obstetrics & Gynecology published by John Wiley & Sons Ltd on behalf of International Society of Ultrasound in Obstetrics and Gynecology.

Open intrauterine repair of spina bifida aperta: Historical aspects, current availability, and clinical outcomes from the Latin American Spina Bifida Consortium.

OBJECTIVE: To determine the historical aspects, current availability, and clinical outcomes of open intrauterine repair of spina bifida aperta (IRSBA) in Spanish-speaking Latin American countries. METHODS: Cases were collected from centers with at least 2 years of experience and a minimum of 10 open IRSBA interventions by December 2020. Clinical variables were compared to the results of the Management of Myelomeningocele Study (MOMS) trial. RESULTS: Clinical experience with 314 cases from seven centers was reviewed. Most cases (n = 189, 60.2%) were performed between 24 and 25.9 weeks' gestation. Delivery at less than 30 weeks' gestation occurred in 36 cases (11.5%) and the overall perinatal mortality rate was 5.4% (17 of 314). The rate of maternal complications was low, including the need for blood transfusion (n = 3, 0.9%) and dehiscence or a thin uterine scar (n = 4, 1.3%). No cases of maternal death were recorded. Fifteen neonates required additional surgical repair of the spinal defect (4.8%) and 63 of 167 infants (37.7%) required a cerebrospinal fluid diversion procedure. Only two of the seven centers reported preliminary experience with fetoscopic IRSBA. CONCLUSIONS: Clinical experience and outcomes were within the expected results reported by the MOMS trial. There is still very limited experience with fetoscopic IRSBA in this part of the world.

Incidence and patterns of abnormal corpus callosum in fetuses with isolated spina bifida aperta.

OBJECTIVE: To determine the incidence and characterise corpus callosum (CC) abnormalities in fetuses with spina bifida aperta (SBA) between 18 and 26 weeks of gestation. METHODS: This was a retrospective study on fetuses with isolated SBA and who were assessed for fetal surgery. Digitally stored ultrasound images of the brain were reviewed for the presence/absence of the CC, and the length and diameter of its constituent parts (rostrum, genu, body and splenium). We used regression analysis to determine the relationship between CC abnormalities and gestational age, head circumference, ventricle size, lesion level and lesion type. RESULTS: Nearly three-quarters of fetuses with isolated SBA had an abnormal CC (71.7%, 76/106). Partial agenesis was most common in the splenium (18.9%, 20/106) and the rostrum (13.2%, 14/106). The most common abnormal pattern was of a short CC with normal diameter throughout. Of note, 20.8% (22/106) had a hypoplastic genu and 28.3% (30/106) had a thick body part. Larger lateral ventricle size was associated with partial agenesis of the CC (odds ratio [OR]: 0.14, p < 0.001) and inversely associated with a shorter CC (OR: 2.60, p < 0.01). CONCLUSION: An abnormal CC is common in fetuses with isolated SBA who are referred for fetal surgery.

Detection of Spina Bifida by First Trimester Screening - Results of the Prospective Multicenter Berlin IT-Study.

Purpose To evaluate the potential of routine assessment of intracranial translucency (IT) and other posterior brain parameters in the early detection of open spina bifida during the 11 - 14 weeks screening examination. Materials and Methods This prospective, multicenter longitudinal study was conducted with the participation of 20 certified DEGUM II or III experts in Berlin, Germany, between June 2010 and October 2013. All pregnant women undergoing a first trimester screening were included in the study and in every patient were the IT, brain stem (BS), cisterna magna (CM), BS to occipital bone distance (BSOB) and BS/BSOB ratio measured. All patients with continuing pregnancy underwent a second trimester scan. Our data was used to develop our own reference ranges. The primary outcome parameter was the presence of open spina bifida. Results A total of 15 526 women with 16 164 fetuses were examined. Median of the IT was 2.1 mm, of the CM 1.6 mm, of the BS 2.7 mm, of the BSOB 5.5 mm, and of the BS/BSOB ratio 0.49. There were 11 cases with open spina bifida (incidence of 6.8/10 000). The detection rate was 100 % and in all cases of spina bifida, the anomaly was detected either at the first examination (n = 8) or considered suspicious and the lesion then detected a few weeks later (n = 3). Considering individual measurements, however, the detection rate was 18 % with the complete absence of the IT and 45 % with cut-off values. For the CM measurement, the detection rate was 64 % with the absence of the CM and 73 % with cut-off values. The other parameters proved not to be predictive of open spina bifida. Conclusion In the hands of an expert, open spina bifida can be reliably diagnosed early in gestation during the 11 - 14 weeks screening. The measurement of different parameters of the posterior brain, especially the CM and the use of cut-off values are of tremendous benefit in achieving a high sensitivity in the detection rate.

Epidemiology of congenital anomalies of the central nervous system in children in Enugu, Nigeria: A retrospective study.

BACKGROUND: Congenital anomalies, including those of the central nervous system (CNS), are among the leading causes of morbidity, mortality, and fetal loss. OBJECTIVE: To determine the prevalence and associated factors of CNS congenital anomalies in children. METHODS: A cross-sectional retrospective study of children managed with CNS anomalies was undertaken. Relevant clinical data of identified cases based on standard case definitions were retrieved from their case record files. Data were analyzed using SPSS 20.0 while the level of statistical significance was set at P < 0.05. RESULTS: Seventy-two cases of CNS anomalies were identified over the period under review; out of 7329 total pediatric admissions giving a prevalence of 0.98%. Spina bifida cystica, 49 (68.0%) was the most common of the five anomalies seen followed by congenital hydrocephalus 11 (15.3%). Fifty-seven (79.2%) of the mothers did not take periconceptional folic acid supplementation (P < 0.05) whereas 25 (34.7%), 6 (8.3%), and 1 (1.4%) reported history of febrile illness in the first trimester of pregnancy, alcohol use, and diabetes mellitus in pregnancy, respectively. Majority of the cases of spina bifida cystica (30 [61.2%]) seen had corrective surgeries while the overall case fatality rate was 1 (1.4%). CONCLUSIONS: Spina bifida cystica was the most common anomaly of the CNS seen in this study and majority of the mothers of affected children did not take periconceptional folic acid supplementation (P < 0.05). Efforts should be made to create awareness and apply adequate preventive health education models including the use of periconceptional folic acid supplementation as well as the provision of access to standard prenatal care to at risk mothers.

Prenatal diagnosis of open spina bifida in Emilia-Romagna.

OBJECTIVE: To report recent data on the epidemiology of pregnancies affected by open spina bifida in the Emilia-Romagna region of Italy. METHODS: All cases of open spina bifida diagnosed in the Emilia-Romagna region between 2001 and 2011 and reported to the IMER regional registry were included in the study group. The pregnancy outcome was retrospectively assessed. RESULTS: In the study period out of 390,978 babies born in Emilia-Romagna 126 cases of open spina bifida were reported to the IMER registry, resulting in a global prevalence of 3.2 per 10,000 births. Prenatal diagnosis was achieved in the vast majority of these cases (105/126; 83.3%) and in a great proportion of those women (85/105; 80.9%) who opted for termination of pregnancy. CONCLUSIONS: In a wide region of northern Italy where ultrasound anomaly scan is routinely offered to the general population, the vast majority of cases of open spina bifida are diagnosed antenatally and terminated electively.

Myelomeningocele (open spina bifida) - surgical management.

Myelomeningocele has been recognized since ancient times although written descriptions began not before the 17th century. Among all serious congenital malformations, myelomeningocele is unique that is has a steady and considerable prevalence while being compatible with life. It has a dismal prognosis when left untreated where virtually all die within the first year while aggressive treatment have a profound effect on survival and quality of life. Effective surgical treatment became possible parallel to the treatment of hydrocephalus in the late 1950s. Advent of the shunt systems undoubtedly changed the morbidity and mortality rates due to associated hydrocephalus. Aggressive and effective treatment improved survival rates but also those suffering physical and mental disabilities have increased as well. Ethical and socioeconomic concerns have led to proposal for selective treatment criteria which have raised arguments on medical and ethico-legal rounds. After the swing of the pendulum between early treatment in all affected children and selective treatment of those who fulfilled the criteria for good prognosis, early myelomeningocele repair is practiced widely unless the infant is critically ill.Incidence of myelomeningocele has been decreasing especially in the Western world, partly due to prenatal diagnosis and elective terminations, dietary folate supplementation. Still, it is the most common central nervous system malformation and one of the leading causes of paraplegia, worldwide. Unfortunately, gains in the management of myelomeningocele have been mainly on antenatal diagnosis and prevention while efforts on understanding its cause, mechanisms involved are still tentative. Concerning the surgical management, no revolutionary modification improving outcome has been introduced unlike other fields of neurosurgery.Medical management of a child with myelomeningocele requires a lifelong effort of several disciplines including urology, orthopedics physical and social therapy besides neurosurgery. The initial and probably the most crucial step begin with proper repair of the lesion. The aim of surgery, with its simplest definition should be towards maintaining the medical condition of the newborn. In other words, consequences of an open spinal cord segment with associated malformations have to be avoided with appropriate measures. Comparable to the surgical treatment of any congenital malformation, myelomeningocele repair consist of reversing the failed steps of normal neural tube closure. This requires a thorough understanding of the normal and abnormal embryological sequence of events in formation of the spinal cord. Although the purpose of this chapter is to describe the basic concepts and technique of myelomeningocele repair, contemporary information and progress on epidemiology, and etiology and embryology is presented with discussion of controversial issues regarding the selection process, optimal time for surgery and technical modifications.

Potential association between infertility and spinal neural tube defects in offspring.

BACKGROUND: We examined the possible association between infertility and spinal neural tube defects (NTDs). METHODS: This is a nested case-control study within the Kaiser Permanente Medical Care Program (KPMCP) in Northern California. Among a birth cohort of 110,624 singleton infants > or = 36 weeks gestation, 1994-1997, we electronically identified cases of spinal NTDs and confirmed the diagnosis by chart review. Controls (n = 1,608) were randomly selected from the birth population. History of infertility was defined as: (1) physician diagnosis of infertility; (2) prescription for an infertility medication noted in the KPMCP pharmacy; and/or (3) evaluation at 1 of 15 infertility clinics in Northern California. RESULTS: Eighteen infants diagnosed with spinal NTDs (prevalence 1.6/10,000) included 13 with spina bifida cystica and 5 with spina bifida occulta. Case mothers were more likely to have a history of infertility (4/18 vs. 96/1,608, OR 4.3, 95% CI 1.01-14.0), and to have been prescribed clomiphene citrate within the window spanning 60 days before to 15 days after conception (3/18 vs. 32/1,608, OR 11.7, 95% CI 2.0-44.8). CONCLUSION: This exploratory study suggests that infertility may be associated with an increased risk of spinal NTDs among liveborn, term infants.

Pattern and factors affecting management outcome of spina bifida cystica in Ile-Ife, Nigeria.

BACKGROUND AND OBJECTIVE: There is paucity of data on the pattern and factors affecting the management outcome of patients with spina bifida cystica in the Ife-Ijesa zone, Nigeria. This study was designed to address this research question. METHOD: One hundred and six consecutive cases of spina bifida cystica who presented in our hospital from January 1990 to December 2004 were reviewed. We obtained information on sociodemographic factors, medical history and management as well as clinical outcome. SPSS was used to analyze the data. RESULT: Males constituted 54.7% and females 45.2% of cases. Mortality was high in those presented after the 4th week of life (p = 0.04). The malformation occurred in the lumbar and lumbosacral regions in 77.4%. Myelomeningocele was the most common type (86.8%). Hydrocephalus was recorded in 53.8% of patients. Surgical closure was done for 91.5% of the patients. About 77% of all the patients were discharged while 22.7% died. This was significantly related to age at presentation (p = 0.04) and infection before surgery (p = 0.045). Postoperative complications were more frequent in patients with ruptured lesions (p = 0.025), a larger size of defect (p = 0.028) and a lower birth weight (p = 0.006). CONCLUSION: Myelomeningocele is the most common type of spina bifida cystica in our environment. Late presentation and preoperative infection are associated with high mortality in our patients.

Dermatoglyphics of mothers of Malawian children with spina bifida cystica: a comparative study with female controls.

UNLABELLED: Dermatoglyphic traits are formed under genetic control early in development and do not change thereafter, thus maintaining stability not affected by age. METHODOLOGY: We determined the dermatoglyphic traits of mothers of children with spina bifida cystica and compared then with controls matched for number, age and parity, by counting and classifying palmar, plantar and digital ridge pattern configurations of arches, loops, whorls and ridges based on standard techniques. RESULTS: Palmar pattern types, showed absence of arches, significantly higher frequency of whorls (P > 0.05), lower total finger ridge count (TFRC) and higher Pattern Intensity Index (PII) in these mothers than in the controls (P > 0.001). However, no significant differences were observed between both groups in atd angle and a-b ridge count (P = 130, 0.70 respectively). Plantar pattern types showed loops restricted to the first two digits and absence of arches in the first digit in these mothers compared to controls in whom there were loops in the first four digits and a 100% frequency of arches. Similarly, PII was higher and Dankmeijer's Index (DI) lower in these mothers than in controls. CONCLUSION: Our findings demonstrate dermatoglyphic differences between both groups that suggest that mothers presenting with these traits are more predisposed to giving birth to children with spina bifida cystica.

Prevalence of aneuploidy and additional anatomic abnormalities in fetuses with open spina bifida: population based study in Utah.

Data were used to determine the population prevalence of aneuploidy and additional anatomic abnormalities in fetuses with open spina bifida. The ability of sonography to predict aneuploidy and identify additional anatomic abnormalities in euploid fetuses was assessed. All cases of spina bifida occurring in the state of Utah from 1995 through 1997 were reviewed using Utah Birth Defect Network data, including stillborn, liveborn, and terminated cases. Chromosomes were known in 45 of 51 cases of open spina bifida. Of the 45 fetuses, 6 (13%) were aneuploid. Major anatomic abnormalities were present in four of six (67%) cases, and two of six (33%) cases had additional anomalies that could be missed sonographically. Of 39 euploid fetuses, 12 (31%) had additional abnormalities, but only half likely would be detected sonographically. Our 4% risk of aneuploidy in sonographically isolated spina bifida is substantially higher than the risk associated with advanced maternal age (0.37%).

Neural tube defects along the Texas-Mexico border, 1993-1995.

In response to a 1991 anencephaly cluster in Cameron County, Texas, a surveillance and neural tube defect (NTD) recurrence prevention project for NTDs was implemented in the 14 Texas-Mexico border counties. For 1993-1995, NTD-affected pregnancies were identified at all gestational ages through active surveillance of multiple case-ascertainment sources. There were 87 cases of anencephaly, 96 cases of spina bifida, and 14 cases of encephalocele for respective rates of 6.4, 7.1, and 1.1 per 10,000 live births. Of the 197 NTD case-women, 93% were Hispanic. The overall, Hispanic, and Anglo NTD rates were, respectively, 14.6, 14.9, and 10.6 per 10,000 live births. The NTD rate for El Paso County (9.8 per 10,000), the most northwestern Texas county, was significantly lower (p = 0.001) than the aggregate rate for the rest of the Texas border (17.1 per 10,000). The overall Texas border rate was significantly higher (p < 0.001) than a recently estimated rate of 9.3 for California and minimally higher than a recently adjusted rate of 11.3 for the Metropolitan Atlanta Congenital Defects Program counties (p = 0.052), both of which now reflect all gestational ages. Of the 197 Texas border cases, 85% (168 cases) reached a gestational age of > or =20 weeks. Excluding cases of <20 weeks' gestation in the rate had a more marked effect on reducing the anencephaly rate (4.9 per 10,000) than the spina bifida rate (6.7 per 10,000). A country of birth was known for 153 (83%) of the 184 Hispanic case-women: 63% were born in Mexico; 24%, in Texas; and 11%, elsewhere in the United States. Rates for Mexico-born Hispanic women (15.1 per 10,000) were significantly higher than rates for United States-born Hispanic women (9.5 per 10,000) (p = 0.006).

Paternal occupational exposure around conception and spina bifida in offspring.

A multi-center case-referent study was conducted on the relation between paternal occupational exposure and spina bifida in offspring. Cases were born between 1980 and 1992 in The Netherlands. Referents were recruited from hospitals and from the general population. Postal questionnaires were used to gather information on occupation and potential confounders. Through job-specific telephone interviews with 122 case fathers and 411 referent fathers, detailed exposure information was collected on specific tasks, the use of chemical or physical agents, frequency of exposure, and use of protective equipment. The study yielded statistically significant associations between spina bifida and low exposure to welding fumes (OR = 1.6, 95% CI: 1.0-2.6) and low exposure to UV radiation during welding (OR = 2.6, 95% CI: 1.2-5.6), and suggestive findings of an association between spina bifida and moderate or high exposure to cleaning agents, moderate or high pesticide exposure (OR = 1.7, 95% CI: 0.7-4.0), and stainless steel dust (OR = 2.0, 95% CI: 0.8-5.2). No associations were identified for other paternal occupational exposures, such as organic solvents.

Spina bifida and parental occupation.

To examine the association between parental occupation and spina bifida in offspring, we conducted a multicenter case-referent study in the Netherlands. Cases were children with spina bifida aperta from nine different hospitals throughout the country; the referent group comprised population-based referents who were randomly drawn from municipal birth registries. All children were born between 1980 and 1992. We collected data using postal questionnaires for both parents with questions about occupational title, industry, daily occupational activities, and a number of potential confounders. We were able to include 353 cases and 1,329 referents in the analyses. We found increased risks for maternal agricultural occupations [odds ratio (OR) = 5.6; 95% confidence interval (CI) = 1.8-17.8] and for cleaning women (OR = 1.9; 95% CI = 0.9-3.9). For the fathers, we saw increased odds ratios for welders (OR = 2.1; 95% CI = 0.6-7.0) and transport workers (OR = 1.4; 95% CI = 0.9-2.1).

[A five years surveillance on neural system birth defects in rural areas of China].

A total number of 167,274 births were observed on birth defects in rural areas 1968-1990 in China. The results showed that there were 361 cases of neural system defects, accounting for 31.45% in all birth defects. The incidence of neural system defects was 2.19% with hydrocephalus, anencephalus and spinal bifida 0.89%, 0.87%, 0.36% respectively. The distribution of neural system birth defects showed that incidence in northern part of the country was higher than that of in the south while in winter--spring was higher than in summer--autumn. Results of unconditional logistic regression analysis demonstrated that risk factors were related to neural system defects as maternal education level, parity, delivery mode and lower birth weight.