How valid are the rates of Down syndrome internationally? Findings from the International Clearinghouse for Birth Defects Surveillance and Research

Epidemiology of neural tube defects in Finland: a nationwide register study 1987-2018

BACKGROUND

Our aim was to evaluate the prevalence, mortality, regional and sex distribution of neural tube defects (NTDs) in Finland.

METHODS

Data for this population-based study were collected from 1987 to 2018 from the national health and social welfare registers.

RESULTS

There were in total 1634 cases of NTDs, of which 511 were live births, 72 pregnancies ended in stillbirth and 1051 were terminations of pregnancy due to fetal anomaly (TOPFA). The total prevalence of NTDs was 8.6 per 10 000 births and it increased slightly annually (OR 1.008; 95% CI: 1.002, 1.013) during the 32-year study period. The birth prevalence of NTDs decreased (OR 0.979; 95% CI: 0.970, 0.987), but the prevalence of TOPFA increased annually (OR 1.024; 95% CI 1.017, 1.031). The perinatal mortality of NTD children was 260.7 per 1000 births and the infant mortality was 184.0 per 1000 live births, whereas these measures in the general population were 4.6 per 1000 births and 3.3 per 1000 live births, respectively. There was no difference in the NTD prevalence between males and females (P-value 0.77). The total prevalence of NTDs varied from 7.1 to 9.4 per 10 000 births in Finland by region.

CONCLUSIONS

Although the majority of NTDs are preventable with an adequate folic acid supplementation, the total prevalence increased in Finland during the study period when folic acid supplementation was mainly recommended to high-risk families and to women with folic acid deficiency. NTDs remain an important cause of infant morbidity and mortality in Finland.

Maternal risk factors for congenital vertebral formation and mixed defects: A population-based case-control study

Background

The etiology and risk factors of congenital vertebral anomalies are mainly unclear in isolated cases. Also, there are no reports on the risk factors for different subgroups of vertebral anomalies. Therefore, we assessed and identified potential maternal risk factors for these anomalies and hypothesized that diabetes, other chronic diseases, smoking, obesity, and medication in early pregnancy would increase the risk of congenital vertebral anomalies.

Methods

All cases with congenital vertebral anomalies were identified in the Finnish Register of Congenital Malformations from 1997 to 2016 for this nationwide register-based case-control study. Five matched controls without vertebral malformations were randomly selected. Analyzed maternal risk factors included maternal age, body mass index, parity, smoking, history of miscarriages, chronic diseases, and prescription drug purchases in early pregnancy.

Results

The register search identified 256 cases with congenital vertebral malformations. After excluding 66 syndromic cases, 190 non-syndromic malformations (74 formation defects, 4 segmentation defects, and 112 mixed anomalies) were included in the study. Maternal smoking was a significant risk factor for formation defects (adjusted odds ratio 2.33, 95% confidence interval 1.21-4.47). Also, pregestational diabetes (adjusted odds ratio 8.53, 95% confidence interval 2.33-31.20) and rheumatoid arthritis (adjusted odds ratio 13.19, 95% confidence interval 1.31-132.95) were associated with mixed vertebral anomalies.

Conclusion

Maternal pregestational diabetes and rheumatoid arthritis were associated with an increased risk of mixed vertebral anomalies. Maternal smoking increases the risk of formation defects and represents an avoidable risk factor for congenital scoliosis.

Level of evidence

III.

Gestational diabetes is associated with the risk of offspring's congenital anomalies: a register-based cohort study

BACKGROUND

Gestational diabetes mellitus (GDM) is a common pregnancy-related disorder and a well-known risk factor for adverse pregnancy outcomes. There are conflicting findings on the association of GDM with the risk of congenital anomalies (CAs) in offspring. In this study, we aimed to determine study whether maternal GDM is associated with an increased risk of major CAs in offspring.

METHODS

This Finnish Gestational Diabetes (FinnGeDi) register-based study included 6,597 women with singleton pregnancies and a diagnosis of GDM and 51,981 singleton controls with no diabetes identified from the Finnish Medical Birth Register (MBR) in 2009. Data from MBR were combined in this study with the Register of Congenital Malformations, which includes the data of CAs. We used logistic regression to calculate odds ratios (OR) for CAs, together with their 95% confidence intervals (CIs), adjusting for maternal age, parity, pre-pregnancy body mass index (BMI), and maternal smoking status.

RESULTS

The risk of major CAs was higher in the GDM-exposed (n = 336, 5.09%) than in the non-exposed group (n = 2,255, 4.33%) (OR: 1.18, 95% CI: 1.05-1.33, p = 0.005). The adjusted OR (aOR) was 1.14 (95% CI: 1.00-1.30, p = 0.047). There was a higher overall prevalence of CAs, particularly chromosomal abnormalities (0.52% vs. 0.21%), in the GDM-exposed group (OR: 2.49, 95% Cl: 1.69-3.66, p < 0.001). The aOR was 1.93 (95% Cl: 1.25-2.99, p = 0.003).

CONCLUSIONS

Offspring exposed to GDM have a higher prevalence of major CAs. Of note, risk factors other than GDM, such as older maternal age and a higher pre-pregnancy BMI, diminished the between group differences in the prevalence of major CAs. Nevertheless, our findings suggest that offspring exposed to maternal GDM are more likely to be diagnosed with a chromosomal abnormality, independent of maternal age, parity, pre-pregnancy BMI, and smoking.

Maternal Risk Factors for Congenital Vertebral Anomalies: A Population-Based Study

BACKGROUND

The spectrum of congenital vertebral defects varies from benign lesions to severe, life-threatening conditions. The etiology and maternal risk factors remain mainly unclear in isolated cases. Hence, we aimed to assess and identify potential maternal risk factors for these anomalies. Based on previous studies, we hypothesized that maternal diabetes, smoking, advanced maternal age, obesity, chronic diseases, and medication used during the first trimester of pregnancy might increase the risk of congenital vertebral malformations.

METHODS

We performed a nationwide register-based case-control study. All cases with vertebral anomalies (including live births, stillbirths, and terminations for fetal anomaly) were identified in the Finnish Register of Congenital Malformations from 1997 to 2016. Five matched controls from the same geographic region were randomly selected for each case. Analyzed maternal risk factors included age, body mass index (BMI), parity, smoking, history of miscarriages, chronic diseases, and prescription drugs dispensed during the first trimester of pregnancy.

RESULTS

In total, 256 cases with diagnosed congenital vertebral anomalies were identified. After excluding 66 malformations associated with known syndromes, 190 nonsyndromic malformation cases were included. These were compared with 950 matched controls. Maternal pregestational diabetes was a significant risk factor for congenital vertebral anomalies (adjusted odds ratio [OR], 7.30 [95% confidence interval (CI), 2.53 to 21.09). Also, rheumatoid arthritis (adjusted OR, 22.91 [95% CI, 2.67 to 196.40]), estrogens (adjusted OR, 5.30 [95% CI, 1.57 to 17.8]), and heparins (adjusted OR, 8.94 [95% CI, 1.38 to 57.9]) were associated with elevated risk. In a sensitivity analysis using imputation, maternal smoking was also significantly associated with an elevated risk (adjusted OR, 1.57 [95% CI, 1.05 to 2.34]).

CONCLUSIONS

Maternal pregestational diabetes and rheumatoid arthritis increased the risk of congenital vertebral anomalies. Also, estrogens and heparins, both of which are frequently used in assisted reproductive technologies, were associated with an increased risk. Sensitivity analysis suggested an increased risk of vertebral anomalies with maternal smoking, warranting further studies.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Increasing Prevalence and High Risk of Associated Anomalies in Congenital Vertebral Defects: A Population-based Study

BACKGROUND

Congenital vertebral anomalies are a heterogeneous group of diagnoses, and studies on their epidemiology are sparse. Our aim was to investigate the national prevalence and mortality of these anomalies, and to identify associated anomalies.

METHODS

We conducted a population-based nationwide register study and identified all cases with congenital vertebral anomalies in the Finnish Register of Congenital Malformations from 1997 to 2016 including live births, stillbirths, and elective terminations of pregnancy because of major fetal anomalies. Cases were categorized based on the recorded diagnoses, associated major anomalies were analyzed, and prevalence and infant mortality were calculated.

RESULTS

We identified 255 cases of congenital vertebral anomalies. Of these, 92 (36%) were diagnosed with formation defects, 18 (7.1%) with segmentation defects, and 145 (57%) had mixed vertebral anomalies. Live birth prevalence was 1.89 per 10,000, and total prevalence was 2.20/10,000, with a significantly increasing trend over time (P<0.001). Overall infant mortality was 8.2% (18/219); 3.5% (3/86) in patients with formation defects, 5.6% (1/18) in segmentation defects, and 12.2% (14/115) in mixed vertebral anomalies (P=0.06). Co-occurring anomalies and syndromes were associated with increased mortality, P=0.006. Majority of the cases (82%) were associated with other major anomalies affecting most often the heart, limbs, and digestive system.

CONCLUSIONS

In conclusion, the prevalence of congenital vertebral anomalies is increasing significantly in Finnish registers. Detailed and systematic examination is warranted in this patient population to identify underlying comorbidities as the majority of cases are associated with congenital major anomalies.

LEVEL OF EVIDENCE

Level III.

Prune belly syndrome in Finland - A population-based study on current epidemiology and hospital admissions

BACKGROUND

Prune belly syndrome (PBS) is a multisystem disease characterized by absent or deficient abdominal musculature with accompanying lax skin, urinary tract abnormalities, and cryptorchidism. Previous studies have estimated a birth prevalence of 1 in 35,000-50,000 live births.

OBJECTIVE

We set out to clarify the epidemiology and early hospital admissions of PBS in Finland through a population-based register study. Further, possible maternal risk factors for PBS were analyzed in a case-control setting.

STUDY DESIGN

The Finnish Register of Congenital Malformations was linked to the Care Register for Health Care, a population-based hospital admission data for PBS patients. Additionally, five matched controls were identified in the Birth Register and maternal risk factors of PBS were studied utilizing data from the Drugs and Pregnancy database.

RESULTS

We identified 31 cases of PBS during 1993-2015, 15 of which were live born and 16 elective terminations. The total prevalence was 1 in 44,000 births. Three patients (20%) died during infancy. On average, PBS-patients had 3.2 admissions and 10.6 hospital days per year in Finland during the study period years 1998-2015, 35- and 27-fold compared to children in Finland in general. Multiple miscarriages were significantly associated to PBS in maternal risk factor analyses.

DISCUSSION

The burden of disease is significant in PBS, demonstrated as a high infant mortality rate (20%), multiple hospital admissions, and inpatient care in days. The available variables are limited as a register-based study.

CONCLUSION

We present data on contemporary epidemiology in a population-based study and show that the total prevalence of PBS is 1 in 44,000 in Finland. PBS entails a significant disease burden with admissions and hospital days over 35- and 27-fold compared to the general pediatric population, further aggravated by an infant mortality rate of 20%.

Maternal risk factors for congenital limb deficiencies: A population-based case-control study

BACKGROUND

Risk factors for congenital limb deficiencies are poorly understood.

OBJECTIVE

To investigate risk factors for congenital limb deficiencies.

METHODS

We conducted a nationwide population-based case-control (1:5) study in Finland, using national registers on congenital anomalies, births, and induced abortions, cross-linked with data on maternal prescription medicine use obtained from the registers on Reimbursed Drug Purchases and Medical Special Reimbursements. Five hundred and four children with limb deficiencies (241 isolated, 181 syndromic, and 82 other associated anomalies) were identified, and 2,520 controls were matched to cases on residence and year of pregnancy. Non-syndromic cases (n = 323) were subdivided into longitudinal (n = 120), transverse (n = 123), intercalary (n = 24), mixed (n = 18), and unknown (n = 38) deficiencies.

RESULTS

Pregestational diabetes was associated with all limb deficiencies (adjusted odds ratio [OR] 12.71, 95% confidence interval [CI] 2.37, 68.25) and with isolated (OR 11.42, 95% CI 2.00, 64.60) deficiencies. Primiparity was associated with increased risk of congenital limb deficiencies among all cases (OR 1.49, 95% CI 1.15, 1.93), isolated cases (OR 1.46, 95% CI 1.09, 1.96), and among cases with longitudinal (OR 1.90, 95% CI 1.24, 2.90) and transverse deficiencies (OR 1.75, 95% CI 1.13, 2.70). Young maternal age (<25 years) was associated with all congenital limb deficiencies (OR 1.40, 95% CI 1.02, 1.90) and transverse deficiencies (OR 1.76, 95% CI 1.05, 2.96). Advanced maternal age (≥35 years) was associated with syndromic (OR 1.82, 95% CI 1.19, 2.78) and transverse deficiencies (OR 1.94, 95% CI 1.06, 3.57). Maternal antiepileptic medication was associated with all (OR 5.77, 95% CI 1.75, 19.04) and with isolated cases (OR 3.83, 95% CI 1.02, 14.34).

CONCLUSIONS

It is important that pregnant women taking medications, especially antiepileptics, or women with pregestational diabetes are carefully monitored with regard to the occurrence and risk of limb deficiencies in the fetus.

Congenital abdominal wall defects and cryptorchidism: a population-based study

PURPOSE

Several studies have reported high prevalence of undescended testis (UDT) among boys with congenital abdominal wall defects (AWD). Due to rarity of AWDs, however, true prevalence of testicular maldescent among these boys is not known. We conducted a national register study to determine the prevalence of UDT among Finnish males with an AWD.

METHODS

All male infants with either gastroschisis or omphalocele born between Jan 1, 1998 and Dec 31, 2015 were identified in the Register of Congenital Malformations. The data on all performed operations were acquired from the Care Register for Health Care. The register data were examined for relevant UDT diagnosis and operation codes.

RESULTS

We identified 99 males with gastroschisis and 89 with omphalocele. UDT was diagnosed in 10 (10.1%) infants with gastroschisis and 22 (24.7%) with omphalocele. Majority of these required an operation; 8/99 (8.1%) gastroschisis and 19/89 (21.3%) omphalocele patients. UDT is more common among AWD patients than general population with the highest prevalence in omphalocele.

CONCLUSIONS

Cryptorchidism is more common among boys with an AWD than general population. Furthermore, omphalocele carries significantly higher risk of UDT and need for orchidopexy than gastroschisis. Due to high prevalence testicular maldescent, careful follow-up for UDT is recommended.

Risk Factors and Prevalence of Limb Deficiencies Associated With Amniotic Band Sequence: A Population-based Case-control Study

BACKGROUND

Limb deficiencies associated with amniotic bands comprise a wide range of congenital anomalies. The association of maternal medication and the risk of amniotic band sequence (ABS) has not yet been addressed.

METHODS

This nationwide population-based case-control study used national registers on congenital anomalies, births and induced abortions, cross-linked with information on maternal prescription medicine use obtained from the registers on Reimbursed Drug Purchases and Medical Special Reimbursements. All cases with congenital limb deficiency associated with amniotic bands born between 1996 and 2008 were included in the study. Five controls without limb deficiency matched for residency and time of conception were randomly selected from the Medical Birth Register.

RESULTS

In total, 106 children with limb deficiency associated with ABS were identified and compared with 530 matched controls. Young maternal age (less than 25 y) increased the risk of limb deficiencies [odds ratio=1.72; 95% confidence interval (CI): 1.06, 2.80]. Primiparity was also associated with increased risk [adjusted odds ratio (aOR)=2.42; 95% CI: 1.52, 3.88]. After adjusting for maternal age, pregestational diabetes, and parity, maternal use of beta-blockers (adjusted OR=24.2; 95% CI: 2.57, 228) and progestogens (adjusted OR=3.79; 95% CI: 1.38, 10.4) during the first trimester of pregnancy significantly increased the risk of limb deficiencies associated with amniotic bands.

CONCLUSIONS

Primiparity significantly increased the risk of limb defects associated with amniotic bands. Also, a novel association on increased risk of ABS with maternal use of progestogens or beta-blockers during the first trimester of pregnancy was observed.

LEVEL OF EVIDENCE

Level III.

Long-term hospital admissions and surgical treatment of children with congenital abdominal wall defects: a population-based study

Congenital abdominal wall defects, namely, gastroschisis and omphalocele, are rare congenital malformations with significant morbidity. The long-term burden of these anomalies to families and health care providers has not previously been assessed. We aimed to determine the need for hospital admissions and the requirement for surgery after initial admission at birth. For our analyses, we identified all infants with either gastroschisis (n=178) or omphalocele (n=150) born between Jan 1, 1998, and Dec 31, 2014, in the Register of Congenital Malformations. The data on all hospital admissions and operations performed were acquired from the Finnish Hospital Discharge Register between Jan 1, 1998, and Dec 31, 2015, and compared to data on the whole Finnish pediatric population (0.9 million) live born 1993-2008. Patients with gastroschisis and particularly those with omphalocele required hospital admissions 1.8 to 5.7 times more than the general pediatric population (p<0.0001). Surgical interventions were more common among omphalocele than gastroschisis patients (p=0.013). At the mean follow-up of 8.9 (range 1.0-18.0) years, 29% (51/178) of gastroschisis and 30% (45/150) of omphalocele patients required further abdominal surgery after discharge from the neonatal admission.Conclusion: Patients with gastroschisis and especially those with omphalocele, are significantly more likely than the general pediatric population to require hospital care. Nevertheless, almost half of the patients can be treated without further surgery, and redo abdominal surgery is only required in a third of these children. What is Known: • Gastroschisis and omphalocele are congenital malformations with significant morbidity • There are no reports on the long-term need for hospital admissions and surgery in these children What is New: • Patients with abdominal wall defects are significantly more likely than the general pediatric population to require hospital care • Almost half of the patients can be treated without further surgery, and abdominal redo operations are only required in a third of these children.

High incidence of inguinal hernias among patients with congenital abdominal wall defects: a population-based case-control study

The aim of this nationwide population-based case-control study was to assess the incidence of inguinal hernia (IH) among patients with congenital abdominal wall defects. All infants born with congenital abdominal wall defects between Jan 1, 1998, and Dec 31, 2014, were identified in the Finnish Register of Congenital Malformations. Six controls matched for gestational age, sex, and year of birth were selected for each case in the Medical Birth Register. The Finnish Hospital Discharge Register was searched for relevant diagnosis codes for IH, and hernia incidence was compared between cases and controls. We identified 178 infants with gastroschisis and 150 with omphalocele and selected randomly 1968 matched, healthy controls for comparison. Incidence of IH was significantly higher in gastroschisis girls than in matched controls, relative risk (RR) 7.20 (95% confidence interval [CI] 2.25-23.07). In boys with gastroschisis, no statistically significant difference was observed, RR 1.60 (95% CI 0.75-3.38). Omphalocele was associated with higher risk of IH compared to matched controls, RR 6.46 (95% CI 3.90-10.71), and the risk was equally elevated in male and female patients.Conclusion: Risk of IH is significantly higher among patients with congenital abdominal wall defects than in healthy controls supporting hypothesis that elevated intra-abdominal pressure could prevent natural closure of processus vaginalis. Parents should be informed of this elevated hernia risk to avoid delays in seeking care. We also recommend careful follow-up during the first months of life as most of these hernias are diagnosed early in life. What is Known: • Inguinal hernia is one of the most common disorders encountered by a pediatric surgeon. • Prematurity increases the risk of inguinal hernia. What is New: • Children with congenital abdominal wall defects have a significantly higher risk of inguinal hernia than general population. • Families should be informed of this elevated hernia risk to avoid delays in seeking care.

Prevalence and risk factors of radial ray deficiencies: A population-based case-control study

Radial ray deficiency is the most common congenital deficiency of the upper limb. The aim of our study was to investigate maternal risk factors for radial ray deficiencies. We conducted a nationwide population-based case-control study using national registers. All cases with a radial ray deficiency born between 1996 and 2008 were included in the study and compared with five controls without limb deficiency. In total, 115 (10 isolated, 18 with multiple congenital anomalies, and 87 syndromic) cases with radial ray deficiencies were identified and compared with 575 matched controls. The total prevalence in Finland was 1.22 per 10,000 births. No significant risk factors were observed for nonsyndromic cases. In the syndromic group, advanced maternal age (≥35 years) increased the risk of radial aplasia (aOR 2.45, 95% CI 1.37-4.36), and a similar association was observed with multiple pregnancy (aOR 2.97, 1.16-7.62) and male sex (aOR 1.96, 1.18-3.25). Valproic acid was also a risk factor (p = .002). In conclusion, novel associations in the syndromic group of advanced maternal age and multiple pregnancy and increased risk of radial ray deficiencies were observed. Also, early reports on increased risk of RRD associated with valproate and male sex were supported by our results.

The reduced use of invasive procedures leads to a change of frequencies of prenatally detected chromosomal aberrations: population data from the years 2012-2016

OBJECTIVE

The aim of the study was to analyze the results of screening for chromosomal aberrations in a population with a high rate of first-trimester screening and low rate of cell-free DNA testing.

METHODS

The data were obtained from the National Registry of Congenital Anomalies of the Czech Republic. We calculated and compared the proportion of autosomal trisomies (Down, Edwards, and Patau syndrome) and of other chromosomal aberrations identified during prenatal diagnostics.

RESULTS

We identified 3009 prenatally diagnosed cases of chromosomal aberrations in the 2012-2016 period. The number of major autosomal trisomies has increased from 329 cases (30.86 per 10,000 live births) in 2012 to 423 cases (37.41) in 2016 (p = 0.014). The numbers of other aberrations decreased from 246 cases (23.07 per 10,000) in 2012 to 217 cases (19.19) in 2016 (p = 0.017). The usage of invasive diagnostic procedures decreased from 1099.54 in 2012 to 622.73 in 2016 (per 10,000 live births).

CONCLUSIONS

Our population-based study confirmed a decrease in prenatal detection of nonmajor chromosomal aberrations wherein a decrease of invasive testing occurred. With the introduction of cell-free DNA testing, further decrease of invasive procedures and detection of nonmajor aberrations may be expected.

Trisomy 13 and 18-Prevalence and mortality-A multi-registry population based analysis

The aim of the study is to determine the prevalence, outcomes, and survival (among live births [LB]), in pregnancies diagnosed with trisomy 13 (T13) and 18 (T18), by congenital anomaly register and region. Twenty-four population- and hospital-based birth defects surveillance registers from 18 countries, contributed data on T13 and T18 between 1974 and 2014 using a common data-reporting protocol. The mean total birth prevalence (i.e., LB, stillbirths, and elective termination of pregnancy for fetal anomalies [ETOPFA]) in the registers with ETOPFA (n = 15) for T13 was 1.68 (95% CI 1.3-2.06), and for T18 was 4.08 (95% CI 3.01-5.15), per 10,000 births. The prevalence varied among the various registers. The mean prevalence among LB in all registers for T13 was 0.55 (95%CI 0.38-0.72), and for T18 was 1.07 (95% CI 0.77-1.38), per 10,000 births. The median mortality in the first week of life was 48% for T13 and 42% for T18, across all registers, half of which occurred on the first day of life. Across 16 registers with complete 1-year follow-up, mortality in first year of life was 87% for T13 and 88% for T18. This study provides an international perspective on prevalence and mortality of T13 and T18. Overall outcomes and survival among LB were poor with about half of live born infants not surviving first week of life; nevertheless about 10% survived the first year of life. Prevalence and outcomes varied by country and termination policies. The study highlights the variation in screening, data collection, and reporting practices for these conditions.

Birth prevalence of Down syndrome in Argentina

The aim of this study was to describe the prevalence at birth of Down syndrome in Argentina. The prevalence by jurisdiction and maternal age was calculated for the 2009-2015 period and the prevalence and proportion of prenatal diagnosis was compared according to sub-sector (public and private) and complexity level of the maternity wards. The association of Down syndrome with birth weight and gestational age was analyzed. The data source was the National Network of Congenital Anomalies of Argentina [Red Nacional de Anomalías Congénitas] (RENAC). The prevalence was 17.26 per 10,000 births; by jurisdictions it varied between 10.99 and 23.71; and by maternal age, between 10.32 in women <20 years of age and 158.06 in those ≥45 years of age. In hospitals of the private subsector there was a higher prevalence, attributable to differences in the structure of maternal age, and a greater proportion of prenatal diagnosis. There was a negative correlation between birth weight and Down syndrome (ß=-294.7; p<0.001). No difference in the median gestational age at birth between Down syndrome newborns and newborns without major anomalies was found, but the distribution of gestational age differed. Knowledge of certain epidemiological characteristics of this health issue could contribute to the implementation of health policies.

A proposal for the systematic assessment of data quality indicators in birth defects surveillance

BACKGROUND

Quality control and improvement are a key part of the implementation of an effective surveillance program. Data quality indicators (DQI) are key tools but have not been widely used, especially in a low-resource setting.

METHODS

We developed a list of data quality indicators of birth defects surveillance. These DQI address ascertainment, description, coding, and classification.

RESULTS

We developed 40 DQI that can be used widely to assess the quality of data relative to birth defects of major clinical and public health impact.

CONCLUSIONS

DQI have to be both comprehensive (e.g., assess all main surveillance processes) and practical (not require sophisticated or costly data elements), so that they can be used effectively in many different settings. We propose this list of DQI for use in surveillance program as a way to document the quality of the program; detect variations within and between programs, and support quality improvements.

Chromosomal disorders: estimating baseline birth prevalence and pregnancy outcomes worldwide

Chromosomal disorders, of which Down syndrome is the most common, can cause multi-domain disability. In addition, compared to the general population, there is a higher frequency of death before the age of five. In many settings, large gaps in data availability have hampered policy-making, programme priorities and resource allocation for these important conditions. We have developed methods, which overcome this lack of data and allow estimation of the burden of affected pregnancies and their outcomes in different settings worldwide. For example, the methods include a simple equation relating the percentage of mothers 35 and over to Down syndrome birth prevalence. The results obtained provide a starting point for consideration of services that can be implemented for the care and prevention of these disorders.

Maternal Age-Specific Rates for Trisomy 21 and Common Autosomal Trisomies in Fetuses from a Single Diagnostic Center in Thailand

To provide maternal age-specific rates for trisomy 21 (T21) and common autosomal trisomies (including trisomies 21, 18 and 13) in fetuses. We retrospectively reviewed prenatal cytogenetic results obtained between 1990 and 2009 in Songklanagarind Hospital, a university teaching hospital, in southern Thailand. Maternal age-specific rates of T21 and common autosomal trisomies were established using different regression models, from which only the fittest models were used for the study. A total of 17,819 records were included in the statistical analysis. The fittest models for predicting rates of T21 and common autosomal trisomies were regression models with 2 parameters (Age and Age²). The rate of T21 ranged between 2.67 per 1,000 fetuses at the age of 34 and 71.06 per 1,000 at the age of 48. The rate of common autosomal trisomies ranged between 4.54 per 1,000 and 99.65 per 1,000 at the same ages. This report provides the first maternal age-specific rates for T21 and common autosomal trisomies fetuses in a Southeast Asian population and the largest case number of fetuses have ever been reported in Asians.

Increased prevalence of major congenital anomalies in births with placental abruption

OBJECTIVE

To examine the association between major congenital anomalies and placental abruption.

METHODS

A register-based retrospective case-control study was carried out from 1987 to 2005. Data on baseline characteristics and birth outcomes were collected from three Finnish national health registers: the Medical Birth Register, National Hospital Discharge Register, and Register of Congenital Malformations. The study population consisted of 4,190 women with singleton birth and placental abruption. Three control women without placental abruption were selected for each case, matched by maternal age, parity, year of birth, and hospital district. The main outcome measure of the study was a major congenital anomaly associated with placental abruption.

RESULTS

In total, 261 (prevalence 623/10,000) births with placental abruption and 415 (prevalence 330/10,000) control births had major congenital anomalies (odds ratio [OR] 1.92, 95% confidence interval [CI] 1.6-2.52). The association was strongest among births with growth restriction and prematurity. Adjusted analysis revealed a significant association with central nervous system anomalies (OR 2.33, 95% CI 1.29-4.23), anomalies of the eyes and ears (OR 1.82, 95% CI 1.08-3.09), cardiovascular anomalies (OR 1.78, 95% CI 1.34-2.37), respiratory anomalies (OR 3.51, 95% CI 1.56-7.90), gastrointestinal anomalies (OR 3.81, 95% CI 2.27-6.41), genitourinary anomalies (OR 2.55, 95% CI 1.73- 3.74), musculoskeletal anomalies (OR 1.67, 95% CI 1.24-2.24), and anomalies of integument (OR 3.29, 95% CI 1.20-8.98) in births complicated by placental abruption.

CONCLUSIONS

Major congenital anomalies are twice as common among neonates born from pregnancies complicated by placental abruption compared with control pregnancies without abruption. This observation applies to several organ systems.

LEVEL OF EVIDENCE

II.

High prevalence of sacrococcygeal teratoma in Finland - a nationwide population-based study

AIM

The birth prevalence of sacrococcygeal teratoma (SCT) has been reported to range from 1:27 000 to 1:40 000. We assessed the population-based prevalence and clinical presentation of SCT over 22 years.

METHODS

We identified all cases of SCT, including live births, stillbirths and terminations of pregnancy (TOPs), in the Finnish Register of Congenital Malformations, covering 1987-2008. Data on prenatal diagnoses, pregnancy outcomes, infant deaths and associated anomalies were collected.

RESULTS

One hundred and twenty four SCT cases were identified among 1 331 699 pregnancies. There were 89 (72%) live births, 13 (10%) stillbirths and 22 (18%) TOPs. The total prevalence of SCT was 1:10 700. Tumours were detected in utero in 55% of the pregnancies with SCT. The proportion of perinatal deaths among all SCT births was 28%. Thirty percentage of the cases had associated abnormalities (mainly of the urinary tract and various syndromes).

CONCLUSION

This nationwide, population-based study on SCT shows that the total and birth prevalence of SCT in Finland is markedly higher than previously reported. This may reflect true differences between populations, but may also be explained by accurate nationwide registration of SCTs. The high perinatal mortality rate has an impact on counselling of families and planning of deliveries.

Changes in mortality and causes of death in the Swedish Down syndrome population

During the past few decades age at death for individuals with Down syndrome (DS) has increased dramatically. The birth frequency of infants with DS has long been constant in Sweden. Thus, the prevalence of DS in the population is increasing. The aim of the present study was to analyze mortality and causes of death in individuals with DS during the period 1969-2003. All individuals with DS that died between 1969 and 2003 in Sweden, and all individuals born with DS in Sweden between 1974 and 2003 were included. Data were obtained from the Swedish Medical Birth Register, the Swedish Birth Defects Register, and the National Cause of Death Register. Median age at death has increased by 1.8 years per year. The main cause of death was pneumonia. Death from congenital heart defects decreased. Death from atherosclerosis was rare but more frequent than reported previously. Dementia was not reported in any subjects with DS before 40 years of age, but was a main or contributing cause of death in 30% of the older subjects. Except for childhood leukemia, cancer as a cause of death was rare in all age groups. Mortality in DS, particularly infant mortality, has decreased markedly during the past decades. Median age at death is increasing and is now almost 60 years. Death from cancer is rare in DS, but death from dementia is common.

Characteristics and associated anomalies in radial ray deficiencies in Finland--a population-based study

Upper-limb defects with deficiencies of the radial ray have varying etiologies, with a low proportion of true Mendelian disorders. We carried out a population-based study to elucidate the birth prevalence and clinical spectrum of radial ray deficiencies in Finland. We identified all births with radial ray deficiency reported to the Finnish Register of Congenital Malformations in 1993-2005. Altogether 138 cases were identified (123 live births), with a birth prevalence of 1.83 per 10,000 births and a live birth prevalence of 1.64 per 10,000 live births. The proportion of infant deaths was as high as 35%. The majority of the cases were associated with known syndromes or multiple anomalies; only 13% were true isolated radial ray deficiencies. The most common syndrome was trisomy 18, and the most common in multiple anomalies was VACTERL association. In 8.7% of cases an association between radial ray deficiency and heart anomaly was observed. The high proportion of cases with associated major anomalies indicates that radial ray deficiency can be regarded isolated only after thorough assessment of the various organ systems in an affected infant.

Trends in survival among children with Down syndrome in 10 regions of the United States

OBJECTIVE

This study examined changes in survival among children with Down syndrome (DS) by race/ethnicity in 10 regions of the United States. A retrospective cohort study was conducted on 16,506 infants with DS delivered during 1983-2003 and identified by 10 US birth defects monitoring programs. Kaplan-Meier survival probabilities were estimated by select demographic and clinical characteristics. Adjusted hazard ratios (aHR) were estimated for maternal and infant characteristics by using Cox proportional hazard models.

RESULTS

The overall 1-month and 1-, 5-, and 20-year survival probabilities were 98%, 93%, 91%, and 88%, respectively. Over the study period, neonatal survival did not improve appreciably, but survival at all other ages improved modestly. Infants of very low birth weight had 24 times the risk of dying in the neonatal period compared with infants of normal birth weight (aHR 23.8; 95% confidence interval [CI] 18.4-30.7). Presence of a heart defect increased the risk of death in the postneonatal period nearly fivefold (aHR 4.6; 95% CI 3.9-5.4) and continued to be one of the most significant predictors of mortality through to age 20. The postneonatal aHR among non-Hispanic blacks was 1.4 (95% CI 1.2-1.8) compared with non-Hispanic whites and remained elevated by age 10 (2.0; 95% CI 1.0-4.0).

CONCLUSIONS

The survival of children born with DS has improved and racial disparities in infant survival have narrowed. However, compared with non-Hispanic white children, non-Hispanic black children have lower survival beyond infancy. Congenital heart defects are a significant risk factor for mortality through age twenty.

Infant and childhood neurodevelopmental outcomes following prenatal exposure to selective serotonin reuptake inhibitors: overview and design of a Finnish Register-Based Study (FinESSI)

BACKGROUND

Experimental animal studies and one population-based study have suggested an increased risk for adverse neurodevelopmental outcome after prenatal exposure to SSRIs. We describe the methods and design of a population-based study examining the association between prenatal SSRI exposure and neurodevelopment until age 14.

METHODS AND DESIGN

This is a cohort study of national registers in Finland: the Medical Birth Register, the Register of Congenital Malformations, the Hospital Discharge Register including inpatient and outpatient data, the Drug Reimbursement Register, and the Population Register. The total study population includes 845,345 women and their live-born, singleton offspring aged 14 or younger and born during Jan 1st 1996-Dec 31st 2010. We will compare the prevalence of psychiatric and neurodevelopmental outcomes in offspring exposed prenatally to SSRIs to offspring exposed to prenatal depression and unexposed to SSRIs. Associations between exposure and outcome are assessed by statistical methods including specific modeling to account for correlated outcomes within families and differences in duration of follow-up between the exposure groups. Descriptive results. Of all pregnant women with pregnancy ending in delivery (n=859,359), 1.9% used SSRIs. The prevalence of diagnosed depression and depression-related psychiatric disorders within one year before or during pregnancy was 1.7%. The cumulative incidence of registered psychiatric or neurodevelopmental disorders was 6.9% in 2010 among all offspring born during the study period (age range 0-14 years).

DISCUSSION

The study has the potential for significant public health importance in providing information on prenatal exposure to SSRIs and long-term neurodevelopment.

Prevalence of esophageal atresia among 18 international birth defects surveillance programs

BACKGROUND

The prevalence of esophageal atresia (EA) has been shown to vary across different geographical settings. Investigation of geographical differences may provide an insight into the underlying etiology of EA.

METHODS

The study population comprised infants diagnosed with EA during 1998 to 2007 from 18 of the 46 birth defects surveillance programs, members of the International Clearinghouse for Birth Defects Surveillance and Research. Total prevalence per 10,000 births for EA was defined as the total number of cases in live births, stillbirths, and elective termination of pregnancy for fetal anomaly (ETOPFA) divided by the total number of all births in the population.

RESULTS

Among the participating programs, a total of 2943 cases of EA were diagnosed with an average prevalence of 2.44 (95% confidence interval [CI], 2.35-2.53) per 10,000 births, ranging between 1.77 and 3.68 per 10,000 births. Of all infants diagnosed with EA, 2761 (93.8%) were live births, 82 (2.8%) stillbirths, 89 (3.0%) ETOPFA, and 11 (0.4%) had unknown outcomes. The majority of cases (2020, 68.6%), had a reported EA with fistula, 749 (25.5%) were without fistula, and 174 (5.9%) were registered with an unspecified code.

CONCLUSIONS

On average, EA affected 1 in 4099 births (95% CI, 1 in 3954-4251 births) with prevalence varying across different geographical settings, but relatively consistent over time and comparable between surveillance programs. Findings suggest that differences in the prevalence observed among programs are likely to be attributable to variability in population ethnic compositions or issues in reporting or registration procedures of EA, rather than a real risk occurrence difference. Birth Defects Research (Part A), 2012.

Digitization of clinical and epidemiological data from the Kyoto Collection of Human Embryos: maternal risk factors and embryonic malformations

Understanding the causes of congenital anomalies is of prime importance to develop management and/or prevention strategies. It is widely accepted that the occurrence of congenital malformations in fetuses and neonates is heavily correlated with maternal genetic makeup and lifestyle. However, very few epidemiologic analyses have been conducted on the embryonic developmental period because of the rarity of data available. Instigated in 1961, the Kyoto Collection of Human Embryos comprises approximately 45,000 specimens of embryos and fetuses. The collection's most unique feature is that most specimens were added to the collection along with epidemiologic information on the respective mothers. This is the first report on the digitization of data from the collection. A total of 22,262 embryonic specimens were selected on the basis of data integrity. Data related to the embryos were then classified according to the following criteria: developmental stage, sampling period, geographical area, maternal determinant, and external malformation. Results indicate that 7.8% of the embryos exhibit external anomalies and 92.2% are without anomalies. The three most common anomalies were nuchal bleb, holoprosencephaly and spina bifida. A special emphasis was placed on the potential association between maternal determinants and embryonic external anomalies, allowing for statistical analyses. The present study provides further evidence that this collection represents a unique source of information to conduct epidemiological analyses, not only to further the understanding of congenital anomalies but also to help establish preventive health guidelines for pregnant women.

Predictors of trisomy 21 in the offspring of older and younger women

BACKGROUND

Advanced maternal age is the only well-established risk factor for trisomy 21, yet the majority of affected individuals are born to younger women. To identify factors associated with the risk of trisomy 21 in the offspring of younger and older women, we analyzed data for cases with trisomy 21 from the Texas Birth Defects Registry for 1999 to 2007.

METHODS

Data were analyzed separately for younger (i.e., <35 years of age at delivery; n = 2306) and older (i.e., ≥ 35 years of age at delivery; n = 1811) women using Poisson regression.

RESULTS

After adjustment for maternal age and several other covariates, the prevalence of trisomy 21 in the offspring of women in both maternal age groups was higher in male than in female infants and in offspring of women who were Hispanic (compared with non-Hispanic white women) or who had at least one previous liveborn child compared to those with none. In the offspring of older women only, the prevalence of trisomy 21 was also significantly higher when the father was 20 to 24 years old (compared with 25 to 29 years old; adjusted prevalence ratio [aPR], 2.27; 95% confidence interval [CI], 1.47-3.49) and Hispanic (compared with non-Hispanic white; aPR, 1.34; 95% CI, 1.13-1.58) and among women with less than a high school education (compared with greater than high school).

CONCLUSIONS

This study identified several factors, in addition to maternal age, that were associated with trisomy 21 risk. In general, these factors were similar for both maternal age groups, although paternal characteristics were significantly associated with risk of trisomy 21 only in offspring of older women.

Abnormal microRNA expression in Ts65Dn hippocampus and whole blood: contributions to Down syndrome phenotypes

Down syndrome (DS; trisomy 21) is one of the most common genetic causes of intellectual disability, which is attributed to triplication of genes located on chromosome 21. Elevated levels of several microRNAs (miRNAs) located on chromosome 21 have been reported in human DS heart and brain tissues. The Ts65Dn mouse model is the most investigated DS model with a triplicated segment of mouse chromosome 16 harboring genes orthologous to those on human chromosome 21. Using ABI TaqMan miRNA arrays, we found a set of miRNAs that were significantly up- or downregulated in the Ts65Dn hippocampus compared to euploid controls. Furthermore, miR-155 and miR-802 showed significant overexpression in the Ts65Dn hippocampus, thereby confirming results of previous studies. Interestingly, miR-155 and miR-802 were also overexpressed in the Ts65Dn whole blood but not in lung tissue. We also found overexpression of the miR-155 precursors, pri- and pre-miR-155 derived from the miR-155 host gene, known as B cell integration cluster, suggesting enhanced biogenesis of miR-155. Bioinformatic analysis revealed that neurodevelopment, differentiation of neuroglia, apoptosis, cell cycle, and signaling pathways including ERK/MAPK, protein kinase C, phosphatidylinositol 3-kinase, m-TOR and calcium signaling are likely targets of these miRNAs. We selected some of these potential gene targets and found downregulation of mRNA encoding Ship1, Mecp2 and Ezh2 in Ts65Dn hippocampus. Interestingly, the miR-155 target gene Ship1 (inositol phosphatase) was also downregulated in Ts65Dn whole blood but not in lung tissue. Our findings provide insights into miRNA-mediated gene regulation in Ts65Dn mice and their potential contribution to impaired hippocampal synaptic plasticity and neurogenesis, as well as hemopoietic abnormalities observed in DS.

Nationwide register-based surveillance system on drugs and pregnancy in Finland 1996-2006

PURPOSE

The aim of this population-based nationwide drugs and pregnancy surveillance system was to get basic information on the use of prescribed drugs during pregnancy and to achieve more detailed information on drug exposure-outcome associations with data obtained from the Finnish national health registers.

METHODS

The data are based on information on all pregnancies ending in births (n = 632,629) or termination of pregnancy (TOP) (n = 117,255) in Finland between 1996 and 2006. The data containing information on maternal background factors, chronic diseases and drug purchases during pregnancy, born children, induced abortions, perinatal health and major congenital malformations were obtained from the Finnish national health registers. Information from the different registers was merged through record linkages based on unique personal identification numbers. Statistical analyses were conducted between the exposed and unexposed for individual drugs or Anatomical Therapeutic Chemical (ATC) classification drug groups in multivariate logistic regression including potential confounding factors.

RESULTS

Nearly half of parturients and almost every third woman with TOP purchased drugs at least once 1 month prior to pregnancy and/or during pregnancy. The most frequent chronic diseases during pregnancy were asthma, hypothyroidism, epilepsy, rheumatoid arthritis and diabetes. Previously known causal connections between maternal chronic diseases and/or medication and perinatal health risks were already seen in the ATC-group-level analysis.

CONCLUSIONS

Comprehensive and detailed information for pharmacoepidemiological research on the effects of drug use during pregnancy in a cohort setting is possible with long-term and cumulative data collection.