One of the goals of the registration is to monitor the prevalence of congenital anomalies over time. In the graphs presented below, the prevalence rates per year are shown for a period of ten years. We present the graphs from 2015 onwards. The prevalence of total births is shown, except for those anomalies where a major impact of prenatal diagnosis and selective termination of pregnancy can be expected. In those cases, total births and terminated pregnancies are presented. The Y-axis represents the observed prevalence of the selected congenital anomaly per 10,000 births, with adjustment of scale according to the magnitude of the counts. Confidence intervals are not presented, since our registry is covering a complete population and not a sample of the population.
First, all congenital anomalies together were analysed. Subsequently, we analysed genetic disorders and Down syndrome. Finally, we studied specific malformations excluding genetic disorders. This resulted in a group of so-called ‘non genetic’ anomalies, where environmental factors could play a role.
In addition to graphical presentation of prevalences, chi-square testing for independence and linear trend was performed, using the basic statistics functions of RStudio. The results of chi-square testing for independence and trend are presented under each figure and the period tested is 2015-2023. The last year, in this case 2024, is not included in the statistical testing due to incomplete data collection.
The total prevalence for all congenital anomalies as a group is fluctuating over time, ranging from 344.7 per 10,000 births in 2015 to 305.0 per 10,000 births in 2023. The decline in numbers in the most recent years is likely caused by incomplete registration of all cases for these years.
Prevalence per 10,000 births by birth year, n = 5062
The prevalence of the group of genetic disorders shows no trend over time (2015-2023).
Prevalence per 10,000 births by birth year, n= 1350
Down syndrome (trisomy 21) is the most prevalent chromosomal anomaly. The prevalence is stable over time.
Prevalence and 95% Cl per 10,000 births per birth year, n = 356
The prevalence of neural tube defects (anencephaly, spina bifida and encephalocele) fluctuates from 2015 to 2023 and might seem to decrease in time, but no statistically significant trend is observed.
Prevalence per 10,000 births by birth year, n = 142
Heart anomalies are among the most common congenital anomalies. The prevalence of all congenital heart anomalies combined, not associated with a genetic or syndromal condition, is relatively stable over the time period 2015-2023. There is no trend over time.
Prevalence per 10,000 births by birth year, n = 1034
Ventricular septum defects (VSD) are one of the most common heart defects. The prevalence is relatively stable over time.
Prevalence per 10,000 births by birth year, n = 515
From 2015 to 2023, oro-facial clefts have a prevalence varying between 11.7 and 22.9 per 10.000 births. The prevalence fluctuates, but there is no trend over time.
Prevalence per 10,000 births by birth year, n = 244
The prevalence of cleft lip with or without palate is relatively stable over time and shows no trend.
Prevalence per 10,000 births by birth year, n = 163
The prevalence of hypospadias is stable over time. No decreasing or increasing trend is found.
Prevalence per 10,000 births by birth year, n = 458
The prevalence of urinary tract anomalies is relatively stable from 2015 to 2023. Although the prevalence might seem to decrease slightly over time, no statistically significant trend is found.
Prevalence per 10,000 births by birth year, n= 776
The prevalence of hydronephrosis shows some decrease over time, but no statistically significant trend is found.
Prevalence per 10,000 births by birth year, n = 318
The prevalence of limb anomalies is relatively stable from 2015 to 2023. Although the prevalence might seem to decrease slightly over time, no statistically significant trend is found.
Prevalence per 10,000 births by birth year, n = 742
