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 2013 onwards. The prevalence of total births are shown, (with 95% confidence interval) 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.
First, all congenital anomalies together were analysed. Subsequently, we analysed chromosomal anomalies 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 and 95% confidence intervals (CI) was performed. The results of chi-square testing for independence and trend are presented under each figure and the period tested is 2013-2021. The last year, in this case 2022, is not included in the statistical testing due to incomplete data collection.
The total prevalence for all congenital anomalies as a group decreases significantly over time from 390.1 per 10,000 births in 2013 to 292.8 per 10,000 births in 2021. The decline in numbers in the most recent years is largely caused by incomplete registration of all cases for these years.
Prevalence and 95%CI per 10,000 births, per birth year (N=5251)
The prevalence of the group of chromosomal anomalies shows an increasing trend over time (2013-2022).
Prevalence and 95%CI per 10,000 births, per birth year (N=683)
Down syndrome (trisomy 21) is the most prevalent chromosomal anomaly. There is a slightly increasing trend in the total prevalence of Down syndrome, which was statistically significant.
Prevalence and 95%CI per 10,000 births, per birth year (N=337)
The prevalence of neural tube defects (anencephaly, spina bifida and encephalocele) seems to fluctuate over the years, but not in a statistically significant way.
Prevalence and 95%CI per 10,000 births, per birth year (N=141)
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 2013-2022. There is also no trend over time.
Prevalence and 95%CI per 10,000 births, per birth year (N=1058)
Ventricular septum defects (VSD) are one of the most common heart defects. The prevalence is relatively stable over time.
Prevalence and 95%CI per 10,000 births, per birth year (N=532)
Oro-facial clefts have a prevalence varying between 11.2 and 20.9 per 10.000 births. The prevalence is fluctuating and there is no increasing or decreasing trend over time.
Prevalence and 95%CI per 10,000 births, per birth year (N=244)
The prevalence of cleft lip with or without palate is relatively stable over time and shows no trend in time.
Prevalence and 95%CI per 10,000 births, per birth year (N=161)
The prevalence of hypospadias is stable over time. No decreasing or increasing trend is found.
Prevalence and 95%CI per 10,000 births, per birth year (N=428)
The prevalence of urinary tract anomalies is slightly decreasing over time, which showed a statistically significant linear trend.
Prevalence and 95%CI per 10,000 births, per birth year (N=797)
Hydronephrosis shows a decreasing prevalence over time, which was also statistically significant.
Prevalence and 95%CI per 10,000 births, per birth year (N=364)
The prevalence of limb anomalies is decreasing over time and shows a statistically downwards trend. It is clear from the graph there is a dip in the prevalence after 2014. Since this moment it was decided, following an international coding rule, that we do not register congenital hip dysplasia anymore. Since this anomaly concerned large numbers the significant decrease is obvious and explained. After excluding birth year 2013 from the linear trend analysis, the decreasing trend was less strong, but remained statistically significant (X2 for trend = 7.63, p = 0.01).
Prevalence and 95%CI per 10,000 births, per birth year (N=891)
