EUROCAT Northern Netherlands

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 2012 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, the groups of all congenital anomalies together were analyzed. Subsequently, we analyzed chromosomal anomalies. Finally, we studied specific malformations excluding chromosomal and monogenic disorders and deletions. 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 trend and 95% confidence intervals was performed. The results chi-square testing for independence and trend are presented under each figure and the period tested is 2012-2020. The last year, in this case 2021, is not included in the statistical testing due to lack of completeness.

1. All congenital anomalies

The total prevalence for all congenital anomalies as a group fluctuates over time from 382.8 per 10,000 births in 2012 to 340.7 per 10,000 births in 2020. The decline in numbers in the most recent years is largely caused by incomplete registration of all cases for these years.

All congenital anomalies
prevalence and 95%CI per 10,000 births, per birth year (N=5338)

2. Chromosomal anomalies

The prevalence of the group of chromosomal anomalies shows a significant increasing trend over time (2012-2020).

Chromosomal anomalies
prevalence and 95% CI per 10,000 births, per birth year (N=772)

2a. Down syndrome

Down syndrome (trisomy 21) is the most prevalent chromosomal anomaly. There is an increasing trend in total prevalence for Down syndrome and in termination of pregnancies for Down syndrome.

Down syndrome (trisomy 21)
prevalence and 95% CI per 10,000 births, per birth year (N=337)

3. Neural tube Defects

The prevalence of neural tube defects (anencephaly, spina bifida and encephalocele) seems to fluctuate over the last nine years, but not in a statistically significant way.

Neural tube defects (non-genetic)
prevalence and 95% CI per 10,000 births, per birth year (N=136)

4. Ear and eye anomalies

Eye and ear anomalies show no trend in the period 2012-2020.

Ear and eye anomalies (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=86)

5. Heart anomalies

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 2012-2020. There is also no trend over time.

Heart anomalies (non-genetic)
prevalence and 95% CI per 10,000 births, per birth year (N=1045)

5a. VSD

Ventricular septum defects (VSD) are one of the most common heart defects. The prevalence is relatively stable over time.

VSD (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=525)

6. Oro-facial clefts

Clefts are relatively common group of anomalies with a prevalence varying between 12.6 and 19.8 per 10.000 births. The prevalence is relatively stable over time.

Oro-facial clefts (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=239)

6a. Cleft lip with or without palate

The prevalence of cleft lip with or without palate is relatively stable over time and shows no trend in time.

Cleft lip with or without cleft palate (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=161)

6b. Cleft palate

The prevalence of cleft palate (without cleft lip) is relatively stable over time and shows no trend in time.

Cleft palate (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=81)

7. Hypospadias

The prevalence of hypospadias is stable over time.

Hypospadias (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=394)

8. Urinary anomalies

The prevalence of urinary anomalies is stable over time.

Urinary anomalies (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=692)

8a. Hydronephrosis

The prevalence of hydronephrosis is stable over time.

Hydronephrosis (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=319)

9. Limb anomalies

The prevalence of limb anomalies is statistically heterogeneous over time and shows a decreasing trend. It is clear from the graph there is a dip in the prevalence after 2014. Since this 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.

Limb anomalies (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=958)

9a. Reduction defects limbs

The prevalence of reduction defects of the limbs is stable over time.

Reduction defects Limbs (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=82)

10. Multiple congenital anomalies

The prevalence of the group cases with of Multiple Congenital Anomalies shows a relatively stable pattern in the period 2012-2020. This is true for the total prevalence as well as for the proportion of terminated pregnancies.

Multiple congenital anomalies  
prevalence and 95% CI per 10,000 births, per birth year (N=238)