EUROCAT Northern Netherlands

Update: March 2022

One of the goals of the Eurocat NNL 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 2011 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 prevalence, 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 2011-2019. The last year, in this case 2020, is not included in the statistical testing due to ongoing data collection.

1. All congenital anomalies

There is gradual (significant) decrease in overall prevalence of all congenital anomalies together as a group. Data collection is an ongoing process and the decline in numbers in the most recent years is largely caused by the fact that registration is still not complete for these years. It also fluctuates over the time period 2011-2019.

All congenital anomalies
prevalence and 95%CI per 10,000 births, per birth year (N=5337)

2. Chromosomal anomalies

The prevalence of the group of Chromosomal anomalies does not show a significant difference over time.

Chromosomal anomalies
prevalence and 95% CI per 10,000 births, per birth year (N=769)

2a. Down syndrome

Down syndrome (trisomy 21) is the most prevalent chromosomal anomaly. There is no statistically significant difference in time. The proportion of terminated pregnancies in this period shows a heterogeneous pattern but not statistically significant.

Down syndrome (trisomy 21)
prevalence and 95% CI per 10,000 births, per birth year (N=333)

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=138)

4. Ear and eye anomalies

Eye and ear anomalies show a decreasing trend in the period 2011-2019. This might be due to an incomplete registration over the last years. Also be aware that the total number is very low, n=76.

Ear and eye anomalies (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=76)

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 syndromic condition, is relatively stable over the time period 2011-2019. There is also no trend over time.

Heart anomalies (non-genetic)
prevalence and 95% CI per 10,000 births, per birth year (N=1031)

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=536)

6. Oro-facial clefts

Clefts are relatively common group of anomalies with a prevalence varying between 12 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=236)

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=168)

6b. Cleft palate

The prevalence of cleft  palate shows a heterogeneous pattern over time but without a significant time trend. The prevalence is varying from 11 to 19.8 per 10.000 births.

Cleft palate (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=74)

7. Genital anomalies

The prevalence of genital anomalies is relatively stable over time and shows no trend in time.

Genital anomalies (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=419)

7a. Hypospadia

The prevalence of hypospadia is stable over time.

Hypospadia (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=396)

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=705)

8a. Hydronephrosis

The prevalence of hydronephrosis shows a significant heterogeneous pattern over time with prevalence ranging from 21 to 29.7 per 10.000 births. There was no significant in- or decreasing trend over time.

Hydronephrosis (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=310)

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 2014 we followed the international coding rule of Eurocat to not register congenital hip dysplasia anymore. This anomaly concerned large numbers so the significant decrease is obvious and explained.

Limb anomalies (non-genetic)
total prevalence and 95% CI per 10,000 births, per birth year (N=999)

9a. Limbs reduction defects

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=75)

10. Multiple congenital anomalies

The prevalence of the group of cases with multiple congenital anomalies shows a relatively stable pattern in the period 2011-2019. This applies to both the total prevalence and the proportion of terminated pregnancies.

Multiple congenital anomalies  
prevalence and 95% CI per 10,000 births, per birth year (N=248)