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Gradual implementation of first trimester screening in a population with a prior screening strategy: population based
Pavel Calda1, Antonín Sípek, Vladimír Gregor
1Department of Obstetrics and Gynecology of the First Faculty of Medicine and General University Hospital, First Faculty of Medicine, Charles University in Prague, Prague, Czech Republic. calda@gynstart.cz
Insights
First trimester screening in the Czech Republic reduced newborn Down's syndrome cases despite rising maternal age. This screening improved early diagnosis rates for chromosomal abnormalities.
Area of Science:
- Prenatal diagnostics and genetic screening
- Reproductive health and obstetrics
- Public health policy and implementation
Background:
- The Czech Republic implemented first trimester screening between 1996 and 2007.
- This period saw an increase in maternal age, a known risk factor for chromosomal anomalies.
- Understanding the impact of screening on diagnostic rates and invasive procedures is crucial.
Purpose of the Study:
- To evaluate the effectiveness of first trimester screening implementation in the Czech Republic.
- To assess changes in the incidence of numerical chromosomal anomalies, particularly Down's syndrome.
- To analyze gestational age at diagnosis and the rates of invasive diagnostic procedures like CVS and amniocentesis.
Main Methods:
- A population-based cohort study was conducted.
- Data were sourced from the National Registry of Congenital Anomalies and 53 genetic departments.
- Approximately 100,000 pregnancies per year were analyzed over the study period.
Main Results:
- Newborns with Down's syndrome decreased from 5.42 to 3.66 per 10,000 births between 1996 and 2007.
- Detection rates for Down's syndrome increased in both younger (<35 years) and older (>35 years) maternal age groups.
- The number of amniocenteses per detected Down's syndrome case remained stable, while chorionic villus sampling (CVS) decreased significantly.
Conclusions:
- First trimester screening successfully reduced the number of newborns with Down's syndrome, even with increasing maternal age.
- The implementation led to earlier diagnoses of major chromosomal abnormalities.
- Screening strategies effectively shifted diagnostic procedures towards earlier detection.
Objective:
To evaluate the implementation of first trimester screening in the Czech Republic during 1996-2007 on the number of infants born with numerical chromosomal anomalies, the gestational age at diagnosis and the number of invasive procedures.
Design:
A population based cohort study.
Setting:
National Registry of Congenital Anomalies, 53 Czech Republic Genetic Departments.
Population:
About 100,000 pregnancies per year.
Main Outcome Measures:
Primary outcomes were the rates of fetuses and newborns with diagnosed numerical chromosomal anomalies and the gestational age at diagnosis. Secondary outcomes were the rates of chorion villus sampling (CVS) and amniocenteses and the contribution of age groups on the detection rate of trisomy 21.
Results:
The number of newborns with Down's syndrome decreased from 5.42/10,000 in 1996 to 3.66/10,000 newborns in the 2007. The total incidence of Down's syndrome increased from 13.42 to 20.66/10,000. The detection rate in women <35 years increased from 35.59 in 1996 to 45.08 in 2007; in women >35 years from 23.73 to 38.52. The number of amniocenteses/detected case of Down's syndrome was 124 in 1996 and 123 in 2007. The corresponding number of CVS decreased dramatically from 83 in 1996 to 10 in 2007.
Conclusions:
Despite the increase of maternal age and the corresponding increase of Down's syndrome, the number of newborns with Down's syndrome decreased. Implementation of the first trimester combined screening leads to a shift towards earlier diagnosis of all major chromosomal abnormalities.
