International trends of Down syndrome 1993-2004: Births in relation to maternal age and terminations of pregnancies.
BACKGROUND
The aim of this study was to examine trends of Down syndrome (DS) in relation to maternal age and termination of pregnancies (ToP) in 20 registries of the International Clearinghouse for Birth Defects Surveillance and Research (ICBDSR).


METHODS
Trends of births with DS (live-born and stillborn), ToP with DS, and maternal age (percentage of mothers older than 35 years) were examined by year over a 12-year period (1993-2004). The total mean number of births covered was 1550,000 annually.


RESULTS
The mean percentage of mothers older than 35 years of age increased from 10.9% in 1993 to 18.8% in 2004. However, a variation among the different registers from 4-8% to 20-25% of mothers >35 years of age was found. The total mean prevalence of DS (still births, live births, and ToP) increased from 13.1 to 18.2/10,000 births between 1993 and 2004. The total mean prevalence of DS births remained stable at 8.3/10,000 births, balanced by a great increase of ToP. In the registers from France, Italy, and the Czech Republic, a decrease of DS births and a great increase of ToP was observed. The number of DS births remained high or even increased in Canada Alberta, and Norway during the study period.


CONCLUSIONS
Although an increase in older mothers was observed in most registers, the prevalence of DS births remained stable in most registers as a result of increasing use of prenatal diagnostic procedures and ToP with DS.
Cocchi
Guido
G
Istituto Clinico di Pediatria Preventiva e Neonatologia, Bologna, Italy.
Gualdi
Silvia
S
Bower
Caroline
C
Halliday
Jane
J
Jonsson
Björn
B
Myrelid
Asa
A
Mastroiacovo
Pierpaolo
P
Amar
Emmanuelle
E
Bakker
Marian K
MK
Correa
Andrea
A
Doray
Berenice
B
Melve
Kari Klungsør
KK
Koshnood
Babak
B
Landau
Daniella
D
Mutchinick
Osvaldo M
OM
Pierini
Anna
A
Ritvanen
Anukka
A
Ruddock
Vera
V
Scarano
Giocchino
G
Sibbald
Barbara
B
Sípek
Antonin
A
Tenconi
Romano
R
Tucker
Dave
D
Annerén
Göran
G
D000028:Abortion, Induced; D004314:Down Syndrome / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008423:Maternal Age; D011247:Pregnancy; D015995:Prevalence