The incidence of gastroschisis

Editor—Kilby says that gastroschisis shows an increasing temporal trend in the number of affected babies born in the United Kingdom,¹ a trend that has also been observed in other parts of the world.²

We evaluated the data of 25 registries of members of the International Clearinghouse for Birth Defects Surveillance and Research (ICBDSR) with more than seven yearsofdata—a homogeneously ascertained and reliable dataset on termination of pregnancies.³ Fourteen registries showed a significant increasing temporal trend of gastroschisis (table). No similar trend was observed in the 36 malformations analysed in the dataset. We excluded the possible bias of a simultaneous decreasing trend in omphalocele indicating changes in reporting nomenclature or coding.

Table 1.

Rates of gastroschisis in 14 members' registries of International Clearinghouse for Birth Defects Surveillance and Research with significant temporal trend

	Rate per 10 000		P trend (χ2 test)
Registry	First three years	Last three years
Japan (1974-2003)	0.96	2.58	<0.01
Australia:
Western Australia (1980-2003)	1.53	4.30	<0.01
Victoria (1983-2003)	0.71	2.44	<0.01
Canada Alberta (1980-2003)	1.57	3.53	<0.01
USA Atlanta (1974-2003)	0.85	2.48	<0.05
Mexico (RYVEMCE) (1980-2003)	1.44	5.11	<0.01
South America (ECLAMC) (1974-2003)	0.04	2.92	<0.01
Norway (1974-2003)	1.34	2.74	<0.01
Finland (1993-2003)	1.70	3.73	<0.01
Ireland Dublin (1980-2003)	0.13	2.05	<0.01
England and Wales (1995-2003)	1.52	2.05	<0.01
France:
Paris (1981-2003)	0.18	3.44	<0.01
Central East (1978-2003)	0.42	1.60	<0.01
Slovak Republic (1995-2003)	0.55	1.10	<0.05

RYVEMCE=Mexican Registry and Epidemiological Surveillance of External Congenital Malformations. ECLAMC=Estudio Colaborativo Latino Americano de Malformaciones Congénitas.

The 11 registries with non-significant temporal trend (mean rate per 10 000 of the period): USA Texas 1996-2002 (3.85); Netherlands North 1981-2003 (0.81); Germany Saxony Anhalt 1987-2003 (1.54); Hungary 1982-2003 (0.38); Italy North-East 1981-2003 (0.51); Italy Emilia Romagna 1978-2003 (0.81); Italy Tuscany 1992-2003 (0.42), Italy Campania 1991-2003 (0.58); Malta 1993-2003 (1.02); Israel Birth Defects Monitoring System 1978-2003 (0.29); United Arab Emirates 1996-2003 (0.79).

The increasing trend of gastroschisis is worldwide—namely, Japan, Australia, North-Central-South America, North-Central Europe—but not universal. For example, in Italy four regional birth defects registries (all with a rate between 0.4 and 0.8 per 10 000) have not seen any increase in the past 25 years.

Any explanation of this worldwide epidemic should consider the rate variation around the world, the increasing rate experienced worldwide but not universally, and the consistent increased risk in young mothers found in all studies performed. Aetiological research should be concentrated on large enough material, such as only an international collaboration can provide. Unfortunately, almost all birth defects registries are experiencing a chronic lack of funds, and no such study can be planned.