Editor—Kilby drew attention to the increasing incidence of gastroschisis in the United Kingdom, particularly among babies of young mothers.1 This has also been shown by Donaldson and by Mastroiacovo et al (previous letter).2
In the Spanish collaborative study of congenital malformations (ECEMC), an ongoing case-control study and surveillance system,3-5 we have also observed an apparent increasing trend in the birth prevalence of gastroschisis in Spain among mothers younger than 20 but not among older mothers (table).
Table 1.
Birth prevalence of gastroschisis per 10 000 newborn infants (with 95% confidence intervals) in two age groups in Spain between 1980 and 2004
| Maternal age | 1980-5 | 1986-99 | 2000-4 |
|---|---|---|---|
| <20* | 1.57 (0.43 to 4.02) | 2.24 (1.16 to 3.91) | 2.99 (0.97 to 6.98) |
| ≥20† | 0.48 (0.28 to 0.76) | 0.30 (0.20 to 0.42) | 0.27 (0.15 to 0.46) |
Total population surveyed=95 814.
Total population surveyed=1 949 593.
Our results do not reach significance, although the sample sizes are small, so we cannot rule out that the observed increase was by chance. However, termination of pregnancy after detecting fetal anomalies has been legal in Spain since 1985, and data on such terminations cannot be obtained routinely. This implies that the apparent increase in young mothers over time could be more striking, because of the termination of some pregnancies in which fetuses had gastroschisis.
Although the increasing frequency in young mothers is not universal in all published studies,3 the relation between gastroschisis and young maternal age is consistently found in all of them. Some maternal or environmental risk factors related to young women seem to be changing with time in some areas of the world. This could be associated with many other changing factors. The way forward to deal with this challenge is collaborative research,1-3 if possible comparing factors in areas with and without increasing frequency of this rare congenital anomaly.
Competing interests: None declared.
References
- 1.Kilby DM. The incidence of gastroschisis. BMJ 2006;332: 250-1. (4 February.) [DOI] [PMC free article] [PubMed] [Google Scholar]
- 2.Donaldson L. Gastroschisis: a growing concern. London: Department of Health, 2004. www.dh.gov.uk/assetRoot/04/11/57/82/04115782.pdf (accessed 4 Jan 2006).
- 3.Martínez-Frías ML, Salvador J, Prieto L, Zaplana J. Epidemiological study of gastroschisis and omphalocele in Spain. Teratology 1984;29: 377-82. [DOI] [PubMed] [Google Scholar]
- 4.Martínez-Frías ML. Gastroschisis: is the prevalence increasing? Am J Med Genet 1994;49: 128. [DOI] [PubMed] [Google Scholar]
- 5.Martínez-Frías ML, Rodríguez-Pinilla E, Prieto L. Prenatal exposure to salicylates and gastroschisis: a case-control study. Teratology 1997;56: 241-3. [DOI] [PubMed] [Google Scholar]