The incidence and maternal age distribution of abdominal wall defects in Norway and Arkhangelskaja Oblast in Russia

Abstract

Objectives. To determine the foetal incidence of isolated anterior abdominal wall defects (gastroschisis and omphalocele) in the Arkhangelskaja Oblast (AO) in Russia and in Norway, as well as to study the maternal - age distribution of these defects.Study Design. A register - based incidence study.Methods. All registered foetuses and newborns with at least 12 weeks of gestation in the populations of AO (141,159) and Norway (293,708) were included. The data covered the period 1995–2004 in AO and 1999–2003 in Norway and were obtained from the malformation register in AO and the Medical Birth Registry of Norway.Results. The majority of the outcomes with a defect were liveborn in Norway (65%), while in AO the majority were spontaneously or medically aborted (59%). The incidence of anterior abdominal wall defects was 5.4/10,000 (95% confidence limits: ±1.7) in AO and 5.1/10,000 (±0.8) in Norway, and the ratio of omphalocele to gastroschisis was 1.2 in AO vs. 0.9 in Norway. Gastroschisis was inversely associated with maternal age in Norway.Conclusions. Despite a difference in maternal age distribution, there was no difference in the incidence of abdominal wall defects in AO and Norway. Gastroschisis was associated with young maternal age only in Norway, and the higher incidence in maternal age groups younger than 25 warrants further studies about aetiological factors associated with young maternal age.