Frequency of gastroschisis and omphalocele and possible influence of maternal folic acid supplementation. A narrative review

There is an increase in the worldwide prevalence of congenital abdominal wall defects (CAWD), with gastroschisis (GS) and omphalocele (OC) being the most common. It is widely accepted that folic acid supplementation (FAS) in the maternal diet decreases the incidence of anomalies such as neural tube defects, but there is controversy regarding the possible beneficial role for other congenital malformations. Several epidemiological studies raise controversy regarding a possible relationship between vitamin supplementation with the occurrence of abdominal wall malformations. The aim of the present study is to obtain an updated review of the global frequency of CAWD in neonates and the relationship with FAS in the mothers. For this we have carried out a systematic search of epidemiological studies in different article databases between 2011 and 2022. The analysis of 25 studies conducted in different countries where cases of OC and/or GS are registered directly or together with other congenital defects shows that 60% inquire into the relationship of FAS with the incidence of CAWD. Half of them proposes a beneficial effect of FAS and the other half find no association, concluding that there is no unanimous evidence that FAS in the maternal diet decreases the incidence of CAWD. However, it seems that an influential factor to take into account is the nutritional habits of the mothers.