1. The birth prevalence of Hirschsprung disease (HSCR) from 1987 to 2012 in Sweden was found to be steady at approximately 1 in 5000 with a male predominance.
2. Significantly more babies with HSCR were born prematurely compared to healthy controls and data suggested maternal obesity as a risk indicator.
Evidence Rating Level: 3 (Average)
Study Rundown: HSCR is a multifactorial disease caused by an absence of nerve cells in the distal colon or, in the most severe cases, across the entire large intestine. Clinically, this leads to impaired peristalsis, which slows or blocks the passage of stool, resulting in intestinal obstruction and risk for infection. Although multiple susceptibility genes have been identified for HSCR, less is known about the environmental influences. To study the maternal risk factors and infant characteristics associated with HSCR, investigators performed a population-based case-control study in Sweden. The birth prevalence was computed to be 1.91/10 000, and the male-to-female ratio of HSCR cases was found to be 3.7:1. Of the maternal risk factors considered, including maternal age, smoking habits, body mass index (BMI), parity, and diseases (such as diabetes), only maternal obesity was significantly associated with increased risk of HSCR. Additionally, it was found that babies with HSCR were more often born preterm (< 37 weeks’ gestation). Lack of statistical power may have prevented the detection of additional significant associations, particularly with regard to maternal diseases. Further, due to the relatively strict inclusion criteria, it is possible that less severe forms of HSCR were not included. Despite these limitations, this study identifies yet another disease for which obesity may be a risk factor, further emphasizing the importance of addressing this global epidemic.
Relevant Reading: Hirschsprung disease, associated syndromes and genetics: a review
In-Depth [case-control study]: Participants included all babies born in Sweden from January 1, 1982 through December 31, 2012 and registered in the Swedish Medical Birth Register (MBR). Data in the MBR included maternal characteristics such as age, height, and weight, in addition to information regarding the pregnancy, such as duration and birth weight. Using unique personal identification numbers, these metrics were linked to pediatric hospital admissions and diagnoses listed in the Swedish National Patient Register (NPR). The inclusion criteria for cases of HSCR required not only HSCR diagnosis, but also a documented HSCR-specific surgical procedure in conjunction with a defined set of pediatric hospital admission requirements. A total of 600 children (466 boys and 134 girls) met these inclusion criteria. For analysis, each case was randomly assigned 5 age- and sex-matched controls. The risk of HSCR was found to be greater among women with BMI ≥30.0 (unadjusted OR = 1.74; 95%CI: 1.25-2.44). Although only trending toward significance in the full analysis, a subanalysis of male cases suggested that parity ≥3 might also be associated with HSCR (male subgroup: unadjusted OR = 1.30; 95%CI: 1.01-1.68). Gestational age <37 weeks was also significantly associated with HSCR diagnosis (unadjusted OR = 1.60; 95%CI: 1.18-2.17). While one might think that caesarean delivery may have been more common in pregnancies of babies with HSCR, no association was found with delivery mode. Additional congenital malformations and/or chromosomal abnormalities were found in 34.5% of the HSCR cases, including 59 individuals (9.8% of the cases) with Down syndrome.
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