Pancreas agenesis and fetal growth: a semi-quantitative analysis

Pancreas agenesis is a rare condition underlying a variant of permanent neonatal diabetes mellitus. Neonates with this condition are born small for gestational age, but less is known about which components of growth are impacted, the timing of the growth restriction and potential sex differences. Our objective was to assess in which periods in gestation complete pancreas agenesis restricts fetal growth and possible sex differences in susceptibility. Published cases (n=49) with pancreas agenesis providing relevant data (gestational age, fetal sex, birth weight, birth length, head circumference, placental weight) were identified by MEDLINE and secondary literature search covering the years 1950-January 2023. Semi-quantitative analysis of these case reports used centiles based on Intergrowth-21 reference charts. Neonates with pancreas agenesis were severely growth restricted, however, median centiles for birth weight, length and head circumference of those born before week 36 were significantly higher compared to those born from 36 weeks. Similar results were found when data were separated by before and from 38 weeks. Head circumference was less affected than birth weight or length. No sex differences were found. In conclusion, pancreas agenesis severely restricts fetal length and head circumference in addition to weight growth, with stronger effects evident from 36 weeks of gestation. In addition to the well-known effects of insulin on growth of fetal fat mass, the pronounced effect on birth length and head circumference indicates effects of insulin on fetal lean body growth as well. Lack of power may account for failure to find sex differences.