Pancreas agenesis and fetal growth: a semiquantitative analysis

Abstract

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. Semiquantitative 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, birth 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 birth 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. Significance statement Neonates with complete pancreas agenesis are born small, but the details of their growth deviation, timing, and potential sex differences remain uncertain. All neonates with pancreas agenesis in our study had reduced birth weight, length, and head circumference, with milder effects in those born before 36 weeks compared to after 36 weeks. This trend persisted when data were separated into before and after 38 weeks, with no discernible sex differences. The absence of the pancreas, and therefore insulin, significantly reduces fetal growth, especially after 36 weeks of gestation. In addition to insulin’s known role in fetal fat mass, our findings suggest it has a substantial influence on birth length and head circumference, underscoring its impact on fetal lean body growth.