Mothers with a rare genetic form of diabetes (HNF1A-MODY) are nearly four times more likely to deliver large-for-gestational-age babies when their blood sugar runs high during pregnancy — and the baby's own genetic status doesn't fully explain it. A retrospective Irish study found that insulin treatment helped, but didn't eliminate the risk. Neonatal hypoglycemia also occurred almost exclusively in babies born to affected mothers.
A new study out of Ireland sheds light on pregnancy risks tied to HNF1A-MODY, a rare inherited form of diabetes. Researchers found that babies born to mothers with the condition were far more likely to be large for gestational age (LGA) compared to babies born to affected fathers — and elevated maternal blood glucose during pregnancy was the key driver, even after accounting for whether the baby inherited the mutation.
The retrospective study reviewed 183 pregnancies from 1965–2023 and found that insulin treatment reduced LGA births, but didn't eliminate the risk entirely. Babies born to mothers with uncontrolled glucose were especially vulnerable, and neonatal hypoglycemia — sometimes severe enough to require NICU admission — occurred almost exclusively in the maternal-inheritance group.
By the Numbers:
Why it matters: For OB and neonatal teams, this research underscores the importance of proactive glucose management in pregnant women with HNF1A-MODY and early counseling around perinatal risks — regardless of whether the baby carries the mutation.
