Prevalence, infant outcomes and gestational risk factors for transverse reduction deficiencies at or above the wrist: a population-based study.

We identified individuals born in Norway between 1970 and 2019 with transverse reduction deficiency at or above the wrist (TRDAW) from the Medical Birth Registry of Norway and from the CULA (congenital upper limb anomaly) North Oslo Registry. Infant outcomes and parental factors were compared for 202 individuals with TRDAW to 2,741,013 living individuals without TRDAW born during the same period. We found an overall TRDAW prevalence of 0.74/10,000. Infants with TRDAW had a higher risk for being small for gestational age, an Apgar score <7 and transfer to neonatal intensive care units after delivery. Nine of the infants with TRDAW had associated anomalies, most commonly in the lower limb, and at a higher proportion than the reference population. Other than twin pregnancies, we are unable to identify with certainty any other risk factors for TRDAW.Level of evidence: I.