# Sirenomelia With Complete Caudal Regression in a Preterm Infant Born to a Mother With Poorly Controlled Type 1 Diabetes Mellitus: A Case Report on Clinical Presentation and Perinatal Management Challenges

## TL;DR

A preterm infant with severe birth defects linked to uncontrolled maternal diabetes highlights the importance of preconception care.

## Contribution

A case report linking poor maternal glycemic control to sirenomelia and highlighting perinatal management challenges.

## Key findings

- Sirenomelia with complete caudal regression occurred in a preterm infant of a mother with poorly controlled type 1 diabetes.
- The infant had multiple severe malformations, including bilateral renal agenesis, leading to death within 24 hours.
- The case underscores the need for optimal preconception glycemic control to prevent severe fetal anomalies.

## Abstract

Sirenomelia is a rare, lethal congenital anomaly characterized by caudal regression and lower limb fusion. The etiopathogenesis is multifactorial, with maternal glycemic dysregulation established as a significant risk factor, contributing to the development of this severe malformation syndrome.

We report an infant born at 33 weeks' gestation with a birth weight of 1,900 g to a 36-year-old multiparous woman with poorly controlled type 1 diabetes mellitus (HbA1c, 9.8%). Prenatal ultrasound evaluation during the second trimester identified significant fetal abnormalities consistent with a lethal congenital malformation syndrome. The neonate presented with complete lower limb fusion, bilateral renal agenesis, imperforate anus, ambiguous genitalia, and dysmorphic facial features. Despite supportive palliative care, the infant died at 24 hours of life due to complications of bilateral renal agenesis and associated malformations.

This case emphasizes the critical importance of optimal preconception glycemic control in diabetic women and highlights the challenges in prenatal counseling and neonatal management of sirenomelia. The case contributes to the growing evidence linking poor maternal glycemic control with severe caudal regression anomalies and underscores the need for enhanced periconceptional counseling.