Risk of Fetal Anomalies and Its Prevalence by Ultrasonography in Pregnancies Complicated by Well Controlled Pre-gestational Diabetes Mellitus

Diabetes mellitus is being diagnosed in 0.3% of women at the reproductive stage of their life. Prevalence in Srilanka around 10% of the urban population. The prevention of congenital malformations in the newborns of pre-gestational diabetic mothers still constitutes one of the main problems in this group of patients in Srilanka. Objectives: 1. To analyze the prevalence of fetal malformations in pre-gestational diabetic pregnancies compared to uncomplicated non diabetic pregnancies. 2. To evaluate the clinical utility of a comprehensive program inclusive of clinical features, glycemic assessment and prenatal detailed ultrasound with fetal echocardiography for congenital anomalies in pregnancies complicated by diabetes mellitus. Methodology: Study design: Hospital based prospective cohort study. Study setting: De Soyza maternity hospital- Colombo, Sri Lanka. Study period: August 2006 to August 2008. Study population: 789 pre-gestational diabetic women who were registered in hospital clinics during Aug 2006 to Aug 2008 and their newborns. The results were compared with age and parity matched low risk non diabetic population of 780 antenatal mothers. Study Instruments: Interviewer administered questionnaire included detailed history, examination checking glycemic assessment and comprehensive fetal ultrasonography inclusive of a standard four-chamber view of the heart and detailed power Doppler fetal echocardiography according to ISUOG standards. Glycemic control was set at 90-130mg/dl at pre and post prandial values and target HbA1C was set at below 6.2%. Data collection: The purpose of the study was explained to the pregnant women and informed written consent was taken. Data analysis: using the Statistical Package of Social Sciences (SPSS), version 17.0, did Data entry and analysis. Results: Anomalies were identified in 49 of 789 (6%) fetuses and neonates: 12 central nervous system, 03 abdominal wall defects, 03 diaphragmatic hernias, 08 renal tract defects, 03 cystic hygromas, 02 isolated hydrothorax, 04 hydrops with multiple congenital abnormalities, 04 gastro intestinal malformations, 02 limb defects and 04 cardiac abnormalities were detected prenatally. 03 cardiac lesions 02 limb defect (VACTERAL) and down syndrome fetus detected postnatally. The results were compared with age and parity matched non diabetic control group of 780 routine visits mothers and antenatal admissions having 21/780 (2.7%) with only 1 cardiac abnormality this was significant p < 008 at (95% CI 0.77 - 5.03). Central nervous system defects including hydrocephalus, holoporencephaly, encephalocele accounted for nearly 25% of total anomalies and renal tract abnormalities 15% all these anomalies in all systems except 3 cardiac and 2 limb defects were detected prenatally. Cardiac abnormalities including cardiac septum and great vessels, accounted for 15% of all fetal defects of which only 72% detected prenatally. Missed lesions were detected at neonatal 2D echo and these included a large ASD, a ventricular septal defect and PDA. There were seven neonatal deaths and five therapeutic pregnancy terminations associated with congenital anomalies. There were three fetal interventions done on 2 isolated renal obstructive uropathy and one hydrothorax with a success of 50%. Recommendations and conclusion: This study demonstrates confirm the view that pre-gestational diabetic pregnancy, despite the improved metabolic control, is still a strong risk factor for alterations in fetal development leading to fetal malformations. This study also demonstrate the advantage of a comprehensive program to detect fetal anomalies in pregnancies complicated by pre-gestational diabetes mellitus focusing further attention towards detecting fetal cardiac abnormalities.