Guiding Gestational Diabetes Treatment Through Ultrasounds

  • August 13, 2021

Uncontrolled gestational diabetes mellitus (GDM) management has been associated with poor neonatal outcomes such as increased birth weight, macrosomia, and neonatal hypoglycemia.  Fetal size is used to guide the management of gestational diabetes.  However, aggressive glucose control may lead to small-for-gestational-age (SGA) infants, placing them at an increased risk for adverse outcomes; while overestimation of fetal weight may place infants at an unnecessary risk for cesarean delivery.  Previous randomized clinical trials have been able to identify pregnancies at risk for fetal macrosomia.  Still, a clear association on the impact of ultrasound-guided management in routine clinical practice has not been assessed.  Therefore, a retrospective cohort study at a birthing hospital in Brisbane, Australia, was conducted to provide a clear management strategy.

Researchers targeted a population of primiparous women with a GDM diagnosis between 24-34 weeks’ gestation.  Women were excluded if they had a pregnancy with multiples, any congenital anomalies, or any significant medical comorbidities, medication use, or hospitalization post-diagnosis.  Ultrasound-guided management was classified as evidence of assessing fetal growth appropriateness and making subsequent changes for abnormal results.  Changes could include deviations from glycemic targets, changes to diet, or adjustments in pharmacotherapy.  A total of 221 women were included in the study, with 134 women classified in the ultrasound-guided management group and 87 women in the non-ultrasound-guided management group.  All ultrasounds assessed absolute and percentile measures of biparietal diameter, head circumference, A.C., femur length, and EFW.  Researchers conducted the statistical analysis with student t-tests, chi-square tests, Mann-Whitney U tests, Fisher’s exact tests, and logistic regression for potential confounding variables.

This study found no differences in neonatal birth weight, gestational age at birth, or size-for gestational age between both groups.  However, women in the ultrasound-guided management group were less likely than those in the non-ultrasound-guided management group to have a neonate with hypoglycemia at birth (unadjusted p=0.046, adjusted p=0.095).  Furthermore, fewer neonates were required a longer than five-day hospital stay (unadjusted p=0.010, adjusted p=0.032) or special care nursery or intensive care nursery admission (unadjusted p=0.004, adjusted p=0.011) in the ultrasound-guided management group.  Infants not undergoing ultrasound-guided management were more likely to receive phototherapy (3.7% vs. 11.5%) and antibiotics (21.6% vs. 36.8%) after birth.  Although nonsignificant, there were lower rates of SGA infants and larger-for-gestational age (LGA) infants in the ultrasound-guided management group.

A limitation of this study is its low external validity as only medically well, primiparous women with singleton pregnancies were included.  Risk factors for adverse neonatal outcomes include a history of GDM and a history of an LGA infant.  However, due to the healthy nature of the women included in this study, the risk was already reduced, limiting other women’s generalizability.  Furthermore, management strategy was dependent on clinician notes; therefore, guideline adherence may not reflect what was written in the patient notes.  Physician care may also have varied between patients depending on clinical expertise, impacting neonatal outcomes.  Previous studies have guided the adjustment of therapy, while in this study, adjustments were made based on personal preference.  Lastly, the small sample size of this study limits its statistical power.  Larger studies will need to be conducted to determine the clinical impact of ultrasound-guided management and, subsequently, its incorporation into guidelines.  However, this study’s strength was its ability to adjust GDM management in patients at risk for having an SGA infant.  In contrast, previous studies focused on altering management for an LGA infant. Altogether, this study showed the beneficial impact of ultrasound-guided management on neonatal outcomes.

REFERENCE:  Diabetes In Control; 22 MAY 2021; David L. Joffe, BSPharm, CDE, FACA

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