726 Fetal growth by ultrasound prior to the diagnosis of gestational diabetes mellitus in nulliparous women

Abstract

The timing of excess fetal growth in gestational diabetes mellitus (GDM) is uncertain. We therefore evaluated ultrasound patterns of fetal growth among women with and without GDM. Women in the NuMoM2b study who had their first GDM screening test after 24 weeks’ gestation and ultrasound biometry available from study visits 1 (between 16-22 weeks) and 2 (between 24-30 weeks) were included. Fetal growth parameters were compared between women with and without GDM. Reference values from the NICHD Fetal Growth Study was used to define estimated fetal weight and abdominal circumference 90th percentile. Multivariable logistic regression was used to assess the relationship between GDM and fetal growth. We also compared fetal growth parameters among women with normal GDM screening, mild glucose intolerance (defined as 1 abnormal OGTT value), and GDM. Of the 6,635 women included in this analysis, 265 (4.0%) had GDM. There were no differences in fetal growth at study visit 1 among women with and without GDM. By study visit 2, both estimated fetal weight and abdominal circumference >90th percentile were more common in women with GDM (Table 1). After adjusting for covariates, an abdominal circumference >90th percentile was more likely in women with GDM (Table 2). There were no differences in fetal abdominal circumference >90th percentile (aOR 1.0, 95% CI 0.6-1.5) or estimated fetal weight >90th percentile (aOR 1.1, 95% CI 0.8-1.5) between women without GDM and those with only one abnormal OGTT value. GDM was not associated with differences in ultrasound parameters of fetal growth in mid-pregnancy, but by 24-30 weeks’ a larger abdominal circumference was observed. Mild glucose intolerance did not impact fetal growth in either mid-pregnancy or at the start of the third trimester. Further studies are needed to assess the optimal timing of GDM screening and the level of maternal glycemia used for GDM diagnosis.View Large Image Figure ViewerDownload Hi-res image Download (PPT)