Association between cell‐free DNA fetal fraction and gestational diabetes

Objective To determine the association between cell‐free DNA (cfDNA) fetal fraction and gestational diabetes (GDM) in a cohort of women presenting for cfDNA screening for fetal aneuploidy. Methods A retrospective cohort study of women with singleton pregnancies who had cfDNA screening at a single institution at 10 to 20 weeks gestation between October 2011 and October 2017. Fetal fractions were adjusted for gestational age (GA) using multiples of the median (MoM). Multivariable logistic regression was used to estimate the odds ratio (OR) of GDM controlling for potential confounders. Results Two thousand six hundred twenty‐three pregnancies met criteria. Women with GDM had a lower fetal fraction (0.93 MoM vs. 1.05 MoM, P = .002). However, the association between fetal fraction and GDM was not significant after adjusting for body mass index (BMI) [OR 0.84, 95% confidence interval (CI) 0.52‐1.36; P = .48]. Since insulin resistance increases at later GAs, separate analysis on women with GA 14 to 20 weeks was performed. Again, the association between fetal fraction and GDM was not significant after adjusting for BMI, (OR 0.81, 95% CI 0.31‐2.12; P = .67). Conclusion Low or high fetal fraction of cfDNA was not associated with GDM. Although fetal fraction was lower among women diagnosed with GDM, this relationship was no longer statistically significant once maternal BMI was taken into account.