• pre-existing diabetes;
  • preterm birth;
  • small-for-gestational age;
  • large-for-gestational age;
  • pre-eclampsia;
  • race;
  • non-Hispanic blacks;
  • Hispanics;
  • South Asians;
  • education



More women are entering pregnancy with pre-existing diabetes. Disease severity, glycaemic control, and predictors of pregnancy complications may differ by race/ethnicity or educational attainment, leading to differences in adverse pregnancy outcomes.


We used linked New York City hospital record and birth certificate data for 6291 singleton births among women with pre-existing diabetes between 1995 and 2003. We defined maternal race/ethnicity as non-Hispanic white, non-Hispanic black, Hispanic, South Asian, and East Asian, and education level as <12, 12, and >12 years. Our outcomes were pre-eclampsia, preterm birth (PTB) (<37 weeks gestation and categorised as spontaneous or medically indicated), as well as small-for-gestational age (SGA) and large-for-gestational age (LGA). Using multivariable binomial regression, we estimated the risk ratios for pre-eclampsia, SGA, and LGA. We used multivariable multinomial regression to estimate odds ratios (OR) for PTB.


Compared with non-Hispanic white women with pre-existing diabetes, non-Hispanic black and Hispanic women with pre-existing diabetes had a 1.50-fold increased risk of pre-eclampsia compared with non-Hispanic whites with pre-existing diabetes, after full adjustment. Non-Hispanic black and Hispanic women with pre-existing diabetes had adjusted ORs of 1.72 [adj. 95% confidence interval (CI) 1.38, 2.15] and 1.65 [adj.95% CI 1.32, 2.05], respectively, for medically indicated PTB. South Asian women with pre-existing diabetes had the highest risk for having an SGA infant [adj. OR: 2.29; adj. 95% CI 1.73, 3.03]. East Asian ethnicity was not associated with these pregnancy complications.


Non-Hispanic black, Hispanic, and South Asian women with pre-existing diabetes may benefit from targeted interventions to improve pregnancy outcomes.