Effect of preconception impaired glucose tolerance on pregnancy outcomes in women with polycystic ovary syndrome

Context: Women with polycystic ovary syndrome (PCOS) commonly have intrinsic insulin resistance and are recommended to undergo an oral glucose tolerance test (OGTT) for diabetes screening. However, the effect of preconception impaired glucose tolerance (IGT) on pregnancy is still unclear. Objective: To prospectively assess the effect of preconception IGT on pregnancy outcomes. Design, Setting, Patients, Interventions, and Main Outcome Measures: This was a secondary analysis of a multicenter randomized trial in 1508 women with PCOS comparing live birth and obstetric complications between fresh and frozen embryo transfer. At baseline, fasting and 2-hour glucose and insulin levels after 75-g OGTT were measured. Results: Women with preconception IGT had higher risks of gestational diabetes in both singleton pregnancy [9.5% vs 3.2%; odds ratio (OR) 3.13; 95% confidence interval (CI) 1.23to 7.69] and twin pregnancy (20.0% vs 3.2%; OR 7.69; 95% CI 2.78 to 20.00) than women with normoglycemia. Preconception IGT was associated with a higher risk of large for gestational age in singleton newborns compared with normoglycemia (34.7% vs 19.8%; OR 2.13; 95% CI 1.19 to 3.85) or isolated impaired fasting glucose (i-IFG) (34.7% vs 15.4%; OR 2.94; 95% CI 1.33 to 6.25). Women with preconception IGT had a higher singleton pregnancy loss rate than women with i-IFG (31.4% vs 17.5%; OR 2.17; 95% CI 1.11 to 4.17). After adjusting for age, body mass index, duration of infertility, total testosterone level, and treatment groups (frozen vs fresh embryo transfer), these associations remained. Conclusions: Preconception IGT, independent from BMI, was associated with adverse pregnancy outcome compared with i-IFG and normoglycemia.