Association of irregular menstruation with gestational diabetes: Observations from a survey in university-affiliated medical centers in Tehran

Gestational diabetes is defined as carbohydrate intolerance of variable severity with onset or first recognition during pregnancy. Approximately 4% of pregnancies are affected by diabetes mellitus, 90% of which represent gestational diabetes mellitus (GDM). Detection of GDM permits the identification of women who are at risk for development of type 2 diabetes mellitus later in life. Appropriate treatment may reduce the risk of fetal and neonatal complications. One of the risk factors identified recently is "irregular menstruation". Several studies have reported the relationship between irregular menstruation and insulin resistance. The aim of this case-control study was determination of relationship between irregular menstruation and gestational diabetes.

Pregnant women who were referred to prenatal clinics affiliated to Endocrinology and Metabolism centers of Shariati and Taleghani hospitals, and Iran Endocrinology and Metabolism institute, were studied. Mothers were interviewed by trained members of the study team and relevant information recorded on a structured questionairre. Sampling was performed by convenience method. Case group including 60 women with gestational diabetes and control group comprising of 60 women without gestational diabetes were matched for age, parity, BMI, family history of diabetes, history of still-birth, or delivery of a previous malformed newborn. Demographic characteristics, history of irregular menstruation and its etiology were compared between the two groups. We excluded subjects with history of fetal macrosomia (weight>4500 g), pre-pregnancy diabetes, diabetes in previous pregnancy, smoking before or during pregnancy, recurrent abortion and preterm delivery.

Demographic characteristics and etiology of irregularity were similar between cases and controls. Irregular cycles were more prevalent in the case group, (36.7% vs. 15.0 %, P=0.007, Odds Ratio=3.28, CI=95%, 1.40-7.90 ).

A history of irregular menstrual cycles was a significant independent predictor of gestational diabetes mellitus. If selective screening is implemented for gestational diabetes mellitus, such history should be considered in the decision of whom to test.