Data collection
The demographic information and baseline characteristics including age,
pre-pregnancy weight and height (pre-BMI calculated,
kg/m2), final weight at delivery, blood pressure,
gravidity, parity, history of disease (cardiovascular disease, diabetes
mellitus, chronic hypertension and etc.), degree of education,
profession, smoking and drinking habits, was collected by questionnaire.
According to China cutoff points, pregnant women were classified as low
weight (BMI < 18.5 kg/m2), normal weight
(18.5 kg/m2 ≤ BMI ≤ 23.9 kg/m2) or
overweight & obese (BMI ≥ 24.0 kg/m2). Gestational
weight gain (GWG) was calculated as the difference value between final
weight at delivery and pre-pregnancy weight. Gestational age was
determined by combination of the last menstrual period and the early
first trimester ultrasound. The diagnosis of GDM was made by the
criterion of the International
Association of the Diabetes and Pregnancy Study Groups (IADPSG): one or
more of the following values is met or exceeded in the 75g Oral Glucose
Tolerance Test (OGTT): fasting glucose, 5.10 mmol/L; 1-h glucose, 10.00
mmol/L; 2-h glucose, 8.50 mmol/L.