An age matched case-control study on the risk factors for the gestational diabetes mellitus among primiparous women.

OBJECTIVES Gestational diabetes mellitus (GDM) is one of the most common complications of pregnancy. It is associated with a wide range of short and long term adverse health consequences for both mother and offspring. As we know, the risk factors of the GDM are complex and diverse, and the incidence of GDM is directly correlated with the age and the times of women delivery. In the process of exploring the risk factors of GDM, if the 2 known independent risk factors are unevenly distributed among groups, the effects of other risk factors may be concealed. To avoid the influence of the 2 factors on the research results, we collected primiparous women as the participants through the method of the case-control study of age 1꞉1 paired design. Through this way, we want to provide early intervention for the pregnant women with the high risk factors so as to reduce the possibility of the GDM during the pregnancy and promote the maternal and infant's health. METHODS This study was a retrospective study. A total of 2 425 pregnant women were collected as the participants, who accepted the regular prenatal examination or nutrition health guidance in the Department of Obstetrics or Nutrition in the Women and Children's Hospital, School of Medicine, Xiamen University from August 2018 to October 2019. According to the inclusion and exclusion criteria, 2 287 pregnant women were included in the study. Among them, 231 pregnant women with the complete information were collected as a case group because of the abnormal results of the oral glucose tolerance test (OGTT) that executed between the 24th and 28th weeks during the pregnancy. Meanwhile, among the participants with the normal results of the OGTT, 231 pregnant women with the complete information were selected randomly as a control group through the method of the age 1꞉1 paired with the case group. The age range of the all subjects was 22 to 45 (28.82±4.03) years old. We collected their clinical and basic data retrospectively, including the BMI before pregnancy, the level of uric acid, fasting blood glucose, serum lipid index, and glycosylated hemoglobin (HbA1c) in the early pregnancy, the body weight gain before the 13th and 24th weeks during the pregnancy, the times of the abortions, the positive of HBsAg, the family history of diabetes or hypertension etc. The differences in these indexes were compared between the 2 groups. The logistic regression analysis was used to explore the risk factors for GDM and the stratified analysis was used to explore the difference of the body weight gain before the 24th week during the pregnancy between the 2 groups. RESULTS The BMI before pregnancy, the uric acid, the fasting blood glucose, the body weight gain before the 13th and 24th weeks during the pregnancy in the GDM group were higher than those in the control group, and the differences were significant (all P<0.05). The LDL level in the early pregnancy of the GDM group was higher than that of the control group, however, the HDL level in the early pregnancy of the GDM group was lower than that of the control group, and the differences were significant (both P<0.05). The rates of the pregnant women in the GDM group with more than 2 abortions, obesity or overweight before pregnancy, the fasting blood glucose in the early pregnancy over 5.1 mmol/L were significantly higher than those in the control group (all P<0.05). With the uptrend of the cut-off point of the body weight gain before the 24th week during the pregnancy, the risk of the GDM was gradually increasing. When the cut-off point reached at 10 kg, the difference was significant (OR=1.988, P=0.004). The level of HDL in the early pregnancy over 1.6 mmol/L was the protective factor for GDM (OR=0.460, P=0.016). Meanwhile, the body weight gain over 10 kg before the 24th week during the pregnancy (OR=1.743, P=0.032), the fasting blood glucose in the early pregnancy over 5.1 mmol/L (OR=3.488, P=0.001), the LDL in the early pregnancy over 2.5 mmol/L (OR=2.179, P=0.032) were the risk factors for the GDM. Among them, the fasting blood glucose in the early pregnancy over 5.1 mmol/L had the greatest impact on the increase of risk for the GDM. CONCLUSIONS After excluding the influence of the age, for primiparous women, the higher level of the LDL and the fasting blood glucose in the early pregnancy, the higher possibility to be the GDM. Meanwhile, the pregnant women should control their diet as soon as possible to control the body weight gain within 10 kg before the 24th week during the pregnancy so as to reduce the possibility of being GDM.