Evaluation of the Incidence of Gestational Diabetes Mellitus and Some Other Pregnancy Outcomes in Women with Abnormal Fasting Plasma Glucose in the First Trimester of Pregnancy

Background and purpose: Due to specific metabolic changes during pregnancy, identifying pregnancy risks and timely intervention can improve the health of the mother and baby. The best results for preventing gestational diabetes are achieved through lifestyle measures early in pregnancy. Today, abnormal fasting plasma glucose (FBS) is routinely measured in early pregnancy, but its association with pregnancy outcomes is ambiguous. This study aims to investigate the incidence of gestational diabetes mellitus and other pregnancy outcomes in women with FBS levels in the first trimester of pregnancy. Materials and methods: This prospective descriptive study was conducted on 230 women with singleton pregnancies at the clinic of Imam Khomeini Hospital in Sari in 2022. After obtaining informed consent, blood samples were collected from pregnant women in the first trimester of pregnancy, and FBS levels were recorded. Additionally, between the 24th and 28th weeks of pregnancy, women underwent a re-examination based on the results of the 75g glucose tolerance test (OGTT). Based on FBS levels, women were divided into two groups: normal (92-100 mg/dL) and abnormal (101-126 mg/dL). All mothers were followed up during pregnancy, and on average, 2 days after giving birth, the pregnancy outcomes of both the mother and the baby were recorded. Data were analyzed using SPSS version 22 software. Results: The mean and standard deviation of mothers' age in the mothers of the normal FBS group were 31.05 ± 5.61 years, and in the mothers of the abnormal FBS group, it was 32.46 ± 6.24 years. The number of pregnancies in 64% (n=80) and 51.4% (n=54) of mothers was less than or equal to two pregnancies, and the number of deliveries was less than or equal to 2 births in 75.2% (n=94) and 66.7% (n=70) respectively. The most common underlying disease was hypothyroidism, which was present in 20% of mothers with normal FBS and 21% of mothers with abnormal FBS. The results showed that in weeks 24 to 28 of pregnancy, 56.5% (n=130) of mothers had impaired oral glucose tolerance tests, which was statistically significant (P=0.048). The relationship between stillbirth (P=0.593), IUGR fetus (P=0.392), blood pressure disorders related to pregnancy (P=0.904), neonatal hypoglycemia (P=1), liquid ammonia level in the 28th week of pregnancy (P=0.915) and the 36th week of pregnancy (P=0.537), and the Apgar score of the first minute (P=0.514) and the fifth minute (P=0.296) were not significant with abnormal FBS in the first pregnancy. There was a substantial relationship between impaired OGTT and first-pregnancy FBS, and 69.5% of mothers with first-pregnancy FBS in the range of 101-126 mg/dL had impaired OGTT (P<0.0001). Also, the type of cesarean delivery (P=0.037) insulin intake (P=0.031), and gestational age less than 37 weeks at the time of delivery (P=0.047), had a significant relationship with the first FBS of pregnancy. Conclusion: The results showed that FBS in the first trimester is related to gestational diabetes and pregnancy outcomes and can be used as a simple and low-cost screening test to identify pregnancies at risk of GDM and some adverse pregnancy outcomes, including the type of delivery. Insulin and gestational age should be assessed at the time of delivery.