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High sugar levels in gestational diabetes are harmful to mother and baby
Last reviewed: 02.07.2025
The higher the blood sugar levels in pregnant women when diabetes is first diagnosed, the higher the risk of complications during and after childbirth, according to a study presented at the 26th European Congress of Endocrinology, held May 11-14 in Stockholm.
For every 5 mg/dL increase in blood sugar above the diagnostic threshold, the risk of low blood sugar in newborns or high birth weight increases by 9% and 6%, respectively, while the risk of developing diabetes after delivery increases by 31% in mothers. These findings suggest that women at high risk of developing gestational diabetes should be classified more specifically to limit these complications for mothers and newborns.
Gestational diabetes is a condition in which women have high blood sugar, or glucose, levels during pregnancy. It affects about 20 million pregnancies worldwide and poses increased health risks for both mothers and their babies. For example, mothers are more likely to develop type 2 diabetes and have particularly large babies, who are at high risk of birth injuries or even obesity later in life.
Women are diagnosed with gestational diabetes if their fasting blood glucose level is greater than 92 mg/dL in the first trimester or their 2-hour postprandial glucose level (OGTT) is greater than 153 mg/dL in the second trimester.
In this study, researchers from the Tamega i Sousa Hospital Centre in Portugal analysed data on blood sugar levels and birth complications in 6,927 pregnant women aged 30–37 who were carrying a single baby and were diagnosed with gestational diabetes between 2012 and 2017.
The researchers found that for every 5 mg/dL increase in blood sugar levels, the risk of low blood sugar ( hypoglycemia ) and large-for-gestational-age (LGA) in newborns increased by 9% and 6%, respectively, and the risk of hyperglycemia in mothers after delivery increased by 31%.
"While it is not surprising that high glucose levels are associated with these adverse maternal and neonatal outcomes, our study shows for the first time how much the risk increases with each 5 mg/dL increase in maternal blood glucose levels at initial diagnosis of gestational diabetes," said study co-author Dr. Catarina Cidade-Rodrigues.
Dr. Cidade-Rodrigues continued: "The magnitude of the increased risk can be calculated using our measurements and can be used in practice to identify and stratify women at higher risk of developing these complications."
"We now want to assess whether there is benefit in further stratifying these women at high risk of gestational diabetes, who will need closer monitoring and for whom pharmacological interventions can be given accordingly. This may help reduce complications during childbirth and in the newborn and prevent future diabetes in these women."