AsianScientist (Sep. 10, 2025) – Blood sugar levels are usually associated with diabetes, but new research shows they can also play a crucial role in pregnancy outcomes. A large-scale study from China has found that women with low blood sugar levels before pregnancy may face a higher risk of complications such as preterm birth and low birth weight.
Glucose, a type of sugar and the body’s primary source of energy, plays a vital role in maintaining health. Both high blood sugar (hyperglycemia), commonly seen in prediabetes and type 2 diabetes, and low blood sugar (hypoglycemia) are known to pose risks.
Earlier studies have shown that high blood sugar before or during pregnancy increases the risk of complications, and that low blood sugar during pregnancy is also linked to adverse outcomes. However, it was unclear whether low blood sugar before pregnancy posed risks for women without pre-existing diabetes.
To address this gap, Hanbin Wu, researcher at the Chinese University of Hong Kong, in collaboration with the National Research Institute for Family Planning in Beijing, conducted a large retrospective study using data from the National Free Preconception Checkup Project, a free health service for women planning to conceive.
The researchers analyzed data of 4,866,919 Chinese women aged between 20 to 49 who had enrolled in the national checkup project between 2013 and 2016. Of these, nearly 240,000 were found to have hypoglycemia prior to conception.
The study found that women with low blood sugar pre-pregnancy had higher risks of adverse pregnancy outcomes, including preterm birth, low birth weight, and birth defects.
“In addition to paying attention to women with preconception hyperglycemia, our findings call for increased concern for women with hypoglycemia in preconception glycemic screening,” the authors stated in the study, published in PLOS Medicine.
Risks vary by body type
The researchers also found that women with hypoglycemia tended to be younger than those with normal blood sugar levels and were more likely to have BMIs in the “underweight” category.
However, the risks associated with pre-pregnancy hypoglycemia varied for women with different BMIs. Underweight women were more likely to face miscarriage, while overweight women with hypoglycemia were less likely to give birth to babies who were larger than average for their gestational age.
Based on the findings, the researchers suggest that including screening for hypoglycemia in the preconception stage may help reduce risks and improve pregnancy outcomes.
“These findings also highlight the necessity of comprehensive screening and coordinated interventions for abnormal FPG (fasting plasma glucose) prior to and during pregnancy, which is crucial for advancing the intervention window and mitigating the risk of adverse pregnancy outcomes,” the authors stated.
However, the researchers also caution that further study is needed as their analysis was limited to Chinese women, and future studies across different populations could help determine whether the findings are consistent worldwide.
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Source: The Chinese University of Hong Kong ; Image: Shutterstock
The Study can be found at: Preconception hypoglycemia and adverse pregnancy outcomes in Chinese women aged 20–49 years: A retrospective cohort study in China
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