Low Blood Sugar Before Pregnancy May Raise Risk of Preterm Birth, Low Birth Weight: Study Finds - Video

Women with low blood sugar levels before conception may face an increased risk of adverse pregnancy outcomes, according to a new study published in PLOS Medicine. The large-scale analysis draws from health data on more than 4.7 million Chinese women and sheds light on the implications of preconception hypoglycemia.

Glucose serves as the body’s primary energy source, and maintaining normal levels is essential for overall health. While the risks of high and low blood sugar during pregnancy are well-documented, little is known about the potential effects of low blood sugar (hypoglycemia) before pregnancy in women without pre-existing diabetes. Previous studies have mainly focused on hypoglycemia during pregnancy, leaving a knowledge gap that this study aimed to fill.

Researchers conducted a retrospective analysis using data from the National Free Preconception Checkup Project, a government-supported health initiative in China. Between 2013 and 2016, they reviewed health records of 4,866,919 women planning to conceive, including 239,128 women identified with preconception hypoglycemia. Their pregnancy outcomes were then compared to those with normal blood glucose levels.

The analysis found that women with hypoglycemia before pregnancy were more likely to experience adverse outcomes such as preterm birth, low birth weight, and birth defects. These women were generally younger and more likely to fall into the underweight BMI category. Interestingly, the impact of hypoglycemia varied with BMI: underweight women faced a higher risk of miscarriage, while overweight women had a reduced risk of delivering a baby large for gestational age.

The authors state, “In addition to paying attention to women with preconception hyperglycemia, our findings call for increased concern for women with hypoglycemia in preconception glycemic screening. These findings emphasize the importance of preconception examination in preventing and managing reproductive health risks for all women planning to conceive, and 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.”

Reference: u H, Yang Y, Zhao C, Lyu X, Li J, Lei J, et al. (2025) Preconception hypoglycemia and adverse pregnancy outcomes in Chinese women aged 20–49 years: A retrospective cohort study in China. PLoS Med 22(7): e1004667. https://doi.org/10.1371/journal.pmed.1004667