A large-scale study analyzing data from over 4.7 million Chinese women has revealed that low blood sugar levels (hypoglycemia) before conception may be linked to an increased risk of adverse pregnancy outcomes, including preterm birth, low birth weight, and birth defects. The study was conducted by Wu and colleagues and published in the open-access journal PLOS Medicine.
While hyperglycemia is already known to pose risks during pregnancy such as gestational diabetes, large birth weight, and birth complications, low glucose levels have not been studied as extensively, particularly in the preconception period. This study aimed to fill that gap by analyzing data from the National Free Preconception Checkup Project, a government-supported initiative providing free health screenings to women planning to conceive. Between 2013 and 2016, data from 4,866,919 women were collected and retrospectively analyzed to assess the association between preconception hypoglycemia and pregnancy outcomes.
Among the participants, 239,128 women were identified as having hypoglycemia before conception. Compared to those with normal fasting plasma glucose (FPG) levels, women with preconception hypoglycemia showed a significantly increased risk of several adverse pregnancy outcomes. These included higher rates of preterm delivery, low birth weight, and congenital anomalies in newborns. The study also found that the impact of preconception hypoglycemia varied depending on the body mass index (BMI) of the women. Those categorized as underweight were more prone to miscarriages, whereas overweight women with hypoglycemia had a reduced risk of delivering babies that were large for gestational age. These findings highlight the complex interplay between glucose metabolism, nutritional status, and reproductive health.
In addition to identifying risk, the study shed light on demographic patterns. Women with preconception hypoglycemia were more likely to be younger and underweight than those with normal glucose levels. This suggests that nutritional deficiencies or metabolic imbalances might contribute to the observed trends and emphasizes the need for tailored preconception care.
Gong et al, in their multicenter prospective cohort study, found that recurrent severe hypoglycemia before conception was significantly associated with higher risks of preeclampsia, preterm birth, neonatal hypoglycemia, and other adverse neonatal outcomes, suggesting that hypoglycemia, regardless of diabetic status, may contribute to compromised maternal-fetal health.
The authors emphasize that while preconception hyperglycemia has received significant attention in clinical settings, hypoglycemia should not be overlooked. The study advocates for the inclusion of hypoglycemia in routine preconception glycemic screenings to enhance the early identification of at-risk women and to guide targeted interventions.
Despite its large sample size and robust dataset, the study acknowledges some limitations. These include a lack of data from non-Chinese populations and incomplete information on gestational complications, which could further elucidate the relationship between blood glucose levels and pregnancy outcomes. Future studies with more diverse populations and comprehensive clinical data are needed to validate and extend these findings
This research underscores the importance of comprehensive preconception health assessments, including screening for both hyperglycemia and hypoglycemia. Early detection and intervention may provide an expanded window for improving maternal and fetal health outcomes, particularly in women who may not present with overt symptoms or known metabolic conditions.
References
- Wu H, Yang Y, Zhao C, Lyu X, Li J, Lei J, et al. Preconception hypoglycemia and adverse pregnancy outcomes in Chinese women aged 20–49 years: A retrospective cohort study in China. PLOS Medicine. 2025 Jul 29;22(7):e1004667.
- Gong Y, Luo S, Shi J, Wei T, Wang J, Liu Y, et al. Preconception episodes of severe hypoglycemia and risk of adverse pregnancy outcomes in pregnant women with type 1 diabetes mellitus. Diabetes/Metabolism Research and Reviews. 2024;40(3):e3741.