Low blood sugar before conceiving may lead to negative pregnancy outcomes

A study involving more than 4.7 million Chinese women reveals that those who had hypoglycemia (low blood sugar levels) before conceiving a child were more likely to have certain adverse pregnancy outcomes. These included their baby being born preterm or with low birth weight. 

The findings build on previous research highlighting that women who are hyperglycemic (high blood sugar, found in prediabetes and type 2 diabetes) before or during pregnancy are more likely to face adverse pregnancy outcomes.

However, there has been little data revealing whether hypoglycemia detected before pregnancy is linked to negative pregnancy results for women without pre-existing diabetes.

“In addition to paying attention to women with preconception hyperglycemia, our findings call for increased concern for women with hypoglycemia in preconception glycemic screening,” say the authors.

“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 fasting plasma glucose prior to and during pregnancy, which is crucial for advancing the intervention window and mitigating the risk of adverse pregnancy outcomes.”

Assessing pregnancy risks

Hanbin Wu of the Chinese University of Hong Kong, in collaboration with the National Research Institute for Family Planning, retrospectively analyzed data on 4,866,919 Chinese women from the National Free Preconception Checkup Project, a free health service for women planning to conceive.

Looking at data from 2013 to 2016, they studied the correlations between preconception hypoglycemia and pregnancy outcomes.

The authors encourage that women trying to conceive get tested for preconception hypoglycemia.The researchers note that 239,128 of the women had preconception hypoglycemia. Compared to those with normal preconception blood sugar, they had a higher risk of adverse pregnancy outcomes like preterm birth, low birth weight, or birth defects.

The women with hypoglycemia also tended to be younger than those who had normal blood sugar levels and were more likely to have a body mass index (BMI) categorized as “underweight.”

However, the pregnancy risks associated with preconception hypoglycemia varied for women with different BMIs. For example, the researchers note that underweight women had a higher risk of miscarriage, while the overweight participants had a lower risk of their baby being large for their gestational age.

Based on their findings, the authors suggest that women trying to conceive get tested for preconception hypoglycemia.

They say additional research may address some limitations of this study, such as by including women from other countries and more information on patients’ gestational complications. Their paper is published in PLOS Medicine.

In other maternal health research, a recent Danish study found a “strong link” between eating a Western diet during pregnancy and neurodevelopmental disorders such as ADHD and autism in children. The observational paper suggests mothers’ dietary interventions can potentially reduce these risks.