High blood sugar or diabetes during pregnancy tied to abnormal fetal growth: JAMA

China: In order to ensure normal fetal growth, pregnant women should not only prevent and control gestational diabetes but also avoid increased blood sugar levels in late pregnancy, suggests a recent study. This is especially for women with high blood sugar levels throughout pregnancy. 

The study, published in JAMA Network Open, found that pregnant women with a diagnosis of gestational diabetes in mid-pregnancy or having hyperglycemia during all 3 trimesters showed an association with altered fetal growth patterns, including increased birth weight, increased estimated fetal weight that appeared before a gestational age of 24 weeks, and the risk for large size for gestational age and macrosomia. 

There is a lack of evidence on the timing of fetal growth tied to gestational diabetes or on the association of the maternal glycemic trajectory with fetal growth during pregnancy. To fill this knowledge gap, Jiao-jiao Zou, Fudan University, Shanghai, China, and colleagues aimed to examine the associations between maternal glucose levels and offspring intrauterine growth in a cohort study.

The study used data from 4574 eligible pregnant women and their offspring in the Shanghai Maternal-Child Pairs Cohort. Data was collected from April 10, 2016, to April 30, 2018. To classify fasting plasma glucose levels during pregnancy into 3 glycemic trajectories, group-based trajectory modeling was used (trajectory 1, consistently normal glucose levels in all 3 trimesters; trajectory 2, hyperglycemia only in late pregnancy; and trajectory 3, hyperglycemia in all 3 trimesters [ie, consistently high glucose levels]). 

Gestational diabetes was defined using the results of an oral glucose tolerance test. 

The researchers obtained longitudinal fetal biometrics during gestational weeks 11 to 40 and birth outcomes using medical records. Pregnancy was divided into 3 periods (<24, 24-34, and >34 weeks' gestational age). Comparison between differences in offspring growth (log-transformed) and maternal glucose levels using generalized linear mixed models. 

 A total of 4121 pregnant women had oral glucose tolerance test results (mean age, 28.8 years), 3746 of whom had glycemic trajectory data (mean age, 28.6 years); 983 women (23.8%) had gestational diabetes. 

"Monitoring the levels of blood sugar throughout pregnancy is important for assessing offspring growth patterns, particularly for pregnant women who did not receive a gestational diabetes diagnosis but who have hyperglycemia in late pregnancy because their offspring had significantly increased abdominal circumference (AC) after a gestational age of 34 weeks," wrote the authors.

Reference:

Zou J, Wei Q, Shi Y, Wang K, Zhang Y, Shi H. Longitudinal Associations Between Maternal Glucose Levels and Ultrasonographic Fetal Biometrics in a Shanghai Cohort. JAMA Netw Open. 2022;5(4):e226407. doi:10.1001/jamanetworkopen.2022.6407

KEYWORDS: JAMA, gestational diabetes, hyperglycemia, fetal growth, blood sugar, pregnancy, diabetes, gestational age, macrosomia, Jiao-jiao Zou, maternal glucose, blood glucose, offspring