The Timing of In Utero Exposure
Shelley Ehrlich, MD, ScD, MPH, of the University of Cincinnati and Cincinnati Children’s Hospital Medical Center, is aiming, meanwhile, to learn how the timing of in utero exposure to hyperglycemia predicts specific metabolic and cardiovascular morbidities in the adult offspring of diabetic mothers.
“While we know that exposure to maternal diabetes, regardless of type, increases the risk of obesity, insulin resistance, diabetes, renal compromise, and cardiovascular disease in the offspring, there is little known about the level and timing of hyperglycemic exposure during fetal development that triggers these adverse outcomes,” said Dr. Ehrlich. A goal, she said, is to identify gestational profiles that predict phenotypes of offspring at risk for morbidity in later life.
She and other investigators with the TEAM (Transgenerational Effect on Adult Morbidity) study have recruited over 170 offspring of mothers who participated in the Diabetes in Pregnancy Program Project Grant (PPG) at the University of Cincinnati Medical Center from 1978 to 1995 — a landmark study that demonstrated the effect of strict glucose control in reducing major congenital malformations.
The women in the PPG study had frequent glucose monitoring (up to 6-8 times a day) throughout their pregnancies, and now, their recruited offspring, who are up to 43 years of age, are being assessed for obesity, diabetes/metabolic health, cardiovascular disease/cardiac and peripheral vascular structure and function, and other outcomes including those that may be amenable to secondary prevention (J Diabetes Res. Nov 1;2021:6590431).
Preliminary findings from over 170 offspring recruited between 2017 and 2022 suggest that in utero exposure to dysglycemia (as measured by standard deviations of glycohemoglobin) in the third trimester appears to increase the risk of morbid obesity in adulthood, while exposure to dysglycemia in the first trimester increases the risk of impaired glucose tolerance. The risk of B-cell dysfunction, meanwhile, appears to be linked to dysglycemia in the first and third trimesters — particularly the first — Dr. Ehrlich reported.
Cognitive outcomes in offspring have also been assessed and here it appears that dysglycemia in the third trimester is linked to worse scores on the Wechsler Abbreviated Scale of Intelligence (WASI-II), said Katherine Bowers, PhD, MPH, a TEAM study coinvestigator, also of Cincinnati Children’s Hospital Medical Center.
“We’ve already observed [an association between] diabetes in pregnancy and cognition in early childhood and through adolescence, but [the question has been] does this association persist into adulthood?” she said.
Preliminary analyses of 104 offspring show no statistically significant associations between maternal dysglycemia in the first or second trimesters and offspring cognition, but “consistent inverse associations between maternal glycohemoglobin in the third trimester across two [WASI-II] subscales and composite measures of cognition,” Dr. Bowers said.
Their analysis adjusted for a variety of factors, including maternal age, prepregnancy and first trimester BMI, race, family history of diabetes, and diabetes severity/macrovascular complications.
Back In The Laboratory
At the other end of the research spectrum, basic research scientists are also investigating the mechanisms and sequelae of in utero hyperglycemia and other injuries, including congenital malformations, placental adaptive responses and fetal programming. Researchers are asking, for instance, what does placental metabolic reprogramming entail? What role do placental extracellular vesicles play in GDM? Can we alter the in utero environment and thus improve the short and long-term fetal/infant outcomes?
Animal research done at the UMSOM Center for Birth Defects Research, led by Dr. Reece and Peixin Yang, PhD, suggests that “a good portion of in utero injury is due to epigenetics,” Dr. Reece said in the interview. “We’ve shown that under conditions of hyperglycemia, for example, genetic regulation and genetic function can be altered.”
Through in vivo research, they have also shown that antioxidants or membrane stabilizers such as arachidonic acid or myo-inositol, or experimental inhibitors to certain pro-apoptotic intermediates, can individually or collectively result in reduced malformations. “It is highly likely that understanding the biological impact of various altered in utero environments, and then modifying or reversing those environments, will result in short and long-term outcome improvements similar to those shown with congenital malformations,” Dr. Reece said.