Poster Presentation International Association of the Diabetes and Pregnancy Study Groups 2022 - Hosted by ADIPS

Circulating beta-hydroxybutyrate levels in overweight and obese pregnant women at 28 weeks gestation are not associated with dietary carbohydrate (#83)

Helen Tanner 1 , Hui Ting Ng 2 , Grace Murphy 2 , Leonie K Callaway 1 , David McIntyre 3 , Helen L Barrett 4 5 , Marloes Dekker Nitert 2
  1. Obstetric Medicine, Royal Brisbane and Women's Hospital, Brisbane, QLD
  2. School of Chemistry and Molecular Biosciences, The University of QLD, St Lucia, QLD
  3. Obstetric Medicine, Mater Health, South Brisbane, QLD
  4. Mater Research Institute- The University of QLD, South Brisbane, QLD
  5. Obstetric Medicine, Royal Hospital for Women, Randwick, NSW

Background: Late pregnancy is associated with an accelerated starvation response, with increased production of ketone bodies including beta-hydroxybutyrate (B-OHB) from stored lipids. Normal B-OHB levels are considered to be less than 0.5 mmol/L. Maternal serum ketone levels ranging from 0.05 – 0.25 mmol/L have been found to be inversely associated with childhood IQ. However studies have found conflicting results.  Current dietary guidelines advise pregnant women to consume 175g of carbohydrates daily to prevent ketogenesis. The aim of this study was to analyse the relationship between dietary carbohydrate intake and circulating B-OHB levels at 28 weeks gestation.

Methods: B-OHB levels were measured by Liquid Chromatography-Mass Spectrometry in fasting blood samples of 107 overweight and obese participants in the SPRING (Study of PRobiotics IN Gestational diabetes) trial with carbohydrate intakes between 73 and 374 g/d as assessed by food frequency questionnaire at 28 weeks gestation. Differences in B-OHB levels were evaluated by Mann-Whitney U tests given that the data was not normally distributed. B-OHB levels were correlated with carbohydrate and other macronutrient intake, biochemical markers, OGTT levels and clinical characteristics.

Results: The median circulating B-OHB level was 0.062 mmol/L (IQR 0.038 – 0.098, range 0.0001-0.297 mmol/L) . Circulating B-OHB levels did not correlate with carbohydrate intake (Spearman’s rho = 0.14, P= 0.16) nor intake of any other macronutrient, maternal BMI, age, gestational weight gain, infant birthweight or infant length. The 1-hour OGTT blood glucose level was the only biochemical marker that was marginally correlated with B-OHB levels (rho 0.19, P = 0.056). When comparing women with B-OHB levels below and above the median of 0.062mmol/L, the only marginal difference was in 1-hour OGTT blood glucose level (below median B-OHB: 6.7 mM vs. above median B-OHB: 7.3 mM, P = 0.085).

Conclusion: Detectable circulating B-OHB levels were present in all participants and within the range associated with reduced childhood IQ. Carbohydrate intake at 28 weeks gestation does not affect circulating B-OHB levels in overweight and obese pregnant women. The higher 1-hour OGTT glucose values in women with higher fasting B-OHB concentrations could reflect a lower carbohydrate intake in the 24 hours before the OGTT, which was not recorded in this study. In summary, low levels of circulating B-OHB are common in late pregnancy and are not associated with routine dietary macronutrient intake.