Longitudinal circulating concentrations of long‐chain polyunsaturated fatty acids in the third trimester of pregnancy in gestational diabetes

Gestational diabetes mellitus is a common complication of pregnancy. Long‐chain polyunsaturated fatty acids (LCPUFA) are essential for fetal neurodevelopment. Docosahexaenoic acid (DHA) is the predominant n–3 LCPUFA in the brain and retina. Circulating absolute concentrations of total n–3 and n–6 LCPUFAs rise during normal pregnancy. It remains unclear whether gestational diabetes may affect the normal rise in circulating concentrations of LCPUFAs in the third trimester of pregnancy – a period of rapid fetal neurodevelopment. This study aimed to address this question.

In a prospective singleton pregnancy cohort, fatty acids in fasting plasma total lipids were measured at 24–28 and 32–35 weeks of gestation in women with (n = 24) and without gestational diabetes mellitus (n = 116). Fatty acid desaturase activity indices were estimated by relevant product‐to‐precursor fatty acid ratios. Dietary nutrient intakes were estimated by a food frequency questionnaire.

Plasma absolute concentrations of total n–6 LCPUFAs rose significantly between 24–28 and 32–35 weeks of gestation in women with or without gestational diabetes, whereas total n–3 LCPUFAs and DHA concentrations rose significantly only in women without gestational diabetes (all P < 0.01). Delta–5 desaturase indices (20:4n–6/20:3n–6) were similar, but delta–6 desaturase indices (18:3n–6/18:2n–6) were significantly lower in women with gestational diabetes at 32–35 weeks of gestation. Dietary intakes of all fatty acids were comparable.

The normal rise in circulating absolute concentrations of DHA and total n–3 LCPUFAs in the third trimester of pregnancy may be compromised in gestational diabetes, probably due to impaired synthesis or mobilization rather than dietary intake difference.