Excess insulin resistance in pregnancy is associated with offspring adiposity and cardiometabolic risk. Diet and stress are known to influence glycemic control, however, their combined effects have not been studied in the context of pregnancy. The aim of this study is to test the main and interaction effects of maternal Mediterranean diet adherence and stress (negative mood) across pregnancy on insulin resistance (Homeostasis Model of Assessment of Insulin Resistance (HOMA-IR)).


In a prospective study of N=203 healthy pregnant women, data were collected at 3 time points across gestation for assessment of: i) Diet: 3 x 24h-diet recalls per time point, from which the Mediterranean Diet Score (MDS) was derived; ii) Negative Mood: Ecological Momentary Assessment was performed in ambulatory settings using an electronic diary, with multiple daily entries over 4 days at each time point, from which a mean composite Negative Mood Score (NMS) was derived; iii) HOMA-IR: computed from fasting plasma glucose and insulin measurements at each time point. Generalized Estimating Equations were used to test the main effects of repeated measures of MDS and NMS on HOMA-IR across pregnancy, as well as the effects of their interaction with time point of assessment (MDS*NMS*time), adjusting for key covariates (age, pre-pregnancy BMI, socioeconomic status, ethnicity).


There was no significant main effect of MDS on HOMA-IR (B=-0.011, p=0.539). NMS was positively associated with HOMA-IR, independent of diet and stage of pregnancy (B=0.175, p=0.039). The interaction term MDS*NMS*time was significantly associated with HOMA-IR (B=0.188, p=0.048), such that poor adherence to the Mediterranean diet in late pregnancy exacerbated the effects of a high NMS on insulin resistance, compared to the combined effects in early pregnancy.


Maternal negative mood may influence insulin resistance across pregnancy. In late pregnancy, this effect may be moderated by a poor quality Mediterranean-type diet.