Yogurt intake before pregnancy is associated with improved maternal mental health at 24 weeks postpartum

Introduction:
Dairy foods are a major source of important nutrients including protein, calcium and various vitamins, which are essential for proper infant and child development. Increasing dairy intake has been a prominent dietary recommendation for most pregnant and lactating Canadian women. However, recommendations for the consumption of dairy is largely absent from the new Canadian Food Guide. The objective of this project was to determine the relationship between dairy product intake by women before, during and after pregnancy and key maternal, infant and child health outcomes.

Methods:
The APrON study, a prospective cohort project which gathered dietary and biological data from nearly 2200 pregnant women, was conducted at local clinics and hospitals in Edmonton and Calgary starting in 2009. Nutritional and developmental data was also collected from the infants and children of women who participated in APrON. Dietary, anthropometric and mental health data from mothers and anthropometric and developmental data from infants and children were analyzed. Maternal total and individual dairy product intakes were quantified with a food frequency questionnaire before pregnancy and 24-hour dietary recalls, which were conducted during each trimester and at 3 months postpartum. A serving of milk, yogurt and cheese was equal to 1 cup, ¾ cup and 50 g, respectively. The presence of pregnancy and non-pregnancy related complications were summed and compiled into a total score for each maternal participant. Child neurodevelopment was estimated using emotional control and attentional problems scores from the Behaviour Rating Inventory of Executive Function Preschool (BRIEF-P) and Child Behaviour Checklist (CBCL) questionnaires, respectively. Multivariate regression models were developed when controlled for potential confounders.

Results:
The average maternal intake of dairy significantly increased across pregnancy (the mean and standard deviation of intake in the first (n= 291) versus third trimester (n= 927) was 2.31 servings/day ± 1.49 and 2.81 servings/day ± 1.70, respectively; p<0.001). There were no significant relationships between milk, yogurt, cheese or total dairy intakes and gestational weight gain, maternal complication scores, infant birth weight, length and head circumference, and child neurodevelopment scores at 2 and 3 years of age. However, women who reported consuming more servings of yogurt before they became pregnant (x̄= 0.14 servings/day) had a significantly lower Edinburgh Postnatal Depression Scale (EPDS) score at 24 weeks postpartum (p= 0.009), where a lower score indicates that a woman has less symptoms consistent with postpartum depression. There was also a trend towards this relationship at 12 weeks postpartum (p= 0.055). Conclusion: The results suggest that an increased yogurt intake before pregnancy is associated with lower EPDS scores at 24 weeks postpartum. Results also suggest that milk and dairy intake throughout gestation and postpartum are not significantly associated with any negative maternal, infant or child health outcomes for the variables measured. Milk and dairy products may provide significant health benefits and their consumption before, during and after pregnancy should not be discouraged.