Associations between maternal diet, lifestyle and sociodemographic factors with placental and offspring outcomes

According to the Developmental Origins of Health and Disease (DOHaD) hypothesis, early intrauterine exposures, such as maternal nutrition and lifestyle, can have lasting impacts on offspring health from infancy through adulthood. Placental weight (PW) and the birthweight:placental weight (BW:PW) ratio, which are indicators of placental growth and efficiency, are understudied in this context but may play a critical role in influencing offspring health trajectories. The role of maternal diet, lifestyle, and socioeconomic status (SES) in shaping these placental outcomes, and the potential for sex-specific differences, remains relatively unknown. Addressing these gaps, the overarching aim of this thesis is to examine the associations of maternal diet, lifestyle, and SES with placental outcomes and their relationship with offspring health. Additionally, this work explores whether these associations differ by the sex of the offspring. This study utilises secondary data from two Irish birth cohorts: the Lifeways Cross-Generation cohort, representing the general population, and the PEARS cohort, focusing on a group of mothers with overweight or obesity. Chapter 3 investigated maternal diet in the Lifeways cohort using multiple linear regression. Pro-inflammatory and high glycaemic index diets were positively, and high diet quality scores were negatively, associated with PW. Sex-specific effects showed female foetuses more sensitive to maternal glucose levels and male foetuses to inflammatory diets. This aligns with Chapter 6 findings in PEARS mothers without pregnancy complications, whereby a more pro-inflammatory diet was associated with increased placental weight and lower placental efficiency in male offspring. In Chapter 4, maternal physical activity and alcohol intake, but not a composite healthy lifestyle score, influenced placental development in a sex-specific manner. For example, low maternal physical activity was consistently associated with a lower BW:PW ratio at extreme centiles, particularly in female offspring. Chapter 5 explored the role of SES. In Lifeways, cluster analysis identified "Renters" as having adverse outcomes, including lower BW and poorer dietary quality. PLS regression highlighted nulliparity as a significant predictor of lower PW and BW in both cohorts. Finally, Chapter 7 examined the long-term influence of placental outcomes on offspring body mass index (BMI) trajectories. Results from linear mixed-effects models showed that PW was positively associated with offspring BMI in a non-sex specific manner, but this effect diminished by age nine. The results of this thesis provide novel insights into how maternal diet, lifestyle, and sociodemographic factors influence placental development and long-term offspring BMI. Diet and lifestyle interventions during early pregnancy hold the potential to significantly optimise maternal and foetal health. To better understand these associations, future longitudinal research is warranted, particularly in larger and more diverse populations.