Social Support / Canada / Prospective studies / Pregnancy / Humans / Placenta / Hair / Female / Adult / Paediatric / Public health systems and services research / Biological markers / Physiological Stress Markers / Preterm Birth / Case Control Studies / Socioeconomic Factors / Placenta / Hair / Female / Adult / Paediatric / Public health systems and services research / Biological markers / Physiological Stress Markers / Preterm Birth / Case Control Studies / Socioeconomic Factors