Where do most stars (and the planetary systems that surround them) in the Milky Way form? What determines whether a young star cluster remains bound (such as an open or globular cluster), or disperses to join the field stars in the disc of the Galaxy? These questions not only impact understanding of the origins of stars and planetary systems like our own (and the potential for life to emerge that they represent), but also galaxy formation and evolution, and ultimately the story of star formation over cosmic time in the Universe. This volume will help readers understand our current views concerning the answers to these questions as well as frame new questions that will be answered by the European Space Agency's Gaia satellite that was launched in late 2013. The book contains the elaborated notes of lectures given at the 42nd Saas-Fee Advanced Course "Dynamics of Young Star Clusters & Associations" by Cathie Clarke (University of Cambridge) who presents the theory of star formation and dynamical evolution of stellar systems, Robert Mathieu (University of Wisconsin) who discusses the kinematics of star clusters and associations, and I. Neill Reid (S pace Telescope Science Institute) who provides an overview of the stellar populations in the Milky Way and speculates on from whence came the Sun. As part of the Saas-Fee Advanced Course Series, the book offers an in-depth introduction to the field serving as a starting point for Ph.D. research and as a reference work for professional astrophysicists.

The issues explored in this book have unfortunately come to be known as 'maternal-fetal conflicts'. The phrase is unsatisfactory because it is misleading: It places the emphasis on the well-being of the fetus instead of on the born child (who will bear the burden of any harm done prenatally); it assumes a conflict between a pregnant women and her offspring (while the issue is usually more complex and more broadly based); and it incorrectly implies that all pregnant women are appropriately regarded as mothers. For these reasons, I have chosen to avoid the phrase 'matern- fetal conflict' altogether, and will instead speak in terms of 'preventable prenatal harm'. I mention this at the outset, for those of you familiar with 'maternal-fetal conflicts' who might be wondering if I am addressing the same issues. Yes. But I am trying to look at them in a new - and I hope more fruitful - way. I would like to thank the other participants in the Hastings Center's maternal-fetal project - especially those who disageed with me - for being so thought-provoking. And I owe a lasting debt of gratitude to Henry Ruth and Allen Buchanan for their invaluable counsel.

The issues explored in this book have unfortunately come to be known as 'maternal-fetal conflicts'. The phrase is unsatisfactory because it is misleading: It places the emphasis on the well-being of the fetus instead of on the born child (who will bear the burden of any harm done prenatally); it assumes a conflict between a pregnant women and her offspring (while the issue is usually more complex and more broadly based); and it incorrectly implies that all pregnant women are appropriately regarded as mothers. For these reasons, I have chosen to avoid the phrase 'matern- fetal conflict' altogether, and will instead speak in terms of 'preventable prenatal harm'. I mention this at the outset, for those of you familiar with 'maternal-fetal conflicts' who might be wondering if I am addressing the same issues. Yes. But I am trying to look at them in a new - and I hope more fruitful - way. I would like to thank the other participants in the Hastings Center's maternal-fetal project - especially those who disageed with me - for being so thought-provoking. And I owe a lasting debt of gratitude to Henry Ruth and Allen Buchanan for their invaluable counsel.

Where do most stars (and the planetary systems that surround them) in the Milky Way form? What determines whether a young star cluster remains bound (such as an open or globular cluster), or disperses to join the field stars in the disc of the Galaxy? These questions not only impact understanding of the origins of stars and planetary systems like our own (and the potential for life to emerge that they represent), but also galaxy formation and evolution, and ultimately the story of star formation over cosmic time in the Universe. This volume will help readers understand our current views concerning the answers to these questions as well as frame new questions that will be answered by the European Space Agency's Gaia satellite that was launched in late 2013. The book contains the elaborated notes of lectures given at the 42nd Saas-Fee Advanced Course "Dynamics of Young Star Clusters & Associations" by Cathie Clarke (University of Cambridge) who presents the theory of star formation and dynamical evolution of stellar systems, Robert Mathieu (University of Wisconsin) who discusses the kinematics of star clusters and associations, and I. Neill Reid (S pace Telescope Science Institute) who provides an overview of the stellar populations in the Milky Way and speculates on from whence came the Sun. As part of the Saas-Fee Advanced Course Series, the book offers an in-depth introduction to the field serving as a starting point for Ph.D. research and as a reference work for professional astrophysicists.