Providing the healthiest and safest environment in the first 1,000 days of life is the greatest gift which parents can give to their children. We return to the theme of control over our lives to ask who is in control of this gift, and whether today’s medicine and public health hold the answers. We explore the dilemmas facing today’s governments and the decisions that individuals make in terms of personal responsibility when maternal and child health are not prioritised by health policy-makers. We discuss sexual and reproductive rights, why women’s health has not been prioritised – especially during the pandemic – and reasons for high maternal mortality in some countries. We offer an optimistic close to the book; a call to action. We explain that, while planning for parenthood is important, the actions needed do not have to be sustained over a long period. We emphasise the many opportunities which adolescents and young people can seize as the parents of the future. This hope can generate the resolve to make the first 1,000 days of life as good as possible for the next generation. Knowing the secrets of our first 1,000 days is a vital part of this.

Why is birth so dangerous, even today, with modern medicine? Through historical anecdote and a contemporary case history we explore this question, discussing the process of birth and what can go wrong. By thinking about who is in control of labour – is it the mother or her fetus? – we think about how a couple might prepare for birth. The challenge posed by birth makes us look to human evolution for answers, and we describe the insight it gives into birth in some low-resource settings around the world. We tackle the question of the rising numbers of caesarean sections around the world and the possible consequences. Although it may be widely believed that a smaller baby would mean a less difficult birth, we go on to explore the risks of being small for the survival of the baby alongside new research revealing how the mother’s body limits the growth of her baby inside the womb. We discuss whether the growth of the fetus is set by the genes which the mother or the father have passed on, mother’s size, or her environment. This leads to how the fetus develops and what controls this, the focus of the next chapter.

Here we uncover the mysteries of the baby as it develops in the womb, discussing how fetal development is controlled. We give insights into aspects of pregnancy not widely known, from the fetus starting to breathe months before it is born, to the question of whether it sleeps – and dreams. We discuss the ways in which information about the mother’s life and her environment affect the baby’s development. Although birth may seem the first major milestone for a baby, we emphasise that many other milestones have been passed before that, inside the womb, out of sight but over which parents can have substantial influence. We give insights into new discoveries about how the organs of the fetal body develop in prediction of the world in which that individual ‘expects’ to live, and what happens when the prediction turns out to be wrong. The idea that the fetus is preparing for life after birth will get the reader thinking about the long-term consequences of the way a fetus develops. Each of us is unique as a result of our development – and nobody is perfect. Our unique development starts from the moment of conception, which introduces the next chapter on sex.

None of us can really remember anything about our lives before the age of two years. How much of what makes us what we are has been set by that time? We challenge the widely-accepted idea that what we are is ‘determined’ by inherited genes and we start to explore how interaction with parents/carers establishes our behaviour. We use examples drawn from fiction and the real world to explore how the brain learns from the conditions in early life. We explain why this adaptability underpins development of our senses, our behaviour and our self-control. This introduces control as one of the themes of the book – how much we are in control of our bodies and how control develops based on environmental cues. We question what effect today’s exposure to digital media may have on the developing brain, and explore new ideas about the development of defence mechanisms, from immunity to the gut microbiome. Through the quote from JM Barrie, author of ‘Peter Pan’: ‘You always know after you are two. Two is the beginning of the end’, we ask whether age two is the beginning of the end or the end of the beginning of development.

We provide food for thought on some pressing questions about health inequalities – why some of us maintain good health into old age, and the inequity of infectious and Non-Communicable Diseases, both very relevant now to COVID-19. We use historical perspectives and modern examples to discuss the population explosion, social determinants of health and how development over the first 1,000 days influences later health. Some ideas are likely to be quite novel to the reader, such as the risk of disease being increased by ‘mismatch’ between our developmental environment and where and how we live later. This takes the story across the globe, from high- to low-income countries, where early development is often less healthy but economic progress is changing environments fast. Can young people in such settings escape, or has the anvil on which their bodies were forged in early life left them with unalterable inequalities? We ask who needs to ‘own’ these problems and why solutions to them have been slow to emerge. The wider, global perspective, sets the scene for the final chapter which focuses on what we can all do as individuals now that we know some of the secrets of our first 1,000 days.

Sex. We walk the reader through why it matters to generate variation in a species. The mixing of genes from two sexes will be familiar to most readers as the reason for the uniqueness of each of us, right from the moment of conception. But we give insight on the other, less widely understood, ways that the differences between us come about. This leads to explanation of the early ‘conversations’ between the mother and her embryo that take place, and why they matter. We give some current and long-standing examples of mankind’s attempts to control conception or to encourage it, including the eugenic sterilisation agenda, artificial insemination and pregnancy termination after fetal sex determination. We explore one of the most hotly debated areas of medicine, assisted reproductive technologies, to which many people will relate. We encourage the reader to challenge the way they think about the preconception period, and consider why the responsibility seems to fall on girls and women, with its consequences for gender equality. This leads to the next chapter.

There is a worldwide epidemic of non-communicable diseases (NCDs), including cardiovascular disease (CVD), type 2 diabetes, chronic lung disease, and some forms of cancer; predisposition to these is linked to obesity. This is despite efforts by individuals to modify their diet and lifestyle, and government and global programs aimed at promoting healthy eating or increased physical activity. Some initiatives have begun to target childhood eating and activity. But a strong and international body of scientific and epidemiological data suggests that health interventions should be focused on a much earlier period of development: pregnancy. Expectant couples are often focused on the immediate result of their pregnancy – a viable baby. It may come as a surprise to many of them to hear that the finer details of building a baby are in fact the foundation of lifelong health.