An estimated 8 million tonnes of plastic enter our oceans each year. But the plastic we find in our surface waters is more than 100-fold lower. This is the 'missing plastic' problem.

Maternal mortality was much more common in the past. Today, it is much lower — but there are still large inequalities across the world.

The world needs ideas and innovation to make progress. Creative and talented people are everywhere, but the opportunity to develop is limited to only a small number of well-off children. The world loses out as a result.

Social media sites are used by more than two-thirds of Internet users. How has social media grown over time?

Pregnancy and childbirth are much safer for women today than in the past. But maternal mortality rates are still high in many countries in the world. A woman is 300 to 400 times more likely to die per pregnancy in poor countries than in rich.

For most of our history, pregnancy and childbirth were dangerous for both baby and mother. Whilst maternal mortality has decreased significantly in recent decades, more than 300,000 women die from pregnancy every year.

Growing demand for seafood has placed increasing pressures on wild fish populations. One innovation has helped to alleviate some of the pressure on wild fish catch: aquaculture, the practice of fish and seafood farming. Aquaculture production has now overtaken wild fish catch.

The death of a young child has always been the most devastating tragedy mothers and fathers could experience. How common was it?

Social media platforms like Facebook reach one-in-three people in the world. What does the research tell us about the causal impact of social media use on our well-being?

Our understanding of the world is often shaped by geographical maps. But this tells us nothing about where in the world people live. To understand this, we need to look at population density. How does population density vary across the world?

In the past the average woman had five children. In the past fifty years, this number has halved as a result of women empowerment, declining child mortality and the rising cost of bringing up children.

Nearly one-in-four adults in the world smokes tobacco. More than one-third of men, but just over 8% of women do. How do sex differences in smoking vary across the world?

One-in-five (20%) of adults in the world smoke tobacco. But where in the world is smoking most common?

Today’s global inequality of opportunity means that the good or bad luck of where you were born matters most for your living conditions. We look at how this chance factor is the strongest determinant of your standard of living, whether in life expectancy, income, or education.

The world has made significant progress in recent decades in reducing deaths from diarrheal diseases, particularly for children. One of the most successful interventions has been oral rehydration therapy (ORT): a simple salt, water and sugar solution. We look at what ORT is, how it was developed, and how many lives it might have saved.

Rotavirus is the leading cause of diarrheal deaths in children. There is, however, an effective tool against it: the rotavirus vaccine.

Despite being treatable and preventable, 1.6 million people died from diarrheal diseases in 2017; one-third were children under five years old. This makes it one of the largest killers of children. Here we look at where and why children are dying from diarrheal diseases, and what we can do to stop this.

15,000 children under five years old die every day. To reduce this figure we need to understand what children are dying from, and what interventions are available to stop this. Here we look at the number of children dying by each cause – from pneumonia to diarrheal diseases, malaria and malnutrition. We also present the range of interventions that are available to prevent children from dying.

How does sex ratio at birth vary across the world? We might expect that naturally an equal number of boys and girls are born, but this is not the case. There are biological reasons why more boys than girls are born each year: around 105 boys per 100 girls. But in countries with a strong son preference, the sex ratio is even more skewed.

Here we look at results from the largest global survey to date – the Wellcome Global Monitor – on attitudes to vaccination across the world.

What effect do public attitudes have on vaccine coverage rates, and what can we do about skepticism to vaccines?