The international community has given insufficient attention to the social, health and economic needs of adolescents before they are parents

A child’s growth and development is affected by the health and lifestyles of their parents before pregnancy – even going back to adolescence – according to a new study by researchers at the Murdoch Children’s Research Institute, the University of Melbourne, and Columbia University’s Mailman School of Public Health. The findings show that tackling obesity, mental health, poor nutrition and substance abuse in young people before they become parents is essential for the best possible start to life for their future children. The results are published online in the journal Nature.

Taking action once a woman knows she is pregnant is often starting too late, according to the researchers. Young women and men often carry lifestyle and health risks from adolescence into pregnancy, they added, even if this happens in their 20s or 30s.

Using data from 200 countries and more than 140 recent research papers, the researchers considered mechanisms other than genes for how health and growth was transmitted between generations, including changes in a father’s sperm or a mother’s ovum, maternal influences around the time of conception and in later pregnancy, and parenting in the first two years after birth. In high- and middle-income countries, the paper highlighted three main areas for action in adolescence: mental health, obesity and substance abuse.

“The first 1000 days of a child’s life are crucially important, but that is too late to be taking action. Current policies to promote the best possible start to life in most countries are starting too late,” said George Patton of the Murdoch Children’s Research Institute, and lead author.

“The health system now only kicks into action with a woman’s first antenatal visit, most often eight to 14 weeks into a pregnancy. We need the health service system to be engaged before pregnancy – and it should go beyond its current focus on contraception to tackle broader health risks and emotional well-being in both young women and men,” said Patton.

There is a rapid increase in obesity across adolescence and young adulthood, according to the authors. Maternal obesity during pregnancy predicts later childhood obesity, poorer cognitive skills and greater childhood behavioural problems.

Smoking, alcohol and drug use rise steeply in adolescence, and the researchers found consistent and clear evidence that persisting maternal tobacco, alcohol, cannabis and other illicit drug use in pregnancy adversely affects offspring growth and development. Stopping use when a woman recognizes she is pregnant may be too late to address the early effects on a baby.

“Global adolescent fertility also remains a major health challenge, both for the children and for the adolescents, noted Vegard Skirbekk, PhD, of the Columbia Aging Center, professor of Population and Family Health at Columbia’s Mailman School of Public Health, and study co-author. “High levels of teenage fertility may worsen social, economic and health outcomes both among adults and among the children in the next generation.”

For many lower-income countries, the paper recommended major actions around ending child marriage, delaying first pregnancy through contraception and girls staying in school, and tackling under-nutrition.

The authors also questioned the age range of adolescence. Current research suggests that physical and neurological growth continues into the 20s. The paper said this, combined with social changes such as the later adoption of adult roles, meant adolescence was better considered to range between 10 and 24.

“We need health services to go beyond a traditional focus on reproductive health, to a more comprehensive and integrated engagement with adolescent and young adult health,” according to Patton.

Creating health-promoting environments in the families, schools, workplaces and communities where this generation of young adults is growing up is critical, noted the authors, and will make a huge difference for themselves and for their children.