U.K. Moms are Turning Parenting into an Experiment.

In one Parenting Science Gang study, sensors measure temperature variations when a baby is carried by an adult doing light exercise.

On 21 February, about 160 lactating mothers will head to Charing Cross Hospital in London to donate 25 milliliters of milk each for an unusual scientific study. The freshly pumped samples will be analyzed to determine how the composition of human milk changes with the nursling's age, from 3 months to 4 years old.

It's a matter about which surprisingly little is known. But the experiment is equally remarkable for its origin: A group of mothers came up with the idea for the study and designed it together with breast cancer researcher Natalie Shenker and microbial ecologist Simon Cameron, both at Imperial College London. The mothers recruited the milk donors—in just a few days—and they will be involved in the data analysis and possible write-ups.

This unusual collaboration was made possible by the Parenting Science Gang (PSG), a citizen science project in the United Kingdom funded by the Wellcome Trust. It links parents, gathered in Facebook groups around a specific interest, with scientists who help them design and carry out experiments. The project, which has already initiated multiple lines of research into issues such as schooling and gender stereotypes, is an effort to bring evidence to a realm rife with uncertainty and folk wisdom. "I try to raise my children with science in mind," explains Melissa Branzburg, a PSG member and mother of two.

Several blogs and publications have recently sprung up to address the growing hunger for evidence among science-minded parents, and some academics are dispensing advice as well. But PSG allows parents to take matters into their own hands. It was born from a smaller-scale project in which mothers studied which detergents were best to clean cloth diapers, or nappies. ("There are no scientists looking at washable nappies," says PSG Founder and Director Sophia Collins.) The Nappy Science Gang ran from March to November 2015, with funding from the Wellcome Trust and the United Kingdom's Royal Society of Chemistry; it showed there was no evidence that "nonbiological" detergents—which lack dirt-attacking enzymes—help avoid skin irritation. The finding led the United Kingdom's National Health Service to rescind its recommendations to use them.

After the project ended, the trust donated £147,000 to launch PSG, which started in February 2017 and will run for 2 years. Some 2000 parents are involved, the vast majority of them women, despite efforts to include fathers. PSG addresses issues that matter to mothers, whereas funding agency committees "are often made up of middle-aged white men who have a different perspective," Collins says. "As a parent, our point of view is being taken seriously," says PSG member Mitch Wright, a mother of one. "It makes me feel empowered."

The mothers behind the milk study want to know how human milk changes after children reach age 2. Mothers are often told there is no benefit to breastfeeding past a certain age, even though many children around the world wean between 2.5 and 7 years old. The study will also act as a pilot project to plan recruitment for a large study on the links between breast cancer risk and infant feeding, and it could benefit an area that Shenker is interested in as co-founder of the Hearts Milk Bank, based at the University of Hertfordshire in the United Kingdom, which provides donated milk to babies in neonatal units and for research purposes. At the moment, donors are recruited in the first 6 months of their baby's life and can donate until the infant reaches age 1. Yet Shenker says that preliminary evidence from other studies suggests that as a baby goes into toddlerhood, milk becomes higher-calorie and richer in antimicrobials. "Would that be more appropriate for a preterm baby? This could make a big difference. We don't know."

PSG members have plenty of other questions. One subgroup teamed up with environmental physiologist Davide Filingeri, head of the Thermosenselab at Loughborough University in the United Kingdom, to help answer a question that vexes many new parents: How many layers of clothing are needed to keep babies carried in a sling comfortable while avoiding overheating? There is "surprisingly little evidence" behind oft-repeated advice to give a baby "one extra layer of clothing" beyond what an adult would wear, Filingeri says. His role was to help translate the mothers' idea into a robust experimental design to measure babies' temperature variations in different conditions. The study, which is ongoing, will include about 15 mother-baby pairs.

A third PSG study focuses on flexi-schooling, an arrangement in which children are registered at school but attend part-time, for instance because their parents think they need additional support or to accommodate a special interest in art. The mothers will conduct a survey of parents of flexi-schooled children, as well as interviews with teachers, and will use Freedom of Information Act requests to learn the numbers of flexi-schooling requests and refusals in Scotland. Other, more recent PSG subgroups will focus on gender stereotypes, health care experiences around breastfeeding, as well as pregnancy and birth for women with a higher body mass index.

Wright says PSG has so inspired her that she wants to study chemistry or forensic science. But the goal is not to turn every parent into a scientist, Collins says; nor does she expect all participants to become experts at reading scientific literature. "But they might become more critical of what they read; they might seek information from a science magazine [or a clinical body] instead of a celebrity blog."

The studies are also an opportunity for parents to learn more about the process of science. In the milk study, for instance, the mothers had to understand the practical limitations of mass spectrometry, the technique used for analyzing the milk. "They had hoped to analyze a wider range of compounds in milk, such as antibodies," Cameron says. Filingeri says he insisted on keeping the temperature study's scope as specific as possible, explaining to the mothers that "it's more beneficial to focus on one question or one set of small questions." Tara Jones, an education researcher at the University of West Scotland in Paisley who provides guidance to the flexi-schooling group, encouraged the mothers to question their preconceptions and remain objective. "They'd made certain assumptions that flexi-schooling was a good thing," she says.

Carlos González, a pediatrician in Gavá, Spain, who wrote several parenting books peppered with peer-reviewed references, applauds the initiative—and yet he cautions that parenting often isn't about evidence, but about choices. "Science cannot tell us how to raise our children," González says. "Science can offer data that we can use to make decisions, but it cannot decide for us, because we have beliefs, principles, desires, and goals."