A coaching programme that included fathers slowed rapid infant weight gain in a trial
First Heroes enrolled 227 mother-father pairs and coached both through the first year. Infants in the programme were less likely to gain weight fast — but were no less likely to be overweight at one year.
A health-coaching programme that deliberately involved fathers, not just mothers, reduced the odds of rapid weight gain in infants during their first year, according to a randomised controlled trial published on 9 November in Pediatrics [s1]. The effect was real but partial: the programme moved the measure of how fast babies gained weight, yet did not change how many were overweight at 12 months.
Most early-life obesity prevention efforts focus on mothers. Fathers shape infant feeding, growth and family health habits too, but are rarely built into these programmes [s1]. The trial set out to test whether including them would help.
What the trial did
Researchers ran a randomised controlled trial from 2020 to 2023 within a Massachusetts health care system, enrolling 227 English- or Spanish-speaking mother-father pairs during the second trimester of pregnancy [s1]. Each pair was randomly assigned either to the intervention, called First Heroes, or to a control group that received safety education.
First Heroes consisted of three virtual health-coaching sessions plus multimedia content delivered from pregnancy through 12 months after birth [s1]. The pre-specified primary outcomes were the odds of rapid infant weight gain from birth to 6 months and from birth to 12 months, and whether the infant was overweight at 12 months. Secondary outcomes included mothers' postpartum weight retention, fathers' change in body mass index, and a range of parental health-care and infant-care behaviours [s1].
"Rapid weight gain" is a specific, well-established marker in infancy — a sharp upward crossing of growth percentiles that is associated with later obesity risk — rather than a judgement about any individual baby's size.
What it found
Among the 194 infants analysed, those in the intervention group had lower odds of rapid weight gain than controls at both time points [s1]. At 6 months the adjusted odds ratio was 0.42 (95% CI 0.19 to 0.93), and at 12 months it was 0.49 (95% CI 0.25 to 0.99) [s1]. Both intervals sit below 1, but the upper bounds are close to it — the result is statistically significant but not far from the line.
The other primary outcome did not move. There was no difference between the groups in the odds of an infant being overweight at 12 months [s1].
Among the adults, the signal was on the fathers' side. Fathers in the intervention group had a greater reduction in body mass index at 6 months postpartum than control fathers, an adjusted difference of −1.08 (95% CI −2.06 to −0.11) [s1]. Mothers' weight outcomes did not differ significantly between the groups [s1].
How to read it
The trial delivered a genuine but narrow result. On its own terms, First Heroes lowered the odds of the rapid-weight-gain marker, which is the outcome most tightly linked to later risk — and it did so while producing a measurable change in fathers' own weight, unusual for a programme of this kind. That is a meaningful proof of concept for including fathers.
But the headline has to carry the caveats. One of the two infant primary outcomes, overweight at 12 months, showed no effect, so the programme shifted the trajectory measure without shifting the status measure at one year [s1]. The confidence intervals on the weight-gain odds reach almost to no effect, the trial ran at a single health system, and 12 months is early — infancy weight patterns are not the same thing as childhood obesity. The authors themselves conclude that future work should look at how to sustain family-based prevention across infancy [s1].
What to watch
The open questions are durability and scale: whether a benefit visible in weight-gain trajectory at one year persists into the toddler years and beyond, and whether a brief, largely virtual, father-inclusive programme works outside one Massachusetts system. For context, see our coverage of childhood obesity and of what the evidence shows on early-life weight.
This article describes a single trial. It is not medical advice, and decisions about infant feeding and growth belong with a family's own clinicians.
Sources
- Father-Inclusive Perinatal Obesity Prevention: A Randomized Clinical Trial — Pediatrics , November 9, 2026
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