For decades, researchers and clinicians have focused on a mother’s contribution to child obesity, with study findings consistently highlighting significant drivers such as preconception overweight/obesity and gestational weight gain. But data have started to emerge demonstrating that an overlooked but equal driver: the father, whose genetics, habits, and environment shape child obesity risk from preconception to postconception and across adolescence in ways that many clinicians have never considered.

“For a long time, we’ve viewed birthing and early infancy as the primary role of the mother and have forgotten that dads might be contributing to overall child obesity risk,” said Matthew Landry, PhD, RDN, assistant professor and researcher at University of California-Irvine, and co-author of a review published this past May exploring the role of fathers in the intergenerational transmission of obesity.

John James Parker, MD, MS, Landry’s co-author, assistant professor at the Northwestern University Feinberg School of Medicine, attending physician in the Division of Advanced General Pediatrics and Primary Care at Ann & Robert H. Lurie Children’s Hospital of Chicago and an internist at Northwestern Medicine, Chicago, agreed.

“When I had kids, I was shocked to learn about the importance of transmissibility and that the genetic material I pass on changes based on my health status,” Parker told Medscape Medical News.

“As a doctor, I was lucky to learn this, even though I already had interest in this area (Parker’s research focus includes community, population health, and outcomes, especially paternal contributions). But I feel like every man should know whether or not they smoke, what they eat, and how much they sleep all factor into how healthy their child is going to be and what genes they are going to pass onto their child,” he said.

Intergenerational Obesity: The Fathers’ Role

Approximately 40%-79% of obesity is inheritable. Though there are more than 200 genes that are associated with obesity, epigenetic studies highlight that it is the interaction of certain obesity-related genes with environmental and societal factors that is responsible for the substantial increase in obesity observed in the US and globally.

Much of this starts in the preconception period — especially 3-6 months before conception — when sperm cells are especially sensitive to a variety of metabolic, inflammatory, endocrine, and environmental influences. These interactions affect sperm quality and quantity, lead to DNA fragmentation, and influence which genes are selected and then passed along through ejaculation and during fetal development.

This is where behavioral factors also come into play, as well as environmental influences (social determinants of health), all of which interact to shape how men approach their health and wellness before conception.

It is also where clinicians can start to have an impact.

“In my mind, the best approach might be more education at the preconception level about epigenetic factors,” said Pankaj Rajvanshi, MD, gastroenterologist and obesity medicine specialist, clinical assistant professor at the University of Washington, Seattle, and spokesperson for the Obesity Medicine Association.

“Genetic factors are influenced by the metabolic health of the male, their preconception weight, stress, tobacco use, alcohol use, etc. So if we are able to counsel men at this time to have better metabolic health, and address these other factors, those genes get turned off and transmission risk goes down,” said Rajvanshi.

Another important component is the impact of social determinants of health, said Natalie Muth, MD, MPH, MBA, RDN, pediatric medicine physician, registered dietician, obesity medicine specialist, and adjunct professor at the UCLA School of Public Health. Muth is also a spokesperson for the American Academy of Pediatrics.

“Whether it’s food security, housing, access to safe places for physical activity, adverse childhood events, we can’t lose sight of the fact that health is often beyond the full control of the individual person or family,” she said.

In the Clinic

Unlike most areas of clinical research, paternal influences on child health have often been overlooked and underrepresented in pediatric research. Rajvanshi said that now that the research linking sperm quality to obesity has emerged, there is an important opportunity to treat and manage the key paternal factors.

“I think that is why this review is so relevant because now, there is a recognition of multiple things that (will encourage) a refinement of our approach, ie, to treat everybody well in their own circumstances,” he said.

“There’s a role for all of us in this,” said Muth, adding she believed clinicians who are seeing men at the stage in their lives where they are having children have the opportunity to make one of the largest impacts.

Parker agreed.

“For men, especially young men, the obligation to their families is one of the most powerful motivating factors; they want to be healthy for their families,” said Parker.

“Describing the importance of their health on the health of their family is a way to motivate them to be healthy. It is a full family intervention and it’s important to have open communication between mothers and fathers so the entire family is making changes together,” he said.

Another strategy is to educate women directly, since they often make health decisions for their families.

“I don’t believe that a lot of women know that paternal health is equally important, so maybe clinicians and ob/gyns should start educating women during maternal or prenatal visits,” said Rajvanshi.

In their review, Landry and Parker wrote of the importance of including fathers in prenatal visits, which might yield adoption of healthy behaviors, support of maternal wellness, and engagement in early parenting.

Engaging in caregiving, whether it’s making dinner, establishing healthy eating habits, and physical activity also helps provide a roadmap for children, who research has shown, are highly influenced by paternal behaviors. The more the father is involved in modeling good behaviors increases the likelihood that children will pick up some of the same patterns.

Mental health is likewise important, said Rajvanshi. “Paternal depression has been shown to affect all aspects of childcare post-birth, eg, engagement, involvement, taking care of the kids, and this can be compounded by the lack of sleep,” he said. “A simple paternal test for depression and counseling could have a huge impact,” he said.

The role of fathers in shaping child obesity came as a surprise to Muth and Rajvanshi, both of whom are deeply involved in obesity management.

“You know, people who specialize in obesity medicine, like me, we haven’t really looked into this or considered this as much as we should,” said Muth.

“To be truly honest, when I read this paper, it changed me,” said Rajvanshi. “Moving forward, I’ll be adding this to the comprehensive assessment we already do,” he said.

Landry and Parker reported having no financial disclosures. Rajvanshi and Muth both reported being in private practice.

Liz Scherer is a US-based health/medical journalist who frequently covers obesity. She is a frequent contributor to Medscape US, Canadian, and Global-EU.