Childhood Obesity & Fertility: What the Evidence Shows
If you’ve carried worry about how your past health might affect your fertility, you’re not alone. A long‑term study, published in Fertility & Sterility (2018), explored whether childhood obesity before age 12 may raise the risk of infertility in adulthood.
Key Findings
This study followed 1,544 Australian girls, starting between the ages of 7–15, and tracked their health and fertility into adulthood.
Girls who were living in larger bodies between ages 7 and 11 were nearly three times more likely to experience infertility later in life, compared to girls in mid-sized bodies.
They were also almost four times more likely to report trying to get pregnant for over a year without success, which is a common medical definition of infertility.
Interestingly, the researchers found a “U-shaped” pattern: children who were either underweight or overweight in that younger age window faced higher fertility struggles later on.
Weight gain that began in adolescence (ages 12–15) didn’t show the same link. This suggests that early childhood may be a particularly sensitive window for reproductive development.
Why This Matters
This study helps expand our understanding of how early-life health patterns may influence reproductive outcomes in adulthood and adds to a growing conversation about how fertility is shaped across the lifespan, not just in the moment someone decides to conceive.
That said, it’s important to approach these findings without blame. Body size in childhood is influenced by a complex mix of genetics, environment, food access, family systems, and movement — all of which are shaped by broader social and economic factors, not individual choices.
This research doesn’t suggest that higher weight causes infertility. It only shows an association that calls for more investigation. Fertility is multifaceted, and this is just one piece of a larger picture that includes hormones, inflammation, metabolism, stress, medical history, and more.
It’s also worth noting the limitations of this study:
The participants were all from Australia and predominantly white, which may limit how broadly the findings apply across cultures or ethnicities.
Body size was measured only at two time points in childhood and adolescence, so we don’t know how ongoing changes or patterns might play a role.
And while the study tracked self-reported infertility, it didn’t include clinical diagnoses or explore other contributing health factors like PCOS, endometriosis, or sperm-related infertility.
Ultimately, this research can offer helpful insights, but it doesn’t predict any one person’s fertility future. What it does remind us is that reproductive health is connected to the whole-body experience over time and that early prevention, access to nourishing care, and body-neutral support from providers can all play a role in reproductive well-being.
Curious to learn more? You can explore blog reflections on infertility or dive into more fertility research insights .
