EP45: Why Your Child’s Health Begins Before Conception

It’s well known that the first 1000 days — from conception to a child’s second birthday — are crucial for their development. But recent scientific discoveries show that this story begins even earlier. Epigenetics, an emerging field of research, reveals that the environment and lifestyle of parents before conception can have a lasting impact on their child’s health.

In this episode of 1000Deeg, Dr. Agnès Collet, a medical biologist specializing in human genetics and functional medicine, shares insights into these fascinating discoveries and their implications for early childhood development.

"Our Environment Influences Gene Expression"

"A child naturally inherits their genetic material — 50% from the mother and 50% from the father. But we now know that this is not a fixed program," explains Dr. Collet. "The environment, lifestyle, and diet all influence how those genes are expressed. Epigenetics helps us understand how certain genetic predispositions can be activated or, on the contrary, suppressed by parental lifestyle choices."

This influence starts long before birth. “There are epigenetic markers that determine how our genes are expressed, and these markers are shaped not only by the baby’s environment but also by the parents’ lifestyle before conception,” she emphasizes.

Research shows that parental stress, nutrition, and exposure to toxins can modify these markers and impact the future child's development. “There’s a biological continuity between generations that goes far beyond simple genetic inheritance,” Dr. Collet explains.

The "Preconception Window" — A Critical Period

Traditionally, the first 1000 days are defined as pregnancy plus the first two years of a child’s life. But according to Dr. Collet, this period should be extended: The 100 days before conception are just as crucial.

“Gametes — that is, sperm and egg cells — mature about three months before conception,” she explains. “And their quality is directly influenced by the parents' environment and lifestyle.”

This means that the health and lifestyle choices of parents before pregnancy can significantly impact the baby’s future well-being. “That’s why we now emphasize the importance of the preconception period, which starts well before pregnancy is confirmed,” says Dr. Collet.

Which factors should parents focus on? Diet, sleep quality, stress levels, and exposure to toxins are among the most influential.

"A Mother’s Diet Can Influence the Baby’s Gene Expression"

Among the most studied factors, parental nutrition — especially the mother’s diet — plays a crucial role. “Research has shown that a diet rich in fats and ultra-processed foods during pregnancy can alter the expression of genes linked to the baby’s metabolism,” explains Dr. Collet.

“What the mother eats can have a long-term impact on how the baby’s body processes fats and sugars, increasing the risk of metabolic diseases later in life.”

But it’s not just about the mother. “The father’s lifestyle also plays a significant role,” she insists. “Stress, alcohol consumption, and lack of sleep can affect sperm quality and thus influence the unborn child.”

Attachment and Development: A Biological Influence?

Beyond genetics and nutrition, the emotional bond between parents and their baby plays a major role in development. “We now know that the quality of attachment influences stress regulation and even gene expression,” explains Dr. Collet.

Studies have shown that children who experience insecure attachment or early separation may develop long-term changes in their stress response. “In both animals and humans, we see that care, love, and emotional security in the early years have a measurable biological impact. Certain epigenetic markers are shaped by the quality of early relationships.”

She refers to a study conducted in England on children who had experienced neglect or abuse. “Researchers found that re-establishing a strong bond with a parent or caregiver could modify certain epigenetic markers. This shows that nothing is set in stone and that love, presence, and emotional security can have a biologically restorative effect.”

But these insights also raise social questions: Do we give parents enough time and support to build these essential bonds? “I believe there’s a real need for reflection here,” says Dr. Collet. “Attachment time doesn’t end with parental leave. Today, many parents return to full-time work early and lack support. Time has become a major public health issue — and we need to take it more seriously.”

A Gap in Preventive Care: Why Don’t We Act Earlier?

Despite these scientific advances, preventive care is still largely focused on pregnancy and early childhood. “Today, we offer good support to pregnant women, but we talk far too little about what happens before conception,” regrets Dr. Collet.

She highlights a paradox: While scientific knowledge advances, public health policies are slow to adapt. “Why don’t we better inform future parents early on? Why wait until pregnancy to talk about nutrition, toxins, or stress management when we know these factors play a role long before?”

Some countries have started introducing preconception consultations, but this practice remains uncommon. “There’s enormous potential to reduce chronic diseases by acting earlier,” she emphasizes.

A New Approach to Early Health?

By expanding the first 1000 days to include a preconception period, preventive medicine could significantly reduce the risk of chronic diseases and improve the long-term health of future generations.

“We’re starting to realize how important prevention is in modern medicine, but we need to go further,” concludes Dr. Collet. “Advances in genetics and functional medicine provide us with powerful tools to support parents long before the baby is born.”

This shift invites us to rethink early childhood health — not as something that starts at birth, but as a process that begins much earlier, shaped by the choices and environment of parents well before conception.