For nearly all of human history, women spent the majority of their fertile...

For nearly all of human history, women spent the majority of their fertile years either pregnant or breastfeeding. This wasn’t just a cultural norm—it was an evolutionary reality. The way women’s bodies function, the way their hormones regulate, and the way their psychological and emotional well-being are structured all developed in response to this constant state of nurturing life, either in the womb or at the breast.

Yet today, women are having zero, one, or at most two children—a stark contrast to the reproductive patterns that shaped human evolution. This drastic deviation from the norm may be a key factor in the rising rates of depression, anxiety, and psychiatric disorders among modern women.

1. The Evolutionary Expectation: Constant Pregnancy and Breastfeeding

For hundreds of thousands of years, the typical reproductive cycle for a fertile woman followed this pattern:

Conception → Pregnancy → Birth → Breastfeeding (which suppresses ovulation) → Repeat

This cycle continued throughout the majority of a woman’s reproductive years, from puberty until menopause.

Due to lack of birth control and natural fertility, women would have 6-10 pregnancies on average in their lifetime.

This means that for nearly all of human existence, women were biologically adapted to be in a constant state of pregnancy or lactation. It was the default condition for a healthy, fertile woman.

2. The Shift to Modern Reproductive Patterns

In the modern era, the introduction of birth control, delayed marriage, and career-focused lifestyles has resulted in:

Many women having zero children (unheard of historically outside of infertility).

Some women having only one or two children, far below the historical average.

Long periods of non-pregnancy and non-lactation, which were biologically and hormonally rare in pre-modern women.

For most of history, a woman under 40 who was neither pregnant nor breastfeeding was a biological anomaly. Today, that anomaly has become the norm.

3. The Physiological and Psychological Consequences of Low Fertility

Women’s bodies are designed to experience continuous cycles of pregnancy and breastfeeding, which regulate hormones, brain chemistry, and emotional well-being. When these processes are interrupted or drastically reduced, it can have serious effects:

Hormonal Dysregulation

Pregnancy and lactation stabilize hormones like estrogen, progesterone, and oxytocin—all critical for mood regulation.

Modern women experience far more unregulated menstrual cycles, which can lead to hormonal imbalances contributing to anxiety and depression.

Loss of Oxytocin and Maternal Bonding Effects

Breastfeeding releases oxytocin, the “love hormone,” which promotes feelings of well-being, calm, and emotional connection.

Without pregnancy and nursing, women miss out on this repeated natural mood enhancement, which could contribute to a rise in loneliness, detachment, and depression.

Lack of Purpose and Instinctual Fulfillment

Human beings evolved in a tribal, child-rearing environment, where women were nurturing and surrounded by small children.

The modern lifestyle of solitary work, digital distraction, and delayed family formation leaves a deep psychological void for many women.

Many women report a deep sense of emptiness, disconnection, and lack of fulfillment, despite being told by society that careers and independence should make them happy.

4. The Link Between Low Fertility and Rising Psychiatric Disorders in Women

Modern women are experiencing historically unprecedented levels of depression, anxiety, and psychiatric disorders, particularly in industrialized nations where birth rates have plummeted.

Studies show that women without children report higher rates of depression and anxiety than mothers.

Countries with higher birth rates tend to have lower rates of female mental illness compared to nations with extremely low fertility.

Many women who spend years focusing on careers and delaying children experience a mid-life crisis when they realize they are biologically out of time.

5. A More Natural Alternative: Aligning with Evolutionary Biology

Rather than treating pregnancy and child-rearing as an inconvenience or burden, we should recognize that it is a biological necessity for most women’s health and well-being.

Encouraging earlier family formation allows women to align their biology with their life trajectory, rather than working against it.

Rebuilding community support for mothers can help alleviate the pressures of modern parenting while maintaining the evolutionary benefits of child-rearing.

Valuing motherhood as a fulfilling and meaningful path, rather than dismissing it in favor of career ambitions alone, can help restore balance to women’s lives.

Conclusion: The High Cost of Ignoring Biology

For almost all of human history, women were either pregnant or breastfeeding for the majority of their fertile years. This was not an accident—it was how human biology and psychology evolved to function optimally. The modern world, by reducing pregnancy and child-rearing to near-zero levels for many women, has created an unnatural state of being that likely contributes to the sharp rise in female depression, anxiety, and dissatisfaction.

While modern advancements have given women more choices, ignoring the biological need for pregnancy and maternal bonding comes at a cost. Understanding this reality may be the key to reversing the crisis of mental health in modern women and restoring a sense of fulfillment, purpose, and stability.