Dr Eugen Jonas’ Lunar Fertility Calculator

Every Woman Must Know About Dr Eugen Jonas’ Lunar Method and Fertility Calculator

I have always been aware of my hormonal cycle. However, when I discovered that women have a second fertility cycle running parallel to the hormonal one, I was amazed.
In other words, women can be fertile twice in a month, and it can happen even on so-called “impossible days.” So how is that possible? Let’s dive in…

The Origins of the Lunar Fertility Method

In the 1950s, during heated debates about abortion laws in Russia and Hungary, women and the medical community faced a shared challenge: how to avoid the physical, mental, and emotional repercussions of unwanted pregnancies.

A young Slovakian doctor named Eugen Jonas, working in Nitra, asked a groundbreaking question: “How can we plan pregnancies and prevent unwanted ones naturally?”

Traditionally, physicians knew that the Moon influenced women’s fertility cycles. Therefore, Dr Jonas recalled the ancient Babylonian saying:

“A woman is only fertile during a certain phase of the Moon.”

This belief aligned closely with fertility astrology and ancient moon-based pregnancy planning, which have existed in various cultures for centuries.

The Discovery: Two Fertility Cycles

Dr Jonas began to study the connection between the Moon and women’s reproductive health. Over time, his research revealed that, alongside the hormonal cycle, women have a lunar fertility cycle determined by the Moon’s position and phase at the time of their birth.

He tested his theory on family and friends, and, for example, he found strong evidence for this second cycle in many cases. Later, with the support of Prague gynecologist Jiri Malek, Dr Jonas conducted more research at the Maternity Clinic in Bratislava, confirming his findings.

Meanwhile, communist-era restrictions almost kept his work hidden from the West. Nevertheless, Dr Jonas persisted, uncovering deeper links between lunar phases and female fertility — a practice now often referred to as lunar birth control or the moon conception method.

How the Lunar Fertility Calculator Works

The standard medical method of predicting delivery dates — using the first day of the last menstrual period — ignores the lunar cycle and is often inaccurate. Instead, Dr Jonas’s Lunar Fertility Calculator works differently:

He calculated fertile days based on the Moon’s position and phase at a woman’s birth. A woman is most fertile during the three days before the Moon reaches the same phase it had when she was born. This method can predict both fertile windows and baby gender with remarkable accuracy. This approach blends astrological fertility tracking with precise moon phase calculations, offering a natural alternative to hormonal contraception.

Baby Gender Prediction & Accuracy Rate

According to Dr Jonas:

If conception occurs when the Moon is in a masculine zodiac sign (Aries, Leo, Libra, Sagittarius, Aquarius, Gemini), there is a higher chance of having a boy.

If conception occurs in a feminine sign (Taurus, Cancer, Virgo, Scorpio, Capricorn, Pisces), a girl is more likely.

In addition, over decades of research, Dr Jonas claimed a 97% accuracy rate for predicting fertile days and gender. This makes it one of the most precise forms of natural pregnancy planning known.

Why This Matters for Women Today

Knowing your lunar fertility days is empowering, whether your goal is conception or natural contraception. Once you identify these days, you can plan intercourse three days before and after your peak lunar fertility window to increase or decrease your chances of pregnancy.

While other health factors also play a role, awareness of both your hormonal and lunar cycles gives you the power to:

Plan pregnancy more consciously.
Reduce the risk of unwanted pregnancy without hormones.
Predict your baby’s gender with greater accuracy.
Explore moon phase fertility tracking as part of a holistic approach to reproductive health.

Discover Your Own Lunar Fertility Days:
Want to find out when your personal lunar fertile window occurs? Use a lunar fertility calculator and explore how the Moon may be influencing your reproductive cycle. Combining this with fertility astrology can offer a deeper, more personalised understanding of your conception potential.