The Hidden Timeline of Fertility: Why Preconception Health Starts Months Before Pregnancy

Do you have babies on your mind? Are you planning on trying to conceive in the near future? Have your social media ads been aggressively pushing prenatals and “magic baby dust” at you?  

If this sounds familiar, then it’s possible you have already started looking into some version of preconception care and if you haven't, don't worry, I’ve got you.

But why all this emphasis on preparing ahead of time?

It’s true that many pregnancies come as a surprise and not everyone has the luxury of planning several months in advance.  However, there is an increasing awareness of the value of paying closer attention to your health before becoming pregnant, particularly as infertility rates continue to rise.

There are many benefits to doing a bit of prep work, but before we talk about what you can do, it's important to understand why it's a conversation at all. The health of your eggs—and by extension, your future child—starts long before conception.

In very simplified terms, pregnancy occurs when: an egg is released from the ovary during ovulation, sperm meets egg, fertilization happens, the resulting embryo implants in the uterus and starts to grow.

But what happens before ovulation? How does the egg even develop?

The process of egg development—called oogenesis—actually begins before you’re even born. 

You are born with all the cells that could potentially become eggs.

Before birth, a person with ovaries develops primordial germ cells—about 1 to 2 million of them. After birth, these develop into primordial follicles, each containing an oocyte (a future egg) surrounded by nourishing cells. These oocytes begin a special cell division process, but this process pauses at its very first stage until puberty.

When do follicles start maturing again? 

During puberty. This is when reproductive hormones become more active in your body. Due to this, those primordial follicles “wake up” and begin to grow. Each month, about 1,000 follicles begin developing—but usually only one is selected for ovulation. 

It takes about a year for just one of those follicles to fully mature into an egg!

What happens during that year of growth?

Most of that time—roughly 9 to 10 months—is called the pre-antral phase, when the follicle grows without hormonal influence.

The oocyte grows larger and starts developing hormone receptors, first becoming a primary follicle and then a secondary follicle. At this point, it's still in the process of dividing, and it's adding layers of nourishing cells.

The second part of that year is called the antral phase.  This phase starts when a fluid-filled sac (called an antrum) forms inside the follicle.  Once this happens, hormones like FSH (follicle-stimulating hormone) and LH (luteinizing hormone) really step in to help the follicle grow.

The antral phase lasts about 75–85 days, or roughly two menstrual cycles. During this time, one follicle becomes dominant and is ultimately the mature egg that is released during ovulation in the third cycle.

For those who are more visual, here's a quick overview.

1 YEAR

Primordial Follicle - Primary Follicle -    Secondary Follicle - Ovulation

Pre-Antral Phase Antral Phase

NO hormones HORMONES

9-10 months  75-85 days

So what does all this have to do with preconception care you may wonder?

Everything.

Your overall health affects your cellular health—including the cells that develop into eggs. That means nutrition, environment, sleep, stress, and movement all play a role in egg quality.

How does the 3 month fertility window play a role?

Allowing for a 3-month window to start making changes before conception is emphasized so much because that’s the duration of the antral phase—when follicles are hormonally active and most influenced by your health. Making positive changes during this window can have a big impact on egg quality.  If you start making changes earlier than that, fantastic!

Is preconception care important for sperm health too?

Absolutely.  Sperm cells are the male equivalent of the egg and responsible for 50% of the DNA of your child.  They are very susceptible to cellular damage and the overall trend of sperm quality has decreased significantly in the last few decades.  Additionally, approximately 50% of infertility cases are male-factor related.  The good news here is that sperm, just like eggs, have a 3 month window for development; so any changes made to improve sperm health should start taking effect after about 3 months.

Overall, the benefits of preconception care can have a lasting impact, not only on your health, but the health of your future child.

Curious about how to support your fertility naturally?

At Dragonfly Integrative Medicine, I offer individualized preconception care that meets you where you are—whether you're planning months ahead or just starting to think about trying.

Let’s work together to prepare your body for a healthy pregnancy.

References

1. Cox E, Takov V. Embryology, Ovarian Follicle Development. In: StatPearls. Treasure Island (FL): StatPearls Publishing; August 8, 2022.

2. Holesh JE, Bass AN, Lord M. Physiology, Ovulation. In: StatPearls. Treasure Island (FL): StatPearls Publishing; May 8, 2022.

3. Williams CJ, Erickson GF. Morphology and Physiology of the Ovary. In: Feingold KR, Anawalt B, Blackman MR, et al., eds. Endotext. South Dartmouth (MA): MDText.com, Inc.; January 30, 2012.