Myth: You can get pregnant at any time in your cycle

Once in the midst of a FAM-related conversation, I was faced with a challenging statement from a friend: this method can’t possibly work because I know that you can get pregnant at any time in your cycle.

Let’s deconstruct this and see if this is true.

What is required for pregnancy to occur?

1. A mature, live egg

2. Live sperm

Without both of these factors at the same time, pregnancy is impossible. You don’t hear stories of virgin girls becoming pregnant (Mary aside) because although they may be ovulating, their ovulated eggs are not exposed to live sperm. As an ovulating female, there is no chance for you to get pregnant until live sperm are introduced to your body. Neither do men become pregnant in themselves by just producing sperm. There has to be a live egg available for fertilization. I think we can all agree on this, yes?

After maturity, healthy men produce sperm every day of their lives. They are fertile every single day. That means any day a woman has intercourse, she is exposed to live sperm. In ideal conditions inside a woman’s body (determined primarily by the quality of the woman’s cervical fluid), sperm can live up to five days. In less than ideal conditions, their lifespan is much shorter.

A woman’s fertility, however, is different. She is not fertile every single day because she doesn’t have a mature, live egg available in her body every single day. An egg is matured in an ovary once per cycle, bursts out of the ovary and is available for conception for 24 hours. After 24 hours the egg is dead and can no longer contribute to a pregnancy. In rare cases double ovulation can occur, in that two eggs are released in the same cycle. This is rare, but it can happen. If this does happen, the second egg is always released within 24 hours of the first one. This is not controversial or disputed; this is basic biology.

So at the very most, a woman’s body contains a mature, accessible, live egg for a maximum of 2 days. Combine this with the understanding that healthy, live sperm can survive inside a woman’s body in ideal conditions for 5 days, and you have a total fertile phase of 7 days.

Outside of these 7 days, the woman can not get pregnant. With no live egg present, pregnancy cannot occur. The only time pregnancy can occur is in the days around ovulation.

So can you get pregnant at any point in your cycle? No.

The better question, though, and the one I didn’t think to ask until after the fact is: if you are not charting, how do you know what point of your cycle you are in? You don’t.

You may know what day your cycle began if you record the date your flow started and understand the difference between spotting and bright red flow. But even that somewhat obvious sign can be misleading.

Was it truly a new cycle with the flow originating from the shedding of the uterine lining?

Was it mid-cycle spotting?

Was it anovulatory bleeding?

Was it implantation spotting?

Was it bleeding completely unrelated to your cycles, caused by a medical condition?

If you’re not charting, you don’t know. You can guess, but you don’t know. It is nearly useless for women who don’t chart to speculate about the progression of their cycles. Without charting, you don’t know any of the above questions, nor do you know the length of your follicular phase, ovulation date or length of your luteal phase. You may know that there is blood coming out of your vagina, or that you haven’t had blood come out of your vagina in a while, and surprise, you’re pregnant.

You cannot get pregnant at just any time in your cycle. But more importantly, if you’re not charting, you cannot know what part of your cycle you’re in.