Whether you are only starting to think about ttc or you’ve been trying for a while, tracking your fertility through an ovulation calendar can be beneficial. Women are incorrectly taught that all women ovulate on day 14, and if you falsely believe this, you may be missing your fertile window. There are many different ovulation calculators and ovulation tests out there. I am going to start with the simplest and cheapest kind- the fertility awareness method. This ovulation calculator only requires a thermometer and an awareness of your body.
Quick Background of the Menstrual Cycle
In order to truly understand the fertility awareness method, you must understand the menstrual cycle. Day 1 of your menstrual cycle is the first day of your period. From Day 1 to ovulation (somewhere around day 14) your estrogen level is rising (estradiol in the diagram). Once your estrogen level gets to a critical point, your body releases a surge of LH hormone. This LH surge causes your body to ovulate and release an egg. After the egg is released, the ovary releases progesterone. The progesterone maintains a warm and welcoming environment for the egg to implant. If the egg doesn’t get fertilized and implant in the uterus, the ovary stops releasing progesterone, and the uterine lining sheds, inducing a period, and day 1 repeats.
Measuring your Temperatures
The first part of this fertility calculator is measuring your basal body temperature. Your basal body temperature is just a term for your core body temperature at rest. It is one of the two essential parts of the fertility awareness method. You should use an oral thermometer and take your temperature every morning before getting out of bed. Record this temperature. The easiest way to record your temperature is in an app. Glow , Kindara , and Ovagraph are some examples.
Don’t be discouraged if your basal body temperatures don’t create a beautiful graph. Although this would be nice, other things factor into our basal body temperature besides for ovulation. Try to look at the overall trend. It would be ideal to start tracking your fertility months before ttc. This would give you time to look at a few cycles and identify trends. But if you are already ttc you can start charting with your next cycle. Day 1 always equals the first day of your period.
What is Cervical Mucus?
Cervical mucus is the discharge released through your cervix. This is the second part of the fertility awareness method. You may have noticed an increase in discharge after stopping your birth control. That’s cervical mucus! It is different from vaginal fluid. Vaginal fluid is released in the vagina for lubrication in response to sexual arousal. Cervical mucus is important because it is the medium through which sperm swim to reach the egg. If there isn’t enough cervical fluid or if the cervical fluid is “hostile” the sperm aren’t able to reach their destination. If the cervical fluid is too thick and sticky, the sperm get stuck en route. You can see how cervical mucus is important.
How do you check cervical mucus?
This depends on your comfort level. You may notice changes in your underwear- this counts! You can also wipe with toilet paper before you use the bathroom and evaluate what is on the toilet paper. Interesting, when you stool you often eject more cervical mucus. So you may notice more cervical mucus after stooling. You can also check your cervical mucus by placing a clean finger inside your vagina and evaluating what you see on your finger. All methods work.
What are the different types of cervical mucus?
Typically cervical mucus is referred to as dry, sticky, creamy and “egg white”.
|Sticky||Thick, white and tacky or crumbly||infertile|
|Egg-white||Stretchy, clear, slippery||Fertile!|
After your period your cervical mucus will be dry, then sticky, then creamy and then egg-white. Egg-white cervical mucus is the best indicator of peak fertility. Typically this period lasts 3-5 days so take advantage of it while its there! Your cervical mucus may not follow this pattern. But the take-away message here is to look for the “egg-white” discharge or a change in cervical discharge from dry to wet and slippery. This is the discharge that tells you that you are fertile.
When should you have intercourse when ttc?
The fertile period is 5 days before ovulation and 24 hours after ovulation. This is because sperm can survive 5 days in optimal conditions and the egg can survive for 24 hours after ovulation. The only way to know for sure once ovulation has occurred is once there is a rise in basal body temperature. But once you see this rise, ovulation has already occurred and the peak fertile window has passed.
The best way to identify your fertile window is to pay attention to your cervical mucus. Look for that fertile-quality cervical mucus (egg-white consistency cervical mucus). When you have fertile cervical mucus you are likely approaching ovulation. If you have consistent cycles you can subtract back 5 days from the day you normally ovulate. However many women’s cycles change every month which is why paying attention to cervical mucus is ideal. And remember- once you identify a rise in basal body temperature corresponding to ovulation you have one last chance to have sex before you’ve passed your fertile window.
A historic study of 221 healthy women looked at the viability of pregnancies achieved following ovulation as opposed to at the time of ovulation.1
In this study the probability of pregnancy were as follows:
- 4% when intercourse occurred 5 days before ovulation
- 25-30% when intercourse occurred within 2 days before ovulation
- 8% when intercourse occurred within 24 hours AFTER ovulation
- 0% when intercourse occurred more than 24 hours after ovulation
As you can tell from this data, the ideal time period to have sex is within 2 days before ovulation. However, due to the difficult in timing ovulation, it is best to aim to have intercourse daily for the 5 days leading up to ovulation and 24 hours after ovulation has occurred. I say daily, because in men with normal sperm quality, daily ejaculation is ideal.
Low Sperm Count?
If low sperm count is an issue, the recommendation is to have intercourse every other day. This will allow the concentration and volume of sperm to increase during the day of abstinence. In this case, the male partner should also abstain from ejaculation a few days before the fertile window to help increase the volume and concentration of sperm. Save the goods for when it counts!
Does the Fertility Awareness Method Work?
The fertility awareness method is a good first step at understanding your ovulation cycle. It can help you identify when you are fertile and when you ovulate. It can also help you time intercourse to ensure you are taking full advantage of your fertile days. Having a baby is a huge life-altering decision and it makes sense to study and be prepared. The fertility awareness method can also help you trouble shoot when unexpected things happen. For example, if you experience some spotting a few days before your period, this could actually be a sign you are pregnant. This is called implantation bleeding and can occur from the egg burrowing into the uterus. If you were charting your temperatures and you can 13 elevated temperatures you could be more confident that the bleeding is implantation bleeding resulting from pregnancy and not your normal period.
Limitations of Fertility charting
That being said, the fertility awareness method cannot make you ovulate and cannot fix problems outside your control. There are some problems that will require medical intervention. So if you have been charting and having intercourse during your fertile window for 4-6 months without success, you may want to consider seeing a doctor or midwife for a fertility evaluation. It is best to bring your charts with you to these visits to help your provider identify the problem and help you achieve a health pregnancy.
Where do you begin?
I started by reading the “Taking Charge of Your Fertility” by Toni Wescher. It gives you a lot of information and not all of it is relevant but it can help give you a background. It is up to you if you want to purchase a smart thermometer with wifi capability. I purchased a regular thermometer and it worked just fine. Then download one of the apps I mentioned earlier. Wait until you get your next period and start charting on the first day of your period. It is exciting seeing your chart of temperatures. Add in your cervical mucus, especially your fertile cervical mucus.
The more information you input the better. But at a minimum, chart your period, your temperatures and the presence of fertile cervical mucus. Many of the apps out there will automatically identify when you ovulate and when your fertile window is. But always look at it yourself to make sure the information it auto-fills is correct. Charting is the first step, but not the only step. Make sure you follow my 10 Steps to TTC.
- Wilcox, A. J., Weinberg, C. R., & Baird, D. D. (1998). Post-ovulatory ageing of the human oocyte and embryo failure. Human Reproduction, 13(2), 394-397.
- Jennings, V., & Zieman, M. (2010). Fertility awareness-based methods of pregnancy prevention. UpToDate. Version, 18.
- Weschler, T. (2003). Taking charge of your fertility: the definitive guide to natural birth control, pregnancy achievement, and reproductive health. Random House.