When you’re trying to get pregnant, knowing your fertile window helps you know your prime time to have sex. You figure this out through ovulation monitoring!
Here’s a little recap on why timing is so important when you’re trying to get pregnant.
Even though most of us were taught as youngsters that it can happen at any time, that’s not reeeeeealy the case.
- To get pregnant, a sperm needs to meet an egg. (Or, as we like to think about it, an egg allows a sperm into her inner circle.)
- A new egg is ovulated each month. When we say “ovulation”, that is when the egg is released from the ovary.
- Once ovulation occurs, the egg stays viable for 24 hours.
- A sperm needs to meet the egg during that 24 hour window in order to get pregnant.
- Sperm can live in the reproductive tract for up to 5 days.
- This means the fertile window is:
- the 5 days before ovulation – because the sperm can be alive inside for that long, waiting for the egg to be released
- the day of ovulation itself – because the egg is ready for sperm anytime in that 24 hour time frame
- the day after ovulation – because most people don’t know what time they ovulated. If you ovulated an night, the egg is able to be fertilized whole next morning and afternoon!
Monitoring ovulation helps identify the day you will likely ovulate.
There is no best method, but some are definitely more user friendly and more accurate than others.
I typically encourage people to track their periods with the calendar method AND either cervical mucus monitoring OR ovulation prediction kits (also called luteinizing hormone – LH – kits)
Here’s the run down on each:
What it is: tracking the days of your period on a calendar or app
Based on theory that: ovulation occurs, for most women, 14 days before your next period.
How to do it:
- Day #1 is the first day of your period (normal flow, not just spotting)
- The number of days in your cycle is from the first day of your period to the day before your next period. So a 28 day cycle is Day 1-28, and then your period starts on Day 29. Since your period started, instead of saying Day 29, it is now called Day #1 again.
- Most women ovulate 14 days before their next period. If you have a 28 day cycle, 28-14=14, so expect to ovulate on day 14. If you have a 30 day cycle, 30-14=16, so expect to ovulate on day 16.
- Super easy and cheap!
- It can help you get in tune with your cycle and can identify irregular periods as well
The not so good:
- Most women have a range of cycle length – for example, 28-31 days. That means ovulation could occur anywhere from D14-17, and you won’t be able to verify until you have your period. This is why, if you are intent on knowing the day of ovulation, we recommend using an additional method
- If you’re using an app for this, the technology averages your previous cycle lengths to give you your day of predicted ovulation. If your cycle length is 28-32 days, it will average that to a 30 day cycle and predict ovulation on Day 16, when in fact you may be ovulating anywhere between D14-18 that month. If you forget to document for a month, the data is skewed.
Ovulation Prediction Kits (LH monitoring)
What it is: Using urine test strips to identify when the LH (luteinizing hormone) surge occurs.
Based on theory that: Luteinizing hormone (LH) tells the ovary to ovulate. It increases dramatically about 48 hours before ovulation then takes about 12 hours to get into the urine. This means a positive urine occurs about 36 hours before ovulation.
How to do it:
- Buy a test kit from any pharmacy store (we don’t recommend any specific brand)
- Identify a range of dates where ovulation may occur (based on calendar method / period tracking)
- Start testing several days before expected ovulation – that way you know you have a baseline negative test and can tell when there is a change.
- If you haven’t been tracking your cycle, start checking on Day #7 of your cycle (Day #1 is the first day of normal flow).
- Drink a normal amount of water / fluids each day – don’t overhydrate as it may dilute the urine.
- Ideal time to check urine LH is between 10am-3pm.
- Check daily around the same time until you have a positive. Once you have that positive, stop! You will/should ovulate around 36 hours later.
The good: Unlike some of the other methods, LH is positive before ovulation – this helps you time sex if you’re trying to get pregnant
The not so good: LH can be artificially elevated with certain medical conditions, like PCOS. A reported 7% of cycles will have a false positive rate
Cervical mucus monitoring
What it is: monitoring cervical mucus (which is the same as vaginal discharge)
Based on theory that: cervical mucus changes over the course of a menstrual cycle. Lubricating, clear, egg-white consistency cervical mucus is a sign of ovulation
How to do it:
- Cervical mucus is vaginal discharge.
- Place one or two fingers in the vagina – insert them until you feel your cervix (it feels like a small ball with the consistency similar to your nose). Remove them and look at the discharge.
- Remember these changes:
- After your period, there will be a few days with no discharge.
- The discharge then becomes clear and increases in amount until it is like egg-whites.
- After ovulation, discharge become white and slightly more tacky
- Then your period starts again
The good: It helps women understand normal changes in vaginal discharge during the course of a cycle
The not so good: cervical mucus / vaginal discharge can be obscured by semen or vaginal infections. It can be confusing to tell the exact day of ovulation because the clear slippery discharge can be present for several days. That slippery discharge is the fertile window though, so use it as a reminder to have sex those days, even if you aren’t sure of the exact day of ovulation!
If you’re interested in more ovulation monitoring info, head over to FemaleHealthEducation.com! You’ll have first dibs on our upcoming course, Boosting Fertility and Preparing for a Health Pregnancy.
I am a board certified OBGYN at Cedars Sinai in Los Angeles.
I am co-founder of Female Health Education, a platform offering digital courses, striving to empower females through health education.
My passion is promoting and demystifying health information to the public. My blog, Dr. Sara Twogood’s LadyParts Blog, provides comprehensive information about fertility, pregnancy, and gynecology topics. I am on the medical board for the period tracker app Flo; contribute as a medical expert for pregnancy app and website The Bump; and serve on the Byrdie Beauty and Wellness Review Board (Byrdie.com). I have been featured as an expert for the podcasts The Dream and Her body, Her Story and quoted in numerous online and print publications.
I am honored to be named “Top Doctor” in Los Angeles magazine for years.