Peak Fertility Days: When am I Most Likely to Get Pregnant?

Are you thinking about trying to have a baby? If so, congratulations! Wondering where to start? You've come to the right place. Planning for pregnancy starts with knowing and understanding your menstrual cycle, as this will help you determine your peak fertility days— the days when you’re most likely to get pregnant.  

Luckily, there are different methods to calculate the best time to conceive, which we’ve compiled in this practical pregnancy guide. Much will depend on whether or not your cycle is regular, something that varies from person to person. If you’re looking to become a parent or expand your family, keep reading to learn all about the process of calculating when you’re most likely to conceive.  

Fertility and Your Menstrual Cycle

To better understand fertility, let’s review a few basic concepts. Fertility describes a person’s ability to reproduce: to both conceive and carry a pregnancy to term. 

Fertility can be affected by anomalies in ovarian function, age, or menstrual cycle irregularity. These factors can reduce fertility and therefore the ability to get pregnant, which is referred to as infertility.

Keep in mind: The menstrual cycle begins with the first day of bleeding and ends one day before the bleeding starts again. A normal menstrual cycle can vary between 21 and 36 days. Contrary to popular belief, a regular cycle isn’t necessarily 28 days. In fact, only 10-15% of menstruating people have 28-day cycles. 

What makes a cycle regular is how consistently menstruation takes place. In other words, if it comes on the same date every month, the cycle is regular. If it comes on different days and is unpredictable, the cycle is irregular. 

The menstrual cycle has three phases

  • Follicular: This is when a menstruating person bleeds, which can last from 3-7 days during this phase. 
  • Ovulatory: This phase is when the ovaries release an egg for fertilization.  
  • Luteal: This phase prepares the uterus for a fertilized egg to implant.  

After this time, if the egg goes unfertilized— which is what the body prepares for during these phases— both it and the uterine lining are shed. This results in bleeding and is the start of a new menstrual cycle. 


Ovulation takes place in the second phase of the cycle and is when a menstruating person is most likely to conceive.

Keep in mind: In a 28-day cycle, ovulation takes place around day 14, though this will depend on the person’s regularity. During these days, the ovary releases a mature egg, which travels down the fallopian tube and remains for 12-24 hours while it awaits fertilization. 

The fertile ovulation phase

The fertile phase is medically defined as the cycle that takes place around ovulation. Also known as the “fertile window,” this includes the day the egg is released from the ovary, as well as the five days prior. Having sex during this time will give you the highest chance of concieving. 

For example, if someone has unprotected sex on their day of ovulation, they can get pregnant that same day or within a 24 hour period. 

Identifying the day of ovulation is easy for some, but can be difficult for those with an irregular cycle. 

Fertile days with irregular menstruation 

For those with irregular cycles, fertile days still occur around the ovulatory phase. The challenge is determining when this day happens. But don’t worry, we’ll help you figure it out! 

The first thing to know is that there's a range of time when this can occur (between the 11th and 21st day of a 28-day cycle). Ovulation always takes place in the middle of the cycle. The second important thing is to familiarize yourself with the telltale signs of ovulation.

Keep in mind: if you want to use a more precise method, we recommend using an ovulation test or kit. These kits measure luteinizing hormone levels present in urine. These hormones are especially present during your period. When you get a positive result, you can calculate that ovulation will occur 36 hours later.

The main signs of ovulation

It’s easier to figure out when you’re ovulating if you have a regular cycle. It can get a bit trickier if your cycle is irregular. There are a few signs that you can look out for during your ovulation phase:

  • Increased resting body temperature (called basal temperature) 
  • Increased volume and texture of vaginal fluid (cervical mucus) 

These signs are the easiest to identify and tend to be accompanied by an increased libido, sharp abdominal pain, and changes in your breast size. One of the most popular methods to calculate when you’re ovulating is the fertility calendar. This calendar can help you establish when your ovulatory phase is with a relatively reliable degree of certainty. 

How Can I Create my Fertility Calendar?

Article Image

You’re in luck, creating a fertility calendar is easy! First, make sure you have a clear understanding of your menstrual cycle’s rhythm and keep track of it. If you’re regular (your period comes on the same day every month), write down how many days pass between the first day of your previous period and the first day of your next period.

If your cycle is irregular, you can use a calendar or a fertility calculator. The best thing to do is pay attention to the signs above or consult your doctor to determine and treat the cause of your cycle’s irregularity.  

Cycles can vary throughout the year. A solution is to keep track of your cycle every month for six months and then calculate the average. Once you’ve established how long your menstrual cycle is on average, follow the steps below to create your calendar: 

  • Create a calendar with the days that you collected
  • Identify the three phases (follicular, ovulatory, and luteal) and color-code them
  • Highlight the corresponding days according to each phrase’s duration
    • Follicular (days 1-13): the first five to seven days of this phase when you have your period
    • Ovulatory (day 14): this phase can span three days from start to finish, so you’ll want to mark from days 13 to 15 
    • Luteal (days 15-28)
  • Your peak fertile days will occur five days before the ovulation date and one day after, for a total of seven days 
  • The rest of the days, except those when you’re bleeding, are considered “less fertile days” 

Now you have your own fertility calendar!

Keep in mind: These steps are based on a regular 28-day cycle. If your cycle is shorter or longer, we recommend the following: 

  • First, establish your fertile days (you can use the method below to do this)
  • Calculate your ovulation day, which normally takes place five days after the start of your fertile days 
  • Finally, calculate the other phases during the rest of the days like we showed you above 

Remember that you can use an ovulation calculator to provide an estimate of your peak fertile time. You’ll just need the average duration of your period and the date of the first day of your period. 

To determine your peak fertility days, try using the rhythm method or the Ogino-Knaus method, which can be used either to conceive or to prevent pregnancy. It’s ideal for those with irregular periods. This method consists of keeping a six-month log of the menstrual cycle, recording your shortest and longest periods, and subtracting 18 and 11, respectively. 

Here’s an example:

Article Image

How Can I Maximize My Chances of Conceiving? 

If you’re trying to get pregnant, you’ll probably want to use every means at your disposal. Information is one of the most powerful tools, which is why we’d like to give you a few tips to help increase your chance of getting pregnant.

Diet and lifestyle

A balanced diet has plenty of benefits, including keeping stamina levels high, maintaining a healthy weight, and reducing risk of illness. It also increases your likelihood of getting pregnant. In fact, a study conducted by scientists in Spain demonstrated the important relationship between diet and fertility. 

Excessive consumption of trans fatty acids, saturated fats, and carbohydrates have a negative impact on fertility for all sexes. Diets rich in omega-3 fatty acids, monounsaturated fats, complex carbohydrates, and fiber can have an extremely beneficial effect on fertility. A healthy diet and a healthy lifestyle go hand in hand, which is why the Mayo Clinic recommends

  • Not smoking 
  • Decreasing or eliminating alcohol intake
  • Limiting caffeine consumption
  • Moderate amounts of exercise (more than five hours of exercise per week can impact ovulation)
Keep in mind: Maintaining a healthy diet and lifestyle increases your chances of getting pregnant. To prevent complications, eat a diet rich in vitamins A, D, C, and E, as well as calcium, zinc, iron, iodine, selenium, vitamin B12, and folic acid. To avoid ovulation challenges, staying at a weight that’s neither too high nor too low is essential.

Other best practices

Another tip to increase your likelihood of conception is to have sex often, especially when you’re ovulatating. Keep in mind that sperm can live in the uterus for up to five days. Having unprotected sex on days before the ovulatory phase increases your probability of getting pregnant.

How Does Age Affect Fertility?

Biologically, people between the ages of 20-30 have the highest chances of getting pregnant. While peak reproductive capacities decrease after this time, it’s still possible to conceive.

Keep in mind: As you get older, the less likely you are to become pregnant. Some women start menopause in their mid-40s (if it starts earlier, it’s called precocious menopause). This stage is associated with the end of menstruation and ovulation.  

According to Stanford Children’s Health, the number of women having children in their 30s is at the highest it’s been in the past 40 years. There are certain age-related risks of pregnancy, including miscarriage, genetic alterations, high blood pressure, gestational diabetes, and labor complications.   

If you’d like to delay your family planning, consider methods to store your eggs. Freezing your eggs is one of the best ways to preserve them for use later on. A lot of people get pregnant in their 30s or 40s and deliver perfectly healthy babies. This lets you conceive when the time is right for you and your family. 

The Pill and Fertile Days

The purpose of different oral contraceptive methods is to prevent ovulation. When someone takes the birth control pill correctly (every day at the same time), it stops the ovulation process from taking place. This reduces the likelihood of pregnancy, even during unprotected sex. 

Keep in mind: The pill is 99% effective when taken correctly, but if you miss a pill, the effectiveness decreases to 91%. The Food and Drug Administration (FDA) provides a complete guide to contraceptive methods.

The Importance of Consulting a Doctor

Article Image

To go to the doctor, or not to go? That’s a common question to ask, especially if you’re planning on getting pregnant. Staying healthy is the most important thing you can do to increase your likelihood of conceiving and having a smooth pregnancy. This becomes even more important as you get older. 

Keep in mind: An irregular cycle is linked to other imbalances or anomalies. Consult your OB/GYN to evaluate the causes and find the best solution when you’re ready to start trying to get pregnant. It’s also just as important to see your gynecologist on a regular basis to prevent conditions that could compromise your reproductive health. 

We know how important it is to keep you and your family healthy, which is why we’d like to remind you that PODERsalud (the SABEResPODER healthcare plan) provides consultations via telemedicine from your phone with medical professionals who speak your language. Your membership saves you money by providing a wide variety of discounts. 

Frequently Asked Questions

How do I calculate ovulation with polycystic ovary syndrome? 

If you have polycystic ovary syndrome (PCOS), getting proper medical treatment is indispensable. This condition can result in a lack of ovulation, making it nearly impossible to conceive. 

Once your PCOS is managed, the best way to calculate your ovulatory phase is similar to how you’d do so with an irregular period. You can pay attention to the ovulation signals or measure your luteinizing hormone levels using a urine test. You can also take a blood test to measure your progesterone levels.

Can I get my period without ovulating? 

Yes, absolutely. This is referred to as an anovulatory cycle. Although this can happen during one cycle and then return to normal, it’s important to see your OB/GYN to make sure everything is okay. This phenomenon is commonly associated with infertility due to hormonal alterations.

In fact, anovulatory cycles are a symptom of hyperprolactinemia and polycystic ovary syndrome. It can also be linked to diabetes, depression, overexercising, and taking antidepressants or medicines with progestin or estrogen.

Can I get pregnant during my period?

Though it’s unlikely, it is possible to get pregnant during menstruation. 

Menstruation refers to the days that you bleed. It takes place during the first few days of your cycle. Ovulation occurs halfway through your cycle, opening a fertility window when your chances of conceiving increase considerably. While it is possible to get pregnant on other days outside this window, the chance of it happening is lower. 

Can I get pregnant the first time I have sex?

Absolutely! You can get pregnant every time your body is fertile. Even if it’s your first time having sex, there's a possibility of pregnancy whenever you don’t use proper protection. 

Get to Know Your Cycle and Take Control of Your Fertility! 

Everyone should know how their body works, especially when it comes to their period. This knowledge helps you be aware of any issues that might require medical attention and help you plan your family on your own terms. Remember, SABEResPODER