Trying to get Pregnant: How to Calculate Your Fertile Period to Achieve Pregnancy

A number of married women, who have been trying over time to achieve pregnancy have been asking this question on how to know their fertile days, during which they can have sex & get pregnant.

Image Credit: Britannica

Fertile days refers to the days in your menstrual cycle during which the chances of getting pregnant are very high.
Know it, that there is no guarantee that pregnancy would be achieved, because that depends on a number of factors including the fertility status of both man & wife (including sperm/egg counts, quality, etc). All factors being normal, a woman should be able to achieve pregnancy when she has sexual intercourse during her fertile period.

Before we begin on how to know your fertile days, let’s ask this question, Do you know that there are only 8 days in your entire menstrual cycle during which you can possibly get pregnant if you have sex and there was release of viable sperm?
For the remaining days of the cycle, you can have sex with your husband, and there would be no pregnancy. This is the concept of fertile days/period.

Things you need to know first;

  1. The sperm of a man can survive in the body of a woman for up to 5 days.
  2. A woman’s egg can survive in her body, waiting for a sperm, for up to 24hrs.
  3. For pregnancy to occur, a sperm must meet an egg to fertilize, and implant successfully in the womb (uterus).

If none of these happen, pregnancy does not occur.
To achieve pregnancy, we have to;

  1. Target sexual intercourse to be close to & in the ovulation day as much as possible.
  2. Have sex every 2 days within your fertile period. That is to have sex on monday, Wednesday, Friday, etc.
  3. Avoid activities that unbalances your body hormones. A woman’s body is very hormone sensitive. Very stressful activities or exercises can alter your hormones and can cause your body not to ovulate for a particular month.
  4. Ensure there are no other medical conditions that prevents the sperm & egg from meeting and fertilization. See possible conditions here.

How Do You Know Your Fertile Days?
This days which are fertile for you can be calculated using the calendar method.
Here, follow these steps;

  1. How long is your menstrual cycle: That’s the number of days between the first day you start seeing your menses (bleeding) and the next one. For you to do this. Go on a calendar & mark the first day of this period (write day 1 there), and then mark the first day of your next period. Then count the number of days between them, starting from day 1.
    E.g, if 4th may 2020 is the first day your bleeding started (that would be day 1), then if the next bleeding starts on the 30th of may (that’s day 1 for the next cycle). Then from 4th may to 30th may is 27 days. So the menstrual cycle length is 27 days. To be sure about this, you should do this for at least 3 cycles to know if your days are consistent.
    For most women, it is 28 days. For some others, it varies, some 26, some 27, some 29, some 30. Anything between 21-35 is normal. If yours is less than or more than this, please, go see your doctor. You could talk to our Specialist Obs & Gyn @Naijaobgyn.
  2. Know your Probable ovulation day range: every month (cycle), a woman’s body would release an egg, which can develop into a baby, if fertilized. The ovulation day, is the day that the ovary of a woman would release that egg for that month.
    The ovulation day is usually 14 days from the end of the cycle. Hence, it depends on your menstrual cycle.
    if your menstrual has 28 days, your ovulation day would be 28-14= day 14
    If your menstrual cycle has 26 days, your ovulation day would be 26-14= day 12.
    For that of 30 days, ovulation day would be 30-14= day 16.
    You should know your probable ovulation day, because days around your ovulation day are your fertile period which are the best for sex in order to attain pregnancy.
  3. Knowing which days are fertile: now that your know the length of your menstrual cycle, and also know your ovulation day, we can now find out which days are your probable fertile days and which are your safe days. To do this;
    Remember that the sperm of the man can survive for up to 5 days in the woman’s body, waiting for the egg. While the egg can stay for up to 24 hours waiting for the sperm.
    To find your safe days,
    A. Count back 5 days from your probable ovulation day, and
    B. Count 2 days ahead of your probable ovulation day.
    This is including your ovulation day is a total of 8 days which represent your fertile days.
    Hence, for a;
    28 day cycle: Fertile days are days 9-16.
    26 day cycle: Fertile fays are days 7-14.
    30 day cycle: Fertile days are days 11-18.

Then count this days on a calendar and know the actual day that it falls on. E.g, if your day 1 is on May 4th, 2020. Your fertile day would start on 12th of May, and end on 20th of May. You should target having sex every 2 days during this period to increase your chances of fertilization & pregnancy.

If you find it difficult to mark your days on a calendar or to know the number of days, you can download a “Women’s Diary” application from google play store that can help you keep a check of these days.

We believe at this point, you have no more confusion on knowing your fertile days, and doing a proper family planning.
If you still have any confusion or question, please use the comment box below, and we would surely get back to you.


  • Obasi Chinedu

    Obasi Chinedu David attended the College of Medicine, University of Nigeria Teaching Hospital, in ituku-ozalla, Enugu state, Nigeria.

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