30 January 2019

When are women most fertile?

By the Editorial Comitee IVI Blog

Whether you are a woman taking precautions to prevent pregnancy or someone hoping to conceive, the question of fertility seems to be always there in the background. The issue of when a female is most fertile has two aspects. Firstly, there is the point in your monthly menstrual cycle when you are most likely to conceive. This is where a fertility calendar or ovulation calculator can help with the arithmetic. The second aspect of the question is about biological age and the stage of life at which women are most fertile. In our article we look at the monthly cycle, which are the most fertile days during that cycle and the various means of monitoring and predicting ovulation. This allows times of maximum fertility to be predicted with some accuracy. Secondly, we look at the stages of fertility in the different times of a woman’s life and the effect these will have on her ability to conceive.

When is a female most fertile? What the menstrual cycle reveals

Generally speaking you are at your most fertile a day or two either side of ovulation. This is when an egg is released from your ovaries. You can calculate with a reasonable degree of accuracy when ovulation will take place, especially if your cycle is regular, at somewhere between 24 and 35 days. Count the start of your period as day one of your cycle and the day before your next period as the end of the cycle. Ovulation normally takes place 12-16 days before the start of your next period. Thus, if you have a regular 28-day cycle (and of course many women do not) then the figure remains the same: ovulation takes place on Day 12-Day 16. However the fertile time is not restricted to those few days. Remember you could get pregnant if you have unprotected sex at any point during the week before ovulation, as sperm can live inside a woman’s body for up to seven days.

Fertility specialists usually advise that if you’re hoping to get pregnant, you don’t need to specifically plan sex around this time, since it can be difficult to work out the exact day of ovulation, and trying to have sex to a schedule can cause completely avoidable stress and anxiety. For the best chance of getting pregnant, so long as there are no underlying fertility problems, have sex every 2-3 days throughout your cycle. Even so, for some women, whether the urge to predict fertile days is irresistible or whether they suspect an underlying problem, there are several ways that can help with fertility prediction. These are fertility calendars, ovulation predictor kits and self-monitoring for signs of ovulation.


Fertility calendar

This can take the form of an old-fashioned pen and paper, a spreadsheet or one of the many online calendars available. They are also known as ovulation calendars or ovulation calculators. They all do the same thing, which is to track the dates of your menstrual cycle and using the 12 to 16-day calculation set out above, to identify the days on which the chances of conception are highest.


Ovulation predictor kits

These are test kits which measure levels of luteinising hormone (LH) in your urine. The critical measurement is a surge in the level of LH which happens as part of your cycle a couple of days before ovulation. This is therefore prime conception time. There are also tests which aim to measure the same hormone surge, but using a saliva sample. In these tests, saliva is observed for a fern-like pattern when dried on glass. The urine version of the test is overall more accurate.


Self-monitoring for signs of impending ovulation

Self-monitoring involves taking your temperature every morning after waking up, plus monitoring the quality and consistency of vaginal mucus secretions. This needs to continue for a few months for patterns to be recognised. It is the least reliable of the methods because there can be many differing causes of temperature fluctuations and in reality, many people find the routine tiresome and difficult to sustain.


If you are still not pregnant, when should you seek help?

If, in spite of your best efforts to understand your menstrual cycle and predict your fertile times, you have not conceived after a year –or after 6 months if you are older than 35–, it could be time to seek advice and assistance. At IVI we will be very happy to discuss your individual situation and run some tests that will determine whether or not there is a fertility problem with you and or your partner. One of the most basic assisted fertility procedures is designed to maximise, with a little intervention, the potential for sperm and egg to meet, which is what you have been aiming for all along. This is the procedure known as artificial insemination.

Artificial insemination using semen from the male partner can be recommended for couples in which the woman has ovulation problems, as well as cases where there is an abnormality of the cervix, the man has slight or moderate defects in his semen, or where the reasons for infertility are unknown. You can take a look at the video on our IVI YouTube channel to explain more about this. Here’s what happens, step by step.


Assisted reproduction at its simplest: Artificial Insemination


Ovarian stimulation and ovulation induction

This procedure is necessary to increase the chances of success, as a woman only produces a single ovum in each natural menstrual cycle. In addition, it is essential that at least one of the fallopian tubes is permeable and that the man’s semen contains a minimum concentration of motile spermatozoa. This phase consists of stimulating the ovary so that it naturally produces more ova, and it lasts around 10-12 days. During treatment, ultrasound scans and blood tests determine whether there is normal growth and development of the follicles. When the follicles have reached an adequate size and number, artificial insemination is scheduled for around 36 hours after an injection of hCG to induce oocyte maturation and ovulation.

Preparation of the semen

Semen preparation in artificial insemination consists of selecting and concentrating the spermatozoa with the best motility. Preparation techniques allow the elimination of unsuitable spermatozoa, and therefore the quality of the sample which is to be used for insemination is optimised.


The process of artificial insemination is carried out at an IVI assisted reproduction clinic following ovulation induction. Preparation of the semen sample takes place two hours beforehand. A speculum is put in place, which is no more uncomfortable than having a smear test, following which the cannula is passed through the cervix, enabling the sample to be introduced into the uterus.


The bigger picture: life stages affecting female fertility

The other aspect involved in determining when a woman is at her most fertile relates simply to age. It’s well known that fertility peaks during a woman’s 20s and starts to decline after the age of 30; after 35, natural conception rates start to drop sharply. However, in today’s society many women, for absolutely understandable financial and social reasons, choose to delay parenthood until their early thirties. Thus we have the ironic situation where many women who have long sought to prevent pregnancy in their younger years reach a point where they find themselves looking for ways to promote their chances of conception.

Many young women now choose to take action to avoid this situation by opting for treatment for the preservation of fertility through the vitrification of oocytes. In this way there’s a good chance of being able to delay motherhood until the time is right. If this rings a bell with you or you would like to know more about what’s involved, have a look at the oocyte vitrification video on our IVI YouTube channel. We would also encourage anyone who would like to know more about the work that we do at IVI and the possibilities of assisted reproduction treatments, to browse our website for the most up-to-date facts, figures and articles about new developments. 

Relax – don’t worry

Have you heard this piece of advice before? We feel sure you have. But it really is a worthwhile exercise to pay attention to your stress levels, practice yoga or knitting or meditation; whatever helps you individually. Most women who are trying to get pregnant do achieve their aim within a year or so. But if you’re really concerned that you and or your partner may have an underlying fertility problem, do contact IVI. There are no strings and no obligation, and it can be a real help to talk over your situation and your feelings with someone who understands. You can contact us by phone on 08 000 850 035 from the UK, or on +34 960 451 185 from all other countries. You can also use our online contact form and a specialist adviser will be in touch.

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  • Michelle Balo says:

    Hi! May i ask if you ship sperm to Asia? I am from the Philippines and would like to avail of your sperm bank services. Thank you

  • IVI says:

    Dear Michelle, I’m afraid we don’t sell sperm.

IVI treats its database confidentially and does not share it with other companies.

Thank you for contacting us
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