When Is A Girl Most Fertile?

To increase the chances of getting pregnant, women can determine the time of month when they are most fertile. How to calculate your ovulation period? What are the different methods to know your fertility period? Doctissimo takes stock with you.

Many couples do not have a clear idea of how ovulation works. Most parents do not even know exactly when they conceived their child. Yet, there are many ways to know when in the cycle the woman is the most fertile! Doctissimo even offers to calculate your ovulation date with its online tool and thus determine the fertility period.

Menstrual cycle, ovulation … How does it work?

The menstrual cycle is a natural hormonal process whose function is to ensure reproduction . It lasts an average of 28 days in a woman. It is divided into two periods separated by ovulation that takes place around the 14th day . The first period is the " follicular phase ", during which the rules arrive (on the first day of the cycle). The purpose of this phase is to mature an ovum that will be released by the ovary on the 14th day . This is where fertilization takes place.

The second part, called " luteal phase ", has the role of preparing the arrival of the fertilized egg in the uterus. If there is no fertilization, the rules come and a new cycle begins.

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Ovulation is the term used to define the release of an ovum (usually one but sometimes more) by the ovary. A child's conception occurs when a sperm fertilizes the egg. While sperm can survive for several days in the female genital tract, the egg only survives 24 hours after ovulation . This therefore limits the probability of fertilization.

How to determine your fertility period?

To increase the chances of becoming pregnant, women can learn about their fertility period, the length of time sperm can survive in the female reproductive tract before ovulation and fertilization occur.

During a cycle, the fertility period lasts 5 to 7 days: four to five days before the date of ovulation and one to two days later . To calculate its fertility period, several methods are used:

The calendar

You can simply postpone the date of the rules on a calendar and deduct 14 days from the cycle time (14 days before the next rules). You will be able to know your date of ovulation and determine your period of fertility.

The temperature curve

The temperature curve makes it possible to determine at what moment of its cycle a woman ovulates. To plot a thermal curve, simply take its temperature every morning and note the results on a grid, usually for three months. The results of this curve provide information on the precise timing of ovulation . The curve can be completed with other events: menstruation, fever diseases, intercourse, etc.

Cervical mucus

The cervix secretes mucus (mucus) that protects the woman's body from sperm, bacteria and other micro-organisms. For a few days a month, the consistency of the mucus changes to allow the sperm to reach the tubes . By monitoring these changes, it is possible to determine the fertile period . Just insert one or two fingers into the vagina and collect the secretions in contact with the cervix.

Right after the menses, there is no mucus . In the following week, the cervical secretions are viscous and sticky. As ovulation approaches, the mucus becomes creamy , lighter and can be stretched between two fingers without breaking down . This corresponds to the peak of fertility where the mucus allows the spermatozoa to pass.

It should be kept in mind that different factors can alter cervical secretions : sexual arousal, the presence of sperm, the use of lubricants, the use of an antihistamine, a vaginal infection …

The ovulation test

Luteenizing hormone (LH) peaks within 24 to 36 hours before a woman ovulates . Thus, by measuring the level of LH every day, it is possible to detect the peak and give a daily information on the fertility period . The test is urinary or salivary, it is available in pharmacies and it can easily be done at home. For more reliable results, it is advisable to make it every morning at the same time.

When the test is positive, it is imperative to have sex as soon as possible to have a chance to get pregnant.

Determining the fertility period is not always easy

Because of various factors (hormonal, environmental, psychological, infection, etc.), the menstrual cycle can vary from one woman to another : it can be longer or shorter (between 21 and 35 days) or irregular . It is not always easy to determine the fertile period of a woman.

In addition, the fertile period remains quite unpredictable even with regular cycles : a study published by the US National Institute of Environmental Health Sciences and conducted on 696 cycles shows that only 30% of women have a fertility window between 10 and Day 17. Most patients begin their fertile period earlier and others much later.

A woman under 35 must see a doctor after one year of unsuccessful attempts to get pregnant . A woman over 35 after six months.


- "Understanding pregnancy", Ameli.fr, 2018.

- National Institute of Environmental Health Sciences (NIEHS).