When can a woman ovulate
Right Time For Sex , When Do You Ovulate ?
When are you more likely to conceive?
We’re talking about the 'fertile window’ – the days in a woman’s menstrual cycle when pregnancy is possible. The ‘fertile window’ depends on the length of the menstrual cycle, which varies among women.
The ‘fertile window’ is the day an egg is released from the ovary (ovulation) and the five days beforehand. Having sex (intercourse) during this time gives you the best chance of getting pregnant.
Ovulation Calculator
What day did you your most recent period start?
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Your ovulation day
Most fertile time
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What is an ovulation calculator and how does it help you get pregnant?
This ovulation calculator or ovulation calendar can help you work out your most fertile time. These are the days you are most likely to get pregnant.
It can also estimate your due date if you do become pregnant during your next fertile days.
Others ways to help you work out when you're ovulating:
- Notice changes in vaginal mucus
A few days before ovulation, you may notice your vaginal mucus becomes clear, slick and slippery, and feels a bit like egg white.
This is a sign that ovulation is about to happen. It’s the best time to have sex, as sperm travel more easily in this kind of mucus.
- Use an ovulation predictor kit
You can use a predictor kit from a supermarket or pharmacy, to test your urine for signs of ovulation. If you start testing your urine a few days before the day you next expect to ovulate, a positive result means you are going to ovulate within the next 24 to 36 hours (one to two days).
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Facts about timing
Ovulation is when a mature egg is released from the ovary. The egg then moves down the fallopian tube where it can be fertilised. If sperm are in the fallopian tube when the egg is released, there is a good chance that the egg will be fertilised, creating an embryo, which can grow into a baby.
Pregnancy is technically only possible if you have sex during the five days before ovulation or on the day of ovulation. But the most fertile days are the three days leading up to and including ovulation. Having sex during this time gives you the best chance of getting pregnant.
By 12-24 hours after ovulation, a woman is no longer able to get pregnant during that menstrual cycle because the egg is no longer in the fallopian tube.
There’s almost no chance of getting pregnant if you have sex before or after the fertile window (but if you’re not trying to get pregnant, don’t rely on this – contraception is your best option!).
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How to know when you’re ovulating
Knowing when you ovulate can help you plan for sex at the right time and improve your chance of getting pregnant. You can keep track of your menstrual cycles on a chart, in a diary, or on a free period-tracker app on your smartphone.
To work out the length of your menstrual cycle, record the first day you start bleeding (first day of your period). This is day 1. The last day of your cycle is the day before your next period begins.
- What is a ‘menstrual cycle’ and a ‘period’?
Some people think the ‘menstrual cycle’ and a ‘period’ are the same thing.
A period is when you bleed (or menstruate).
A menstrual cycle starts on the day when a period starts (day 1) and ends the day before the next period. A cycle’s length is considered normal if it’s between 21 and 35 days. They can vary between women and from one cycle to the next.
- Working out your ‘average’ menstrual cycle length
If your menstrual cycles are different lengths (most women’s cycles are) you can work out your average cycle length.
The number of days in a woman’s menstrual cycle can vary month to month. Periods are not always regular. It can be useful to work out an ‘average’ cycle length, based on the length of three menstrual cycles, to estimate when you’re most likely to be ovulating.
If you add the number of days in three cycles and divide the total number by three, it gives you your average cycle length.
Example
Sarah tracked her last three menstrual cycles by counting the time from the first day of one period, to the day before the next period.
Cycle 1 was 28 days; Cycle 2 was 32 days; Cycle 3 was 27 days
28 + 32 + 27 = 87
87 divided by 3 = 29
So the average length of Sarah’s menstrual cycles is 29 days.
- Working out your most fertile days
When you know your average menstrual cycle length, you can work out when you ovulate.
Ovulation happens about 14 days before your period starts.
- If your average menstrual cycle is 28 days, you ovulate around day 14, and your most fertile days are days 12, 13 and 14.
- If your average menstrual cycle is 35 days ovulation happens around day 21 and your most fertile days are days 19,20 and 21.
- If you have shorter cycles, say 21 days, ovulation happens around day 7 and your most fertile days are days 5, 6 and 7.
Your most fertile days are the three days leading up to and including the day of ovulation.
Some women have very irregular cycles or find it difficult to work out an average cycle length. This can make it hard to work out when ovulation happens. If it’s all too hard, having sex every 2-3 days covers all bases and improves your chance of getting pregnant.
Myth busting
- MYTH
A woman can get pregnant any time of the month.
- FACT
A woman can only get pregnant on a few days during her menstrual cycle.
Why?
Because eggs and sperm only live for a short time:
- Sperm live for around five days.
- Eggs can only be fertilised for around 24 hours (one day) after being released from the ovary.
Eggs and sperm need to come together at the right time for fertilisation to happen to create an embryo.
Getting the timing right
If you're trying to get pregnant, timing is everything. Dr Karin Hammarberg explains how to work out when you are ovulating and the right time to have sex to improve your chance of pregnancy.
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What are the chances?
Having sex as close as possible to the time of ovulation increases the chance of pregnancy.
If a woman has sex six or more days before she ovulates, the chance she will get pregnant is virtually zero.
If she has sex five days before she ovulates, her probability of pregnancy is about 10 percent.
If she has sex on the day of ovulation, or the two days before, the chance of getting pregnant is around 30 percent.
These are average figures and depend on a woman’s age.
When does preconception health begin?
Professor Sarah Robertson, Director of Robinson Research Institute, University of Adelaide, highlights the key time before pregnancy that your health is most important to ensure your child has the best start to life.
How to know you are ovulating
Kerry Hampton, a registered nurse and fertility specialist, discusses the importance of fertility awareness, and how to determine your fertile window to improve your chances of conceiving.
- References
- American Society for Reproductive Medicine, Optimizing natural fertility, https://www.reproductivefacts.org/news-and-publications/patient-fact-sheets-and-booklets/documents/fact-sheets-and-info-booklets/optimizing-natural-fertility/
- Berglund Scherwitzl, et al. (2015). Identification and prediction of the fertile window using Natural Cycles. The European Journal of Contraception and Reproductive Health Care, 20(5), 403-408. doi:10.3109/13625187.2014.988210
- Ecochard, R., et al. (2015). Self-identification of the clinical fertile window and the ovulation period. Fertility and Sterility, 103(5), 1319-1325.e1313. doi: http://dx.doi.org/10.1016/j.fertnstert.2015.01.031
- Pfeifer, S., et al. (2017). Optimizing natural fertility: a committee opinion. Fertility and Sterility, 107(1), 52-58. doi: 10.1016/j.fertnstert.2016.09.029
- Stanford, J. B. (2015). Revisiting the fertile window. Fertility and Sterility, 103(5), 1152-1153. doi: http://dx.doi.org/10.1016/j.fertnstert.2015.02.015
- Stanford, et al. (2002). Timing intercourse to achieve pregnancy: current evidence. Obstetrics and Gynecology, 100(6), 1333-1341.
- Stephenson, J., et al. (2018). Before the beginning: nutrition and lifestyle in the preconception period and its importance for future health. The Lancet, 10.1016/S0140-6736(18)30311-8 doi: 10.1016/S0140-6736(18)30311-8
- Vélez, M. Pet al. (2015). Female exposure to phenols and phthalates and time to pregnancy: the Maternal-Infant Research on Environmental Chemicals (MIREC) Study. Fertility and Sterility. doi: 10.1016/j.fertnstert.2015.01.005
- Verón, G. L., et al. (2018). Impact of age, clinical conditions, and lifestyle on routine semen parameters and sperm kinematics. Fertility and Sterility, 110(1), 68-75.e64. https://doi.org/10.1016/j.fertnstert.2018.03.016
- Waylen, A. Let al. (2009). Effects of cigarette smoking upon clinical outcomes of assisted reproduction: a meta-analysis. Hum Reprod Update, 15(1), 31-44.
- Zenzes, M. T. (2000). Smoking and reproduction: gene damage to human gametes and embryos. Hum Reprod Update, 6(2), 122-131.
Page created on: 28/08/2018 | Last updated: 30/11/2022
Calculating, Timeline, Pain & Other Symptoms
What is ovulation?
Ovulation is a phase in the menstrual cycle when your ovary releases an egg (ovum). Once an egg leaves your ovary, it travels down your fallopian tube where it waits to be fertilized by sperm. On average, it happens on day 14 of a 28-day menstrual cycle.
Ovulation and your menstrual cycle
The process of ovulation begins when your hypothalamus (a part of your brain) releases gonadotropin-releasing hormone (GnRH). GnRH causes your pituitary gland (a gland in your brain) to secrete follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
Between days six and 14 of your menstrual cycle, FSH causes follicles (small sacs of fluid in your ovaries that contain a developing egg) in one ovary to begin to mature. During days 10 to 14 of the cycle, only one of the developing follicles forms a fully mature egg. Around day 14 in the menstrual cycle, a sudden surge in LH causes the ovary to release this egg. This is ovulation. After ovulation, the hormone progesterone rises which helps prepare your uterus for pregnancy.
Ovulation, conception and pregnancy
Once ovulation occurs, your egg travels through your fallopian tube. It’s in your fallopian tube that your egg meets sperm for fertilization. If conception occurs (sperm fertilizes your egg), the fertilized egg travels down to your uterus. After about a week, the fertilized egg (now a blastocyst) attaches to the lining of your uterus. This is called implantation. Release of the hormones estrogen and progesterone causes the endometrium to thicken, which provides the nutrients the blastocyst needs to grow and eventually develop into a baby. As cells continue to divide — some developing into the fetus, others forming the placenta — hormones signal your body that a baby is growing inside your uterus. This also signals your uterus to keep its lining, which prevents you from getting your period. Not getting a period is usually the first sign you’re pregnant.
When does ovulation occur?
In an average 28-day menstrual cycle, ovulation occurs about 14 days before the beginning of your next menstrual period. The exact timing varies — your cycle length may be longer or shorter. You may find it helpful to track your menstrual cycle using an app on your phone or a calendar. This can help you determine when ovulation is most likely to occur. Most people will have a period 14 to 16 days after ovulation, regardless of the length of their overall cycle.
How many hours does ovulation last?
An egg only survives 12 to 24 hours after ovulation. If sperm doesn’t’ fertilize the egg, your body reabsorbs it. Unlike your egg, sperm can survive for several days in your body.
How do I know I’m ovulating?
Pinpointing ovulation can be tricky. There are several methods people use to track their menstrual cycle and estimate when ovulation occurs. Since each method has its drawbacks, it’s always best to use more than one for the most accurate answer.
Menstrual cycle
Ovulation happens at around the midpoint of your cycle if you have a 28-day cycle (day 14). However, a “normal” cycle is anything between 21 and 35 days, so this means ovulation is unique to your menstrual cycle. Keep track of your cycle on paper or on an app on your phone for several months. Take note of any unusual symptoms. Most people ovulate 14 days before their period begins, regardless of cycle length.
Calendar method
People using the calendar method to predict ovulation, analyze six months of menstrual cycles to determine when they’re fertile. To calculate when you may be ovulating, you find your shortest cycle and your longest cycle in a six month period. You subtract 18 days from your shortest cycle and 11 days from your longest cycle. These two numbers give you the days in your cycle you’re most fertile. For example, if your cycle lengths are 31 and 18, your fertile time is day 10 to 20 of your cycle.
Cervical mucus
Cervical mucus is a vaginal fluid produced by your cervix. Your cervical mucus goes through stages during your menstrual cycle. Your cervical mucus is thick, white and dry before ovulation. Just before ovulation, your cervical mucus turns clear and slippery (like egg whites). This consistency makes it easy for sperm to swim up to meet your egg.
Basal body temperature
Your body temperature increases slightly during ovulation (typically about 0. 5 to 1 degree). Take your temperature every morning using a digital thermometer meant specifically for measuring basal body temperature. This method only works if you take your temperature before you get out of bed and before you eat/drink. Record your results for several months and note what day of your cycle a temperature increase occurs.
Ovulation kits
Ovulation kits work similarly to at-home pregnancy tests because you pee on an indicator strip in the comfort of your own home. They work by detecting LH (luteinizing hormone) in your pee. LH is the hormone that surges before ovulation. A positive result means you’re about to ovulate (usually within 36 hours).
What are the symptoms of ovulation?
Every person is different and not everyone has signs of ovulation. In those that do, the most common symptoms are:
- Tender breasts.
- Bloating.
- Minor pelvic or abdominal pain.
- Light bleeding or spotting.
- Changes in the position and firmness of your cervix.
- Increased sex drive.
- Heightened sense of smell, taste or sight.
- Mood changes.
- Appetite changes.
How many days during ovulation can you get pregnant?
Even though your egg only lives for 24 hours, sperm can live in your uterus for between three and five days. This means you can get pregnant from having sex from about five days before ovulation to one day after ovulation. If pregnancy is your goal, it’s better to have sperm already in your body when you ovulate. The highest probability of conception occurs when intercourse takes place one to two days before ovulation and on the day of ovulation.
Is pain during ovulation normal?
Yes, many people experience ovulation pain. Ovulation pain (or mittelschmerz) is cramping or pelvic pain that happens around ovulation. You typically feel the pain in your lower abdomen and pelvis, in the middle or on one side. Ovulation pain may happen when an egg bursts from a follicle (the sacs in your ovaries that contain eggs). It can even cause light bleeding.
Pain during the time of ovulation may also be caused by a medical condition, so it’s best to contact your healthcare provider to be sure the pain isn’t something more serious.
What happens if I’m not ovulating?
Certain health conditions or life events may affect ovulation or cause you to stop ovulating. Some of these are:
- Breastfeeding (chestfeeding) or hyperprolactinemia.
- Menopause.
- PCOS (polycystic ovary syndrome).
- Primary ovarian insufficiency.
- Amenorrhea from things like high or low body fat, excessive stress or fatigue or excessive exercise.
If your period is irregular or you go months without a period, you may have not be ovulating. Contact your healthcare provider if this is the case so they can rule out any serious conditions.
Do you still ovulate if you’re on birth control?
No, if you’re taking birth control pills or other hormonal contraception as directed, you shouldn’t ovulate. Keep in mind, this is only the case if you’re using pills, patches, IUDs or other devices exactly as prescribed. The hormones in birth control work by stopping ovulation and thickening cervical mucus (which makes it harder for sperm to swim).
Can you ovulate but not get your period?
Yes. You can ovulate but not get your “period.” Technically, if you’re ovulating regularly, you should also get your period regularly. However, it’s possible to get your period without actually ovulating and to ovulate but not have a true period.
Can medicine help you ovulate?
Yes, there are fertility medications to induce ovulation. Talk to your healthcare provider about your symptoms and goals, such as if you wish to become pregnant. They can work with you on the best treatment based on your condition.
A note from Cleveland Clinic
Ovulation is a process that occurs during your menstrual cycle. The exact timing of ovulation varies from person to person and even from cycle to cycle. Without ovulation, it’s hard for you to get pregnant or have regular menstrual periods. There are many methods available to help you predict ovulation. Knowing when you ovulate can help you either achieve a pregnancy or avoid a pregnancy. There are several health conditions that affect ovulation. Contact your healthcare provider if you’re concerned that you’re not ovulating.
All about ovulation. Frequently Asked Questions
1. Is the maturation of several eggs at the same time a rarity for a healthy woman?
Egg maturation is a complex process that depends on the hormonal activity of the body. It is known that the maturation of most rudimentary germ cells occurs in utero. Starting from adolescence, under the influence of pituitary hormones, cyclic changes occur in the ovaries. The fate of each follicle is under the control of the endocrine systems, from which subsequent events occur - the growth of follicles, the choice of the dominant (leading), egg maturation, ovulation and the formation of the corpus luteum. As a rule, in humans, 1 egg matures in a cycle. The maturation of multiple eggs is rare for women. Most often, this can be in a couple in whose family twins were born. Also, the maturation of several eggs occurs in ART programs (assisted reproductive technologies). During the programs, several eggs are grown and fertilized.
2. How does a woman's age affect ovulation? Is a cycle without ovulation normal?
A woman's age is an indisputable argument in assessing the functional state of a woman's reproductive system. To date, the main patterns of the processes of follicle growth, ovulation and the development of the corpus luteum have been determined, and they are associated, in particular, with the hormonal regulation of the body. With age, the number of follicles in a woman's ovary decreases and the quality of the eggs changes. The process of "aging of the ovaries" begins by the age of 30, and after 37 years, the number of follicles from which eggs mature sharply decreases. Although within the age, especially older reproductive age, there are individual characteristics due to human genetics. However, the age of loss of the ability to conceive and the age of loss of hormonal function by the ovaries, as a rule, do not coincide. Between the ages of 40 and 45, a woman loses the ability to conceive because there are few cycles with ovulation, but she can still have menstrual cycles and hormonal activity of the ovaries for another 10 years.
Anovulatory cycles are considered normal during the year when the menstrual function is established in adolescents, while taking contraceptives. For a short time, there may not be ovulation during stress, illness. Anovulatory cycles are also possible in healthy women (1-2 times a year). The constant absence of ovulation in the reproductive age is not the norm and requires consultation, examination, medical treatment, as it indicates a disease and the formation of infertility in a woman.
3. What diseases disrupt the maturation of the egg?
There are several groups of diseases that disrupt the maturation of the egg. Often several diseases are detected at the same time that affect ovulation and lead to infertility in a woman.
1. The psychological state of a woman (chronic stress).
2. Mental illness.
3. Genetic diseases.
4. Benign and malignant tumors of various organs and systems.
5. Diseases of organs such as the pituitary gland, thyroid gland, adrenal glands, pancreas, mammary glands, ovaries, which can cause changes in hormonal status
6. Inflammatory diseases, especially of the reproductive organs.
7. Obesity and other metabolic disorders.
4. Is measuring basal body temperature an indicative method? Can ovulation occur at a temperature below 37 *. Can the temperature rise and ovulation not occur?
Measurement of basal body temperature (BT) is a functional diagnostic test that allows you to assess the hormonal function of the body and indirectly determine the fertile phase of the menstrual cycle. The temperature is influenced by many factors of the physical and psychological state of a woman: sleep disturbance, disease, stress, sexual intercourse. In this regard, the change in BBT is not the main, but an auxiliary method for determining ovulation in a woman and the state of her hormonal background. The result of the measurements is entered into a special schedule. In the first half of the cycle, it is below 37*, the day before ovulation the temperature drops, and during ovulation it rises by 0.3 - 0.6* and stays at this level until the end of the cycle, for at least 12 days (within 37.0 - 37.4*). 2-3 days before the onset of menstruation, BBT begins to decline, reaching about 37 * by its beginning. The difference between the first phase and the second phase must be at least 0.4 - 0.5*. The perfect schedule is rare. Options for BT can be varied, and each feature indicates certain violations. As a rule, the difference between the average value of BT 1 and 2 phases is less than 0.4 * - the egg does not mature. A more detailed consultation on the results of BT and ovulation is given individually by a doctor in each specific situation. To establish ovulation, several parameters of a woman’s examination are analyzed at once: BT, ultrasound of the ovaries and uterus, blood hormones by phases of the menstrual cycle, as well as examination and questioning of the patient. A low temperature in both phases (for example, 36.0 - 36.5 *) while maintaining a difference of at least 0.4 * is also a normal individual phenomenon.
5. Can ovulation tests lie? Is a positive test always an indicator that ovulation has occurred?
Ovulation is the release of an egg from the ovary, which is ready for fertilization and is controlled by hormones. When the follicle reaches a certain size and functional activity, it breaks, through which the egg leaves the follicle. Between the process of preparing for ovulation and ovulation itself is about 36-48 hours. If the egg is fertilized, then by day 4 the embryo enters the uterus and implantation occurs. If fertilization does not occur, then the egg dies.
On average, ovulation occurs on the 14th day of the menstrual cycle (with a 28-day cycle). Deviation from the mean is observed quite often and is not a pathology.
Urine ovulation tests are based on the determination of luteinizing hormone (LH) in urine. Tests are single and multiple. The tests are not completely accurate. The reasons for false negative results for ovulation can be:
- different testing times;
- the amount of liquid drunk on the eve of testing;
- different test sensitivity;
- each woman's body produces a different amount of LH;
- if you test once a day with an irregular cycle, it is possible to miss ovulation.
Unfortunately, ovulation tests do not show ovulation, but LH levels over time.
An increase in LH levels is characteristic of the ovulation phase, but may be elevated with hormonal dysfunction, postmenopause, lean ovary syndrome, kidney disease, ovulation stimulation after hCG injections.
Therefore, relying only on tests for hormonal dysfunctions is not worth it. It is necessary to additionally use ultrasound to determine the presence and timing of ovulation.
Signs of ovulation
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OVULATION (from lat. ovum - egg) - release of a mature egg capable of fertilization from the ovarian follicle into the abdominal cavity; stage of the menstrual cycle (ovarian cycle). Ovulation in women of childbearing age occurs periodically (every 21-35 days). The frequency of ovulation is regulated by neurohumoral mechanisms, mainly gonadotropic hormones of the anterior pituitary gland and ovarian follicular hormone. Ovulation contributes to the accumulation of follicular fluid and thinning of the ovarian tissue, located above the protruding pole of the follicle. The rhythm of ovulation , which is constant for every woman, undergoes changes within 3 months after an abortion, within a year after childbirth, and also after 40 years, when the body is preparing for the premenopausal period. Stops ovulation with the onset of pregnancy and after the extinction of menstrual function. Establishing the term ovulation is important when choosing the most effective time for fertilization, artificial insemination and in vitro fertilization.
Signs of ovulation
Subjective signs of ovulation may be short-term pain in the lower abdomen. Objective signs of ovulation are an increase in vaginal mucus and a decrease in rectal (basal) temperature on day ovulation with an increase in it the next day, an increase in the content of progesterone in the blood plasma, etc. Violation of ovulation is due to dysfunction of the hypothalamic-pituitary-ovarian system and can be caused by inflammation of the genitals, dysfunction of the adrenal cortex or thyroid gland, systemic diseases, tumors of the pituitary gland and hypothalamus, stressful situations. Lack of ovulation at childbearing age (anovulation) is manifested by a violation of the rhythm of menstruation by the type of oligomenorrhea (menstruation lasting 1-2 days), amenorrhea, dysfunctional uterine bleeding. Absence ovulation (anovulation) is always the cause of a woman's infertility. Methods for restoring ovulation are determined by the cause that caused anovulation, and require an appointment with a gynecologist and special treatment.
Some women experience peak sexual arousal on days 90,003 of ovulation 90,004. However, the use of a physiological method of contraception against pregnancy, based on sexual abstinence during ovulation , is especially difficult for young spouses, whose frequency of sexual intercourse reaches a fairly high level. In addition, with strong love excitement and nervous stress, additional ovulation can occur (especially with episodic, irregular intercourse), and then not one, but two eggs mature in one menstrual cycle. This should be remembered when choosing one or another method of contraception.
As soon as every healthy girl aged 11-15 begins to menstruate, which is an indicator of her body's readiness for childbearing, then there are problems associated with counting the days of the menstrual cycle and the legitimate question why menstruation does not occur, or vice versa, why does not occur long-awaited pregnancy. This makes a woman think and wait all the time, be in the dark about what happens to her every month. And so every month for decades
Length of menstruation and cycle
Ideal menstruation lasts 3-5 days and repeats every 28 days. However, for some women, this cycle takes 19 days or even less, while for others it lasts from 35 to 45 days, which is a feature of their body, and not a violation of menstrual function. The duration of menstruation also, depending on the organism, can vary within a week. All this should not cause alarm in a woman, but a delay of more than two months, called opsometry or more than six months - amenorrhea, should alert the woman and make sure to find out the cause with a gynecologist.
Length of menstrual cycle
The menstrual cycle is a complex physiological process that continues in women up to 45-55 years. It is regulated by the so-called sex centers located in the middle part of the diencephalon - the hypothalamus. The changes that occur during the menstrual cycle are most pronounced in the uterus and ovaries. In the ovary, under the influence of hormones produced by the ovarian follicles, partly by the adrenal cortex and testes, the main follicle, which contains the egg, grows and matures. The mature follicle ruptures and the egg, together with the follicular fluid, enters the abdominal cavity, and then into the fallopian tube. The process of rupture of the follicle and the release of a mature (suitable for fertilization) egg from its cavity is called ovulation , which, with a 28-day cycle, occurs most often between the 13th and 15th days.
Corpus luteum, estrogen, progesterone
A corpus luteum forms at the site of the ruptured follicle. These morphological changes in the ovary are accompanied by the release of sex steroid hormones - estrogens and progesterone. Estrogens are secreted by the maturing follicle, and progesterone by the corpus luteum.
The release of estrogen has two maxima - during ovulation and during the period of maximum activity of the corpus luteum. So, for example, if the normal estrogen content is about 10 µg/l, then during ovulation it is about 50 µg/l, and during pregnancy, especially towards the end of it, the estrogen content in the blood increases to 70-80 µg/l per due to a sharp increase in the biosynthesis of estrogens in the placenta.
Together with progesterone, estrogens promote the implantation (introduction) of a fertilized egg, maintain pregnancy and promote childbirth. Estrogens play an important role in the regulation of many biochemical processes, are involved in carbohydrate metabolism, lipid distribution, stimulate the synthesis of amino acids, nucleic acids and proteins. Estrogens contribute to the deposition of calcium in bone tissue, delay the release of sodium, potassium, phosphorus and water from the body, that is, increase their concentration both in the blood and in electrolytes (urine, saliva, nasal secretions, tears) of the body.
The secretion of estrogens is controlled by the anterior pituitary gland and its genadotropic hormones: follicle-stimulating (FSH) and luteinizing (LH).
Under the influence of estrogens in the first phase of the menstrual cycle, called folliculin, regeneration occurs in the uterus, that is, the restoration and growth of its mucous membrane - the endometrium, the growth of glands that stretch in length and become convoluted. The mucous membrane of the uterus thickens 4-5 times. In the glands of the cervix, the secretion of mucous secretion increases, the cervical canal expands, and becomes easily passable for spermatozoa. In the mammary glands, the epithelium grows inside the milk ducts.
In the second phase, called luteal (from the Latin word luteus - yellow), under the influence of progesterone, the intensity of metabolic processes in the body decreases. The growth of the mucous membrane of the body of the uterus stops, it becomes loose, edematous, a secret appears in the glands, which creates favorable conditions for attaching a fertilized egg to the mucous membrane and developing the embryo. The glands stop secreting mucus, the cervical canal closes. In the mammary glands, from the overgrown epithelium of the end sections of the milk ducts, alveoli arise, capable of producing and secreting milk.
If pregnancy does not occur, the corpus luteum dies, the functional layer of the endometrium is rejected, and menstruation occurs. Monthly bleeding varies from three to seven days, the amount of blood lost is from 40 to 150 g.
It should be noted that different women have a noticeable difference in the timing of ovulation . And even for the same woman, the exact timing of the onset fluctuates in different months. In some women, cycles are characterized by exceptional irregularity. In other cases, cycles may be longer or shorter than the average - 14 days. In rare cases, it happens that in women with a very short cycle ovulation occurs around the end of the period of menstrual bleeding, but still, in most cases, ovulation occurs quite regularly.
If, for one reason or another, ovulation does not occur , the endometrial layer in the uterus is thrown out during menstruation. If the fusion of the egg and sperm has occurred, then the cytoplasm of the egg begins to vibrate very strongly, as if the egg is experiencing an orgasm. Sperm penetration is the final stages of egg maturation. All that remains of a spermatozoon is its nucleus, where 23 chromosomes are densely packed (half the set of a normal cell). The sperm nucleus is now rapidly approaching the egg nucleus, which also contains 23 chromosomes. The two cores are slowly touching. Their shells dissolve and they merge, as a result of which they are divided into pairs and form 46 chromosomes. Of the 23 chromosomes of the sperm, 22 are completely analogous to the chromosomes of the egg. They determine all the physical characteristics of a person except gender. In the remaining pair from the egg there is always an X chromosome, and from the sperm there can be an X or Y chromosome. Thus, if there are 2 XX chromosomes in this set, then a girl will be born, if XY, then a boy.
Studies conducted at the National Institute of Environmental Medical Problems (North Carolina) showed that the time of conception in relation to the time of onset of ovulation depends not only on the actual conception of a child, but also on its gender.
The probability of conception is maximum on day of ovulation and is estimated at about 33%. A high probability is also noted on the day before ovulation - 31%, two days before it - 27%. Five days before ovulation the probability of conception is estimated to be 10% four days before ovulation - 14% and three days - 16%. Six days before ovulation and the day after ovulation, the probability of conception during sexual intercourse is very small.
Considering that the average “lifespan” of spermatozoa is 2-3 days (in rare cases it reaches 5-7 days), and the female egg remains viable for about 12-24 hours, then the maximum duration of the “dangerous” period is 6- 9days and the “dangerous” period corresponds to the phase of slow rise (6-7 days) and rapid decline (1-2 days) before and after the day of ovulation , respectively. Ovulation , as noted above, divides the menstrual cycle into two phases: the follicle maturation phase, which, with an average cycle duration of 10-16 days, and the luteal phase (corpus luteum phase), which is stable, independent of the duration of the menstrual cycle and is 12-16 days. The phase of the corpus luteum is referred to as the period of absolute infertility, it begins 1-2 days after ovulation and ends with the onset of a new menstruation.
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