The Big O
During each monthly cycle, healthy couples in their 20s or early 30s who aren't using birth control have a 20 percent chance of getting pregnant. And that's a surprisingly high percentage considering that you can conceive only around the time of ovulation — a small window of opportunity each month (usually about 12 to 24 hours) during which the egg is viable, or open for the business of fertilization. Doesn't sound like much of an opening?
Consider, then, that sperm is able to live to fertilize for a lot longer than an egg is willing to hang out, anywhere from three to six days. Which means that even if you have sex a few days before ovulation, there may be plenty of sperm still around to greet the egg when it emerges. And, remember, it only takes one sperm to make a baby. Of course, having sex the day you ovulate would be ideal. After ovulation, that window tends to slam shut till the next cycle. Clearly, knowing when the Big O occurs is key to know when to do the Baby Dance.
Ovulation is one part of the female menstrual cycle whereby a mature ovarian follicle (part of the ovary) discharges an egg (also known as an ovum, oocyte, or female gamete). It is during this process that the egg travels down the fallopian tube where it may be met by a sperm and become fertilized.
Ovulation is controlled by a part of the brain called the hypothalamus, which sends signals that instruct the anterior lobe and pituitary gland to secrete luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
The process usually occurs between the 10th and 19th day into the menstrual cycle, and this is the time where humans are most fertile.
What are the phases of ovulation?
The entire ovulation phase is defined by a period of elevated hormones during the menstrual cycle. The process itself can be informally divided into three phases:
Periovulatory (follicular phase): a layer of cells around the ovum begins to mucify (become more mucous-like) and expand, and the uterus lining begins to thicken.
Ovulatory (ovulation phase): enzymes are secreted and form a hole (or stigma) that the ovum and its network of cells use to exit the follicle and eventually enter the fallopian tube. This is the period of fertility and usually lasts from 24 to 48 hours.
Postovulatory (luteal phase): a hormone called LH or luteinizing hormone is secreted. A fertilized egg will be implanted into the womb, while an unfertilized egg slowly stops producing hormones. In addition, the lining of the uterus begins to break down and prepares to exit the body during menses.
When does ovulation occur?
A woman's menstrual cycle lasts between 28 and 32 days on average. The beginning of each cycle is considered to be the first day of her menstrual period (menses). Ovulation itself generally occurs between day 10 and day 19 of the menstrual cycle, or 12 to 16 days before the next period is due. Young women will begin to menstruate - a time referred to as menarche - between the ages of 9-15, and during this time will ovulate and be able to become pregnant.
Ovulation typically stops after menopause around the age of 51. Ovulation still occurs during the time leading up to menopause, however, which is referred to as peri-menopause.
How can ovulation be detected?
Ovulation may be detected by the effect it can have on a woman's body temperature. There are several indications that a woman is ovulating. During ovulation, the cervical mucus increases in volume and becomes thicker due to increased estrogen levels. It is often said that the cervical mucus resembles egg whites at a woman's most fertile point.
Ovulation may also lead to a 0.4 to 1.0 degree increase in body temperature. This is driven by the hormone progesterone that is secreted when an egg is released. Women are generally most fertile for two to three days before the temperature achieves its maximum.
Other ways to detect ovulation are:
Check the calendar: Ovulation most often occurs halfway through your menstrual cycle — the average cycle lasts 28 days, counting from the first day of one period (day one) to the first day of the next period. But as with everything pregnancy-related, there's a wide range of normal here (anywhere from 23 to 35 days), and your own cycle may vary slightly from month to month. By keeping a menstrual calendar for a few months, you can get an idea of what's normal for you — tools like an ovulation predictor can help you pin down the date. If your periods are irregular, you'll need to be even more alert for other signs of ovulation.
Listen to your body: If you're like 20 percent of women, your body will send you a memo when it's ovulating, in the form of a twinge of pain or a series of cramps in your lower abdominal area (usually localized to one side — the side you're ovulating from). Called mittelschmerz — German for "middle pain" — it may last between a few minutes and a few hours. This monthly reminder of fertility is thought to be the result of the maturation or release of an egg from an ovary. Pay close attention, and you may be more likely to get the message.
Chart your temperature: That is, your basal body temperature, or BBT. Taken with a special thermometer (yes, you guessed it, a basal body thermometer), your BBT is the baseline reading you get first thing in the morning, after at least three to five hours of sleep and before you get out of bed, talk, or even sit up. Your BBT changes throughout your cycle as fluctuations in hormone levels occur. During the first half of your cycle, estrogen dominates. During the second half of your cycle (once ovulation has occurred), there is a surge in progesterone. Progesterone increases your body temperature as it gets your uterus ready for a fertilized, implantable egg. Which means that in the first half of the month, your temperature will be lower than it is in the second half of the month, after ovulation.
Confused? Here's the bottom line: Your BBT will reach its lowest point at ovulation and then rise immediately and dramatically (about a half a degree) as soon as ovulation occurs. Keep in mind that charting your BBT for one month will not enable you to predict the day you ovulate but rather give you evidence of ovulation after it has occurred. Charting your BBT over a few months, however, will help you to see a pattern to your cycles, enabling you to predict when ovulation will occur in future months — and when to hop into bed accordingly.
Get to know your cervix: Ovulation isn't an entirely hidden process. As your body senses the hormone shifts that indicate an egg is about to be released from the ovary, it begins to ready itself for the incoming hordes of sperm and give the egg its best chance of getting fertilized. One detectable sign of oncoming ovulation is the position of the cervix itself. During the beginning of a cycle, your cervix — that neck-like passage between your vagina and uterus that has to stretch during birth to accommodate your baby's head — is low, hard, and closed. But as ovulation approaches, it pulls back up, softens a bit, and opens just a little, to let the sperm through on their way to their target. Some women can easily feel these changes, while others have a tougher time. Check your cervix daily, using one or two fingers, and keep a chart of your observations. The other cervical sign you can watch for is the appearance, increase in quantity, and change in consistency of cervical mucus (the stuff that gets your underwear all sticky). Its more noble purpose is to carry the sperm to the ovum deep inside you.
After your period ends, you'll have a dry spell, literally; you shouldn't expect much, if any, cervical mucus. As the cycle proceeds, you'll notice an increase in the amount of mucus with an often white or cloudy appearance — and if you try to stretch it between your fingers, it'll break apart. As you get closer to ovulation, this mucus becomes even more copious, but now it's thinner, clearer, and has a slippery consistency similar to an egg white. If you try to stretch it between your fingers, you'll be able to pull it into a string a few inches long before it breaks. (How's that for fun in the bathroom?) This is yet another sign of impending ovulation — as well as a sign that it's time to get out of the bathroom and get busy in the bedroom. Once ovulation occurs, you may either become dry again or develop a thicker discharge. Put together with cervical position and BBT on a single chart, cervical mucus can be an extremely useful (if slightly messy) tool in pinpointing the day on which you are most likely to ovulate — and it does so in plenty of time for you to do something about it.
Buy an ovulation predictor kit: Don't want to mess around with mucus? You don't have to these days. Ovulation predictor kits (OPKs) are able to pinpoint your date of ovulation 12 to 24 hours in advance by looking at levels of luteinizing hormone, or LH, which is the last of the hormones to hit its peak before ovulation actually occurs. All you have to do is pee on a stick and wait for the indicator to tell you whether you're about to ovulate.
Another option is a saliva test, which takes a peek at levels of estrogen in your saliva as ovulation nears. When you're ovulating, a look at your saliva under the test's eyepiece will reveal a microscopic pattern that resembles the leaves of a fern plant or frost on a windowpane. Not all women get a good "fern", but this test, which is reusable, can be cheaper than those sticks you have to pee on. There are also devices that detect the numerous salts (chloride, sodium, potassium) in a woman's sweat, which change during different times of the month. Called the chloride ion surge, this shift happens even before the estrogen and the LH surge, so these tests give a woman a four-day warning of when she may be ovulating, versus the 12-to-24-hour one that the standard pee-on-a-stick OPKs provide. The key to success in using this latest technology is to make sure to get an accurate baseline of your ion levels (currently, there's a device on the market that needs to be worn on the wrist for at least six continuous hours to get a proper baseline). No OPK can guarantee that you will get pregnant or that you're actually ovulating; they can only indicate when ovulation may be occurring. So no matter which device or method you choose, patience and persistence are key. Just don't forget to put together a candlelit dinner, draw a warm bubble bath, or plan a romantic weekend getaway — whatever it is that puts you and your partner in a baby-making mood.
What is an ovulation calendar?
An ovulation calendar is designed to help a woman predict when she will be most fertile. Several web apps exist that assist this process by asking questions, such as, when the beginning of the last menstrual cycle (period) was and how long the menstrual cycle generally lasts. Some calendars also request the length of the luteal phase (the day after ovulation to the end of the monthly cycle). It is generally useful for women to record or chart menstrual information so that it is available for entering into the calendar program.
Ovulation disorders
Infertility can be caused by a multitude of factors, one of which being disorders that affect a woman's ability to ovulate. These disorders include:
Polycystic ovarian syndrome (PCOS)
Hypothalamic dysfunction
Premature ovarian insufficiency
Excess prolactin.
A number of disorders that affect ovulation, such as polycystic ovarian syndrome, can lead to infertility. In cases of PCOS, women experience a variety of symptoms due to hormonal changes and imbalances. These imbalances lead to disruption in ovulation, as well as insulin resistance, obesity, abnormal hair growth and acne. PCOS is the leading cause of infertility in women.
Hypothalamic dysfunction is most evident in women who experience menstrual irregularities or amenorrhea (no menses), due to disruption in the production of the hormones responsible for ovulation - follicle-stimulating hormone (FSH) and luteinizing hormone. Causes of hypothalamic dysfunction include excessive physical or emotional stress, extreme body weight or substantial changes in weight (gains or losses).
Premature ovarian insufficiency (premature cessation of egg production) can be caused by autoimmune diseases, genetic abnormalities or environmental toxins. Women affected by this condition are typically under the age of 40, and additionally experience a decrease in their estrogen levels.
In certain situations, such as medication intake or a pituitary gland abnormality, women can produce excessive amounts of prolactin that in turn causes a reduction in estrogen production. Excess prolactin is a less common cause of ovulatory dysfunction.
Ovulation induction
Ovulation can be induced with the use of medication called fertility drugs. These medications are known to regulate, induce or trigger ovulation for a variety of reasons. To treat anovulation - cessation of ovulation - doctors may prescribe certain medications to aid in egg production and release and include:
Clomiphene citrate (Clomid, Serophene): this oral medication increases pituitary secretion of FSH and LH, causing stimulation of ovarian follicles.
Human menopausal gonadotropin or hMG (Repronex, Menopur) and FSH (Gonal-F, Follistim AQ, Bravelle): these injectable medications are known as gonadotropins and stimulate the ovary to produce several eggs for ovulation. The medication human chorionic gonadotropin (Ovidrel, Pregnyl) matures eggs and subsequently triggers them to be released during ovulation.
Metformin (Glucophage): this medication is typically used in women with PCOS to treat insulin resistance that increases the chances of ovulation.
Letrozole (Femara): this medication is an aromatase inhibitor and acts like the drug clomiphene, although it is not used as frequently due to the lack of information on its effect on early pregnancy.
Bromocriptine (Parlodel, Cycloset): this medication is used in cases of high prolactin levels interfering with ovulation.
Consider, then, that sperm is able to live to fertilize for a lot longer than an egg is willing to hang out, anywhere from three to six days. Which means that even if you have sex a few days before ovulation, there may be plenty of sperm still around to greet the egg when it emerges. And, remember, it only takes one sperm to make a baby. Of course, having sex the day you ovulate would be ideal. After ovulation, that window tends to slam shut till the next cycle. Clearly, knowing when the Big O occurs is key to know when to do the Baby Dance.
Ovulation is one part of the female menstrual cycle whereby a mature ovarian follicle (part of the ovary) discharges an egg (also known as an ovum, oocyte, or female gamete). It is during this process that the egg travels down the fallopian tube where it may be met by a sperm and become fertilized.
Ovulation is controlled by a part of the brain called the hypothalamus, which sends signals that instruct the anterior lobe and pituitary gland to secrete luteinizing hormone (LH) and follicle-stimulating hormone (FSH).
The process usually occurs between the 10th and 19th day into the menstrual cycle, and this is the time where humans are most fertile.
What are the phases of ovulation?
The entire ovulation phase is defined by a period of elevated hormones during the menstrual cycle. The process itself can be informally divided into three phases:
Periovulatory (follicular phase): a layer of cells around the ovum begins to mucify (become more mucous-like) and expand, and the uterus lining begins to thicken.
Ovulatory (ovulation phase): enzymes are secreted and form a hole (or stigma) that the ovum and its network of cells use to exit the follicle and eventually enter the fallopian tube. This is the period of fertility and usually lasts from 24 to 48 hours.
Postovulatory (luteal phase): a hormone called LH or luteinizing hormone is secreted. A fertilized egg will be implanted into the womb, while an unfertilized egg slowly stops producing hormones. In addition, the lining of the uterus begins to break down and prepares to exit the body during menses.
When does ovulation occur?
A woman's menstrual cycle lasts between 28 and 32 days on average. The beginning of each cycle is considered to be the first day of her menstrual period (menses). Ovulation itself generally occurs between day 10 and day 19 of the menstrual cycle, or 12 to 16 days before the next period is due. Young women will begin to menstruate - a time referred to as menarche - between the ages of 9-15, and during this time will ovulate and be able to become pregnant.
Ovulation typically stops after menopause around the age of 51. Ovulation still occurs during the time leading up to menopause, however, which is referred to as peri-menopause.
How can ovulation be detected?
Ovulation may be detected by the effect it can have on a woman's body temperature. There are several indications that a woman is ovulating. During ovulation, the cervical mucus increases in volume and becomes thicker due to increased estrogen levels. It is often said that the cervical mucus resembles egg whites at a woman's most fertile point.
Ovulation may also lead to a 0.4 to 1.0 degree increase in body temperature. This is driven by the hormone progesterone that is secreted when an egg is released. Women are generally most fertile for two to three days before the temperature achieves its maximum.
Other ways to detect ovulation are:
Check the calendar: Ovulation most often occurs halfway through your menstrual cycle — the average cycle lasts 28 days, counting from the first day of one period (day one) to the first day of the next period. But as with everything pregnancy-related, there's a wide range of normal here (anywhere from 23 to 35 days), and your own cycle may vary slightly from month to month. By keeping a menstrual calendar for a few months, you can get an idea of what's normal for you — tools like an ovulation predictor can help you pin down the date. If your periods are irregular, you'll need to be even more alert for other signs of ovulation.
Listen to your body: If you're like 20 percent of women, your body will send you a memo when it's ovulating, in the form of a twinge of pain or a series of cramps in your lower abdominal area (usually localized to one side — the side you're ovulating from). Called mittelschmerz — German for "middle pain" — it may last between a few minutes and a few hours. This monthly reminder of fertility is thought to be the result of the maturation or release of an egg from an ovary. Pay close attention, and you may be more likely to get the message.
Chart your temperature: That is, your basal body temperature, or BBT. Taken with a special thermometer (yes, you guessed it, a basal body thermometer), your BBT is the baseline reading you get first thing in the morning, after at least three to five hours of sleep and before you get out of bed, talk, or even sit up. Your BBT changes throughout your cycle as fluctuations in hormone levels occur. During the first half of your cycle, estrogen dominates. During the second half of your cycle (once ovulation has occurred), there is a surge in progesterone. Progesterone increases your body temperature as it gets your uterus ready for a fertilized, implantable egg. Which means that in the first half of the month, your temperature will be lower than it is in the second half of the month, after ovulation.
Confused? Here's the bottom line: Your BBT will reach its lowest point at ovulation and then rise immediately and dramatically (about a half a degree) as soon as ovulation occurs. Keep in mind that charting your BBT for one month will not enable you to predict the day you ovulate but rather give you evidence of ovulation after it has occurred. Charting your BBT over a few months, however, will help you to see a pattern to your cycles, enabling you to predict when ovulation will occur in future months — and when to hop into bed accordingly.
Get to know your cervix: Ovulation isn't an entirely hidden process. As your body senses the hormone shifts that indicate an egg is about to be released from the ovary, it begins to ready itself for the incoming hordes of sperm and give the egg its best chance of getting fertilized. One detectable sign of oncoming ovulation is the position of the cervix itself. During the beginning of a cycle, your cervix — that neck-like passage between your vagina and uterus that has to stretch during birth to accommodate your baby's head — is low, hard, and closed. But as ovulation approaches, it pulls back up, softens a bit, and opens just a little, to let the sperm through on their way to their target. Some women can easily feel these changes, while others have a tougher time. Check your cervix daily, using one or two fingers, and keep a chart of your observations. The other cervical sign you can watch for is the appearance, increase in quantity, and change in consistency of cervical mucus (the stuff that gets your underwear all sticky). Its more noble purpose is to carry the sperm to the ovum deep inside you.
After your period ends, you'll have a dry spell, literally; you shouldn't expect much, if any, cervical mucus. As the cycle proceeds, you'll notice an increase in the amount of mucus with an often white or cloudy appearance — and if you try to stretch it between your fingers, it'll break apart. As you get closer to ovulation, this mucus becomes even more copious, but now it's thinner, clearer, and has a slippery consistency similar to an egg white. If you try to stretch it between your fingers, you'll be able to pull it into a string a few inches long before it breaks. (How's that for fun in the bathroom?) This is yet another sign of impending ovulation — as well as a sign that it's time to get out of the bathroom and get busy in the bedroom. Once ovulation occurs, you may either become dry again or develop a thicker discharge. Put together with cervical position and BBT on a single chart, cervical mucus can be an extremely useful (if slightly messy) tool in pinpointing the day on which you are most likely to ovulate — and it does so in plenty of time for you to do something about it.
Buy an ovulation predictor kit: Don't want to mess around with mucus? You don't have to these days. Ovulation predictor kits (OPKs) are able to pinpoint your date of ovulation 12 to 24 hours in advance by looking at levels of luteinizing hormone, or LH, which is the last of the hormones to hit its peak before ovulation actually occurs. All you have to do is pee on a stick and wait for the indicator to tell you whether you're about to ovulate.
Another option is a saliva test, which takes a peek at levels of estrogen in your saliva as ovulation nears. When you're ovulating, a look at your saliva under the test's eyepiece will reveal a microscopic pattern that resembles the leaves of a fern plant or frost on a windowpane. Not all women get a good "fern", but this test, which is reusable, can be cheaper than those sticks you have to pee on. There are also devices that detect the numerous salts (chloride, sodium, potassium) in a woman's sweat, which change during different times of the month. Called the chloride ion surge, this shift happens even before the estrogen and the LH surge, so these tests give a woman a four-day warning of when she may be ovulating, versus the 12-to-24-hour one that the standard pee-on-a-stick OPKs provide. The key to success in using this latest technology is to make sure to get an accurate baseline of your ion levels (currently, there's a device on the market that needs to be worn on the wrist for at least six continuous hours to get a proper baseline). No OPK can guarantee that you will get pregnant or that you're actually ovulating; they can only indicate when ovulation may be occurring. So no matter which device or method you choose, patience and persistence are key. Just don't forget to put together a candlelit dinner, draw a warm bubble bath, or plan a romantic weekend getaway — whatever it is that puts you and your partner in a baby-making mood.
What is an ovulation calendar?
An ovulation calendar is designed to help a woman predict when she will be most fertile. Several web apps exist that assist this process by asking questions, such as, when the beginning of the last menstrual cycle (period) was and how long the menstrual cycle generally lasts. Some calendars also request the length of the luteal phase (the day after ovulation to the end of the monthly cycle). It is generally useful for women to record or chart menstrual information so that it is available for entering into the calendar program.
Ovulation disorders
Infertility can be caused by a multitude of factors, one of which being disorders that affect a woman's ability to ovulate. These disorders include:
Polycystic ovarian syndrome (PCOS)
Hypothalamic dysfunction
Premature ovarian insufficiency
Excess prolactin.
A number of disorders that affect ovulation, such as polycystic ovarian syndrome, can lead to infertility. In cases of PCOS, women experience a variety of symptoms due to hormonal changes and imbalances. These imbalances lead to disruption in ovulation, as well as insulin resistance, obesity, abnormal hair growth and acne. PCOS is the leading cause of infertility in women.
Hypothalamic dysfunction is most evident in women who experience menstrual irregularities or amenorrhea (no menses), due to disruption in the production of the hormones responsible for ovulation - follicle-stimulating hormone (FSH) and luteinizing hormone. Causes of hypothalamic dysfunction include excessive physical or emotional stress, extreme body weight or substantial changes in weight (gains or losses).
Premature ovarian insufficiency (premature cessation of egg production) can be caused by autoimmune diseases, genetic abnormalities or environmental toxins. Women affected by this condition are typically under the age of 40, and additionally experience a decrease in their estrogen levels.
In certain situations, such as medication intake or a pituitary gland abnormality, women can produce excessive amounts of prolactin that in turn causes a reduction in estrogen production. Excess prolactin is a less common cause of ovulatory dysfunction.
Ovulation induction
Ovulation can be induced with the use of medication called fertility drugs. These medications are known to regulate, induce or trigger ovulation for a variety of reasons. To treat anovulation - cessation of ovulation - doctors may prescribe certain medications to aid in egg production and release and include:
Clomiphene citrate (Clomid, Serophene): this oral medication increases pituitary secretion of FSH and LH, causing stimulation of ovarian follicles.
Human menopausal gonadotropin or hMG (Repronex, Menopur) and FSH (Gonal-F, Follistim AQ, Bravelle): these injectable medications are known as gonadotropins and stimulate the ovary to produce several eggs for ovulation. The medication human chorionic gonadotropin (Ovidrel, Pregnyl) matures eggs and subsequently triggers them to be released during ovulation.
Metformin (Glucophage): this medication is typically used in women with PCOS to treat insulin resistance that increases the chances of ovulation.
Letrozole (Femara): this medication is an aromatase inhibitor and acts like the drug clomiphene, although it is not used as frequently due to the lack of information on its effect on early pregnancy.
Bromocriptine (Parlodel, Cycloset): this medication is used in cases of high prolactin levels interfering with ovulation.
Culled and edited. Images: Google/MNT/WTE
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