Many infertility patients in the clinic often ask the same question, “Doctor, how can I know when to ovulate?” . A normal woman only ovulates once a month, and the egg is very vigorous within 24 hours from the ovary, while the sperm can only survive 24 to 48 hours in the woman’s body. So how to predict ovulation? Below I introduce several common methods for your reference. 1, ovulation test paper monitoring: In the week after the end of menstruation, use ovulation test paper to test once a day. If you find that the ovulation test paper is gradually increasing from strong positive, you should strengthen the frequency of testing, preferably once every 4 hours. If you compare the test strips and find that the ovulation test strips start to weaken and turn weak quickly, it means that ovulation is imminent and you can arrange intercourse. The time frame for ovulation is usually within 24 to 48 hours after the ovulation test paper becomes weak. 2.Menstrual cycle projection: Women’s menstrual cycle starts with the first day of menstruation and ends with the next menstruation. For women with normal menstrual cycles, the interval between the day of ovulation and the start of the next menstrual period is relatively fixed, usually around 14 days. Then, according to this relationship between ovulation and menstruation, ovulation can be projected according to the menstrual cycle. The method of calculation is to count down 14 days or subtract 14 days from the first day of the next menstrual period to the day of ovulation, and the day of ovulation and the 5 days before and 4 days after it are called the ovulation period. For example, if the menstrual cycle is 30 days, and the first day of menstruation is on September 29, then the next menstrual period will be on October 29 (September 29 plus 30 days), and then subtract 14 days from October 29, then October 15 will be the day of ovulation. The day of ovulation and the five days before and four days after it, that is, the ten days from October 10-19, are the ovulation period. In order to use this method to calculate ovulation, it is necessary to know the length of the menstrual cycle, that is, to have a normal or regular menstrual cycle in order to calculate the start date of the next menstrual period and thus to calculate ovulation, so it can only be used for women with normal menstrual cycles. If the menstrual cycle is irregular or abnormal, the date of the next menstrual period cannot be calculated and therefore the day of ovulation and the ovulation period cannot be calculated. For irregular periods, the formula for calculating ovulation is: first day of ovulation = days of the shortest menstrual cycle minus 18 days; last day of ovulation = days of the longest menstrual cycle minus 11 days. For example, if the shortest menstrual period is 28 days and the longest is 37 days, you need to subtract 18 (28-18=10) from the shortest regular period and 11 (37-11=26) from the longest regular period, so the 10th to 26th days after the menstrual flow belong to the ovulation period. 3.Observation of cervical mucus properties: Usually 1-2 days before ovulation, the vagina becomes more and more moist and the discharge increases, and it is unusually thin, very malleable, clear and transparent like an egg, and stretches for a long time, the appearance of such leucorrhea indicates that ovulation is imminent and usually lasts 3-5 days. In other periods, the vaginal discharge is very little and appears to be thick and viscous. 4.Measurement of basal body temperature: The body temperature of a normal woman measured immediately after waking up from a full night’s sleep is called the basal body temperature, which is usually measured early in the morning before waking up. A sign that ovulation has begun is a slightly elevated basal body temperature. You can take your temperature at a fixed time every morning before you wake up and then record the number as a curve. In the period before ovulation day, the basal body temperature is usually below 36.5°C. By the day before ovulation day, the temperature drops a little more, and the lowest temperature is on the day of ovulation. One day later the basal body temperature starts to rise by more than 0.5°C, via about 12 to 16 days until the onset of menstruation. Each woman can calculate her ovulation day from the lowest day according to this regular basal body temperature. According to statistics, ovulation occurs at the lowest temperature in 40% of cases, 1 day after the lowest point in 30% of cases, 1 day before the lowest point in 15% of cases, and in very few cases, 2 days before and after. Ultrasound monitoring of ovulation: Ultrasound monitoring of ovulation is the most accurate method at present. Ultrasound can directly observe the morphological changes of follicles and understand the whole process of follicular development and ovulation, and can also determine whether ovulation is occurring and predict ovulation. The human egg matures once a month from one ovary, “squeezes” out of the ovary and is released to swim towards the fallopian tube, a kinetic process. This process of leaving the ovary takes about 1 to 2 minutes. At this point the follicle ruptures and the egg emerges, causing a slight bleeding. If the bleeding site happens to be against the peritoneum at this time, it can produce an uncomfortable sensation, a vague painful sorrow, called intermenstrual pain. The feeling of intermenstrual pain is not exactly the same for everyone, some do not feel pain and sorrow but only a burst of soreness in one side of the lower back, while some women feel swelling in the lower back, and some women do not even experience any discomfort. Women who experience this sensation can pay attention to how they feel around the estimated time of ovulation based on their past experience. Although ovulatory bleeding and ovulation pains are indeed phenomena that occur during ovulation, this phenomenon does not happen to everyone and does not happen every month. So you definitely won’t be able to use it as a sole method. It will make you waste a lot of time, however, it is perfectly fine to use it as an auxiliary method of judgment. Ovulation pains, in particular, are often more accurate once you feel them. All of these methods above can sense ovulation, but the degree of accuracy can vary greatly. The least accurate of these is calculating the day of ovulation, while the more accurate is ultrasound monitoring, the more convenient is ovulation test strips, the most troublesome method is taking your temperature every day, and the methods that cannot be used as a routine to determine ovulation are ovulation bleeding and ovulation pains.