The conception calculator is a simple and quick way to estimate when the sperm fertilized the egg, starting the pregnancy, and is generally calculated from the start date of the last menstrual period.
If you are pregnant, or suspect that you may be, and want to know the period in which conception should have occurred, enter your details into the calculator:
How is the calculation done?
The period of days presented in the calculator’s results is calculated based on the concept that conception tends to occur between 11 and 21 days after the start of menstruation, as these are the days when the woman is most fertile. Understand better when the fertile period occurs.
Like this, it is enough to know the first day of the last menstruation to get the result, adding 11 and 21 days to know the first and last day of the period in which conception should have occurred. For example: if the first day of the last menstruation was on the 4th, this means that +11 and +21 days must be added to this number, obtaining the period of days between 15 and 25.
Are there other ways to calculate?
In addition to the calculation made from the date of the last menstruation, there are two other ways that can be used to try to find out the date of conception. They are:
- From the approximate date of delivery: It is mainly used when the woman cannot remember the exact start date of her last menstrual period, but knows the likely date of delivery. From that date, just remove 40 weeks to find the first day of the last menstruation. Then just add 11 and 21 days to that date to find out the period in which conception should have occurred.
- From the ultrasound: this type of examination is carried out during prenatal consultations and allows the baby’s development to be assessed. In this way, in the first few weeks the doctor is able to estimate a gestational age based on the fetus’s development process, which can help to understand when conception occurred.
Whenever there are doubts regarding any of the pregnancy dates, it is advisable to consult an obstetrician who will be able to resolve the main questions based on the information provided by the pregnant woman. See other ways to calculate the date of conception.
Is it possible to know the exact day of conception?
There are several factors that can affect the moment of conception, which is why, in most cases, it is almost impossible to identify the exact day of conception.
The exact day of conception is more easily identifiable in women who have only had one sexual intercourse during the period 11 to 21 days after their last menstrual period.
Still, fertilization of the egg generally does not occur immediately after ejaculation, as the sperm needs to move to the egg, and therefore it can take up to 5 days to happen. This is the maximum time that sperm can survive inside a woman’s body and under ideal conditions.
Bibliography
- ANDERSON, R. A.; et al. Predicting human conception: the elusive ‘fertility test’. BMJ Sex Reprod Health. 46. 4; 237-238, 2020
- TONSON, B.; et al. The Endometrial Microbiome and Its Impact on Human Conception. Int J Mol Sci. 23. 1; 485, 2022
