"My labor was induced a week after the estimated due date," complained a young acquaintance to me.
Errors in calculating the estimated due date are very common. In obstetrics, it is customary to calculate the due date using the formula of the German obstetrician Franz Nägele: subtract 3 months from the first day of the last menstruation, add 7 days, and add a year.
This same method of calculation is used by most popular online pregnancy calculators.
If you have a so-called classic 28-day cycle and ovulation occurred on the 14th day of the cycle, then you belong to the 4% of women whose due date coincides with the estimated due date.
In all other cases, the Nägele formula gives an erroneous result because it does not take into account the length of menstrual cycles and the date of conception.
The lady mentioned earlier had long cycles of 35-37 days, which were not taken into account when calculating the estimated due date and ultimately led to induced labor. She questioned the accuracy of the estimated due date calculation because her body, by all indications, was not ready for childbirth.
I suggest two formulas that will help you more accurately calculate the due date and take into account such parameters as cycle length and date of conception.
If you have non-standard cycles (more or less than 28 days), the Parikh formula for calculating the estimated due date will suit you.
Parikh's formula: the first day of the last menstruation + (add) 9 months - (subtract) 21 days + (add) the duration of the previous cycle.
If you know the date of conception exactly, you can add 266 days to this date and get the estimated due date.
How can you know exactly when the child was conceived, you may ask?
There is only one day in your cycle when the egg can be fertilized - that's the day of ovulation. Read more about tracking fertility biomarkers and determining ovulation here.
If you are only planning a pregnancy, I highly recommend tracking fertility biomarkers and recording ovulation. This will not only help you plan your pregnancy but also more accurately calculate the due date. Find out more articles on pregnancy planning using the hashtag #healthypregnancy
If you are already pregnant, think about what method of contraception you will use after the birth of the child and study the possibilities of natural fertility management in advance to feel calm and confident after childbirth.
Share in the comments when your children were born, earlier or later than the estimated due date?
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