Contents
What is the due date, or APD?
As soon as you arrive in the office of your obstetrician-gynecologist, midwife or general practitioner, to announce your pregnancy, the healthcare professional grabs a “pregnancy disc”Sliding window and asks you for the date of your last period. The goal: to estimate the date of the onset of pregnancy, and thus obtain the expected date of delivery, also called DPA.
As the name suggests, the due date is a theoretical date. It makes it possible to assess “roughly”When the pregnancy will come to term, and therefore a priori when the childbirth will take place in relation to the presumed start of the pregnancy.
How to calculate the expected date of delivery, or APD?
Apart from an ultra-regular ovulation, or aided by ovulation inducers (for example in the event of ovarian stimulation or IVF), it is rarely possible to determine with precision the date of ovulation, which corresponds to the start of pregnancy.
Also, during the first medical examination to confirm the pregnancy, the obstetrician-gynecologist or midwife usually brings a “pregnancy disc”Where it indicates the date of the first day of the last period. Because it is this date that will make it possible to estimate ovulation, which occurs on average 14 days later. In France, the APD is calculated by adding 9 months to the date of ovulation.
Take, for example, the case of a woman whose last period is June 1. It is then considered that ovulation took place 14 days later, i.e. June 15. The CCA is then set for March 15.
Dating ultrasound to calculate the due date
Because not all women ovulate exactly on day 14 of their menstrual cycle, which also doesn’t necessarily last 28 days, the very first pregnancy ultrasound, or dating ultrasound, can help pinpoint the expected date of birth. childbirth.
Usually performed between the 11th and 13th week of amenorrhea, the dating ultrasound includes, among others, the measurement of cranio-caudal length (or LCC) of the fetus, which will be compared to a reference curve to estimate the age of the fetus. In this way, the practitioner can estimate the date of the onset of pregnancy (in other words, ovulation), to within a few days. By adding 9 months, we get the expected date of delivery.
Expected delivery date: can we trust it?
The expected date of delivery is above all an approximate date, on the one hand because few babies are born within nine months of pregnancy to the day, and on the other hand because the starting calculations may be inaccurate. .
If it is only calculated in relation to the first day of the last menstruation, the CCA should be considered with caution. This calculation in fact includes a large margin of error, in the sense that it is based on a 28-day menstrual cycle, with ovulation occurring on day 14 of the cycle. And even if the egg was expelled on the date it is believed, it is also possible that it was not fertilized until 24 to 48 hours later, which can further distort the calculation. . The exact start day of your last period can also be inaccurate, if you have irregular bleeding or if the bleeding does not really look like “real” periods.
When refined by dating ultrasound, by measuring the cranio-caudal length of the fetus, or even by other measurements, the presumed date of delivery is a priori more reliable.
But then again, this DPA should not be taken as “cash”Considering that the baby will be born precisely on that day.
Remember that a baby is considered premature if it is born before 8 and a half months of pregnancy, i.e. 37 weeks of amenorrhea, while the term of pregnancy corresponds to 41 weeks of amenorrhea.
Due date: why is it so important?
If the due date isn’t that reliable, then why bother? As it turns out, while it shouldn’t be over-focused on this date, the DPA is essential at the medical and administrative level, where it serves as a calculation benchmark.
The expected date of delivery depends in particular on the personalized pregnancy follow-up, with among other things the different dates of the three ultrasounds. APD is also an indication as to when the pregnancy is considered to have come to term, and therefore when it is good to induce childbirth to avoid complications.
On the administrative side, the presumed date of delivery is the one used by Health Insurance for the calculation of the dates of maternity leave. Because this breaks down into 6 weeks of prenatal leave, before the presumed date of childbirth, to which are added 10 weeks of postnatal leave, after childbirth (in the case of simple pregnancy and if it is ‘a 1st or 2nd child).
The expected due date will also allow dad to know roughly when his paternity leave will be.
Beyond these calculations, the expected date of delivery above all allows future mothers and fathers to organize themselves before the birth of the baby.