Our today topic is date of delivery and the duration.We will share some information about date of delivery.After obtaining a positive result with a pregnancy test, the natural question is the expected date of delivery. Establishing a specific date is, however, more complicated than we think.In general, specialists estimate that a pregnancy lasts 280 days or 40 weeks. However, some studies now indicate that a normal pregnancy would actually be a little longer. For a first pregnancy, about half of the women would give birth after 40 weeks and 5 days, that is to say 285 days. In the case of a second pregnancy, it is 40 weeks and 3 days.
Date Of Delivery
Some women may also experience a longer pregnancy. The same study reveals that a quarter of pregnant women with a first baby give birth after 41 weeks and 2 days of pregnancy. In theory, however, no woman would exceed 300 days, that is, 42 weeks and 6 days. In fact, the doctor will generally offer the pregnant woman to induce labor between 41 and 42 weeks of pregnancy, because the risks of continuing the pregnancy would then be greater than those of causing childbirth.
In general, health professionals talk about pregnancy in weeks, not months, since it is more specific. Pregnancy weeks are also divided into 3 trimesters:
1st trimester : from fertilization to 14 weeks
2nd trimester : from 15 weeks to 28 weeks
3rd trimester : from 29 weeks to birth
How to calculate the expected date of delivery
The majority of doctors and midwives use the Naegele rule to calculate the expected date of delivery. Basically, this rule was to add 7 days to the first day of the last menstrual period and then to 9 months.
This was problematic, however, since not all months had the same number of days, which theoretically varied the duration of the pregnancy. For example, for a woman whose last menstruation took place in May, the pregnancy lasted 283 days while she had only 280 days for a woman whose last menstrual period began in June. Now, professionals will say instead that the expected date of delivery will be 40 weeks after the first day of the last menstrual period.
The doctor or midwife calculates the first 2 weeks after the last menstrual period in the number of weeks of pregnancy, even if the mother was not yet pregnant. Thus, when we talk about “20 weeks of pregnancy”, we refer to the 20 complete weeks that have elapsed since the first day of the last menstrual period.
Small wheels manufactured by pharmaceutical companies to determine the expected date of delivery are not recommended because their quality is very poorly controlled. From one roulette to the other, there are sometimes up to 5 days difference in the calculation of the date. It is best to have 40 weeks on the calendar or use a childbirth date calculator on the web.
Is the expected date of delivery reliable?
Date Of Delivery
Although Naegele’s rule has been used for more than 200 years, it is criticized by many health professionals.
Naegele’s rule is based on the idea that a menstrual cycle lasts 28 days. Yet, many women have irregular cycles. In fact, 30% of women say they have a cycle of at least 30 days.
The rule Naegele assumed that ovulation occurs exactly on 14 th day of a 28 day cycle, which is not the case for most women. In fact, in the general population, ovulation tends to take place after the middle of the menstrual cycle. In women who have a cycle of 28 days, only 10% ovulate 14 th day and only 30% of these women are fertile between 10 th and 17 th day of the cycle.
Many women do not remember the date of their last menstrual period. According to a 1985 study, 79% of women are certain of the date of their last menstrual period, that is, they can determine the week in which they occurred.
The rule does not take into account that some embryos may take longer to implant in the lining of the uterus, which lengthens the pregnancy.
If the last bleeding is light, it may be not the last menstruation, but rather an intermenstrual bleeding or bleeding caused by implantation of the embryo into the uterus.
In fact, using the date of fertilization would give more accurate results than the date of the last menstrual period. However, the majority of women are not aware of their ovulation. Indeed, temperature-sensing techniques or kits measuring reproductive hormone levels are needed to detect ovulation.
For this reason, many professionals conclude that the expected date of exact delivery does not exist. Moreover, barely 4% of women give birth on their expected date of birth. A mother should be talking about a planned delivery week or even a birth month.
A misinterpretation of the Naegele rule?
Naegele’s rule was actually enunciated by a Dutch doctor called Boerhaave in 1744. In its original form, the rule only mentions adding 7 days to the last menstruation, without specifying whether to start at the first or the last last day. The rule was therefore interpreted differently from one doctor to another until the early 20 th century. It was then that American medical books chose to add 7 days to the first day of the last menstruation.
The use of ultrasound
An ultrasound done in early pregnancy would be more accurate than the date of the last menstrual period to determine the expected date of delivery. This is especially true if the ultrasound is performed between 8 and 16 weeks of pregnancy. The technician then measures the height of the baby, from the top of his head to the buttocks. As babies develop very similarly in early pregnancy, it is then possible to make a connection between this measure and the duration of the pregnancy. The accuracy of this measurement may however vary from ultrasound to ultrasound.
Date Of Delivery
If the date calculated using Naegele’s rule differs from that obtained by ultrasound by more than 7 days, the physician may choose to change the expected date of delivery to reflect the outcome of the first trimester ultrasound. If the ultrasound is performed between 12 and 20 weeks, the difference should be more than 10 days for the doctor to consider changing the date.