You’ve just found out you’re pregnant, and perhaps one of the first questions friends and relatives ask—after the usual congratulations—is When will the baby be born? You can estimate the expected due date by considering certain factors, such as the date of your last menstrual period, and allowing a margin of fifteen days before and after within the month, during which the baby is considered full-term.
Pregnancy Calendar: why is it important to know the estimated due date?
For the expectant mother, the estimated due date is helpful for starting to plan and organize the home for the newborn’s arrival and to welcome them in the best possible way. For the gynecologist and midwife, the due date helps schedule check-ups and tests during pregnancy based on gestational age. In addition, the estimated delivery date is used to assess fetal development, which should align with the different stages of gestational growth, and it helps the gynecologist be prepared in case of a possible premature birth.
La gravidanza dura in media 40 settimane, ma il parto può avvenire in anticipo a partire dalla 37° settimana o andare oltre fino alla 42°.
Date of birth: how is the estimated due date calculated?
There are several ways to calculate the alleged date of delivery ; gynecologists and midwives use tables, and you can also find calculators online. To estimate the due date, it helps to know that pregnancy lasts an average of 40 weeks (280 days), about 9 months, and that pregnancy weeks are counted starting from the date of the last menstrual period (the first day of the last cycle). Gestational age is therefore not measured from the moment of conception, which can be uncertain. By convention, the due date is calculated by counting 280 days from the first day of the last menstrual period, allowing for a margin of plus or minus 15 days.
As mentioned, obstetricians and gynecologists use tools such as the obstetric ruler : a tool made up of two overlapping cardboard disks that can rotate clockwise and counterclockwise. It is a true circular calendar with dates and numbers displayed , used to calculate How many weeks pregnant are you? , the alleged date of delivery , and other data concerning child development .
Another calculation that expecting parents can use to determine the expected delivery date is based on a simple mathematical operation known as Naegele's rule : add seven days and subtract three months from the date of the last menstruation.
If you can’t remember the date of your last period, or if your cycle is very irregular, the due date will be assessed during the first ultrasound for greater accuracy.
Pregnancy Calendar: stages of pregnancy from the 1st to the 38th week
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The first quarter starts from the moment of fertilization and continues until the twelfth week of pregnancy ; it is a very delicate phase because it marks an important period for the development of the child's organs , which happens very rapidly. The heartbeat can also be seen on ultrasound.
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The second quarter goes from the 13° to 24° week , and is usually a pleasant time for the pregnant woman; in most cases, the initial nausea disappears, and she begins to feel the first movements of the baby . The mother’s belly grows, and by the end of the second trimester, the baby weighs about 700 grams.
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Nel third quarter of pregnancy (25th-38th week) the baby’s body and organs fully develop, and the time to meet your baby is getting close. Starting from the 8th month, the first contractions may appear ; the baby prepares for birth by positioning itself cephalically, meaning head down. The baby’s weight is about 3 kg, and the pregnancy journey is nearing its end.
How does the calculation of pregnancy weeks work
The pregnancy week count is a very simple calculation that, as mentioned earlier, gynecologists and midwives perform using various methods such as tables or online calculators. Pregnancy week tables are divided into trimesters of gestation, precisely because the stages of fetal development within each trimester differ from one another.
The gestational age of the fetus is expressed by two numbers separated by a “+”. The count takes into account the full weeks and days that have passed since the first day of the last cycle, which is indicated as day 0+0 (0 weeks + 0 days). Then you have 0+1, 0+2, up to the completion of week 0+6. After the first week is completed, the calculation continues with 1+0 (1 week + 0 days), and so on.
This is why knowing gestational age more precisely allows for accurate monitoring of fetal growth, which is assessed by comparing it with the average sizes of children of the same gestational age. This careful analysis allows for the prompt detection of any pathologies.
Pregnancy is a period of great change for a woman: the body changes, emotions can feel more intense, and fears about childbirth are common. Talking, sharing, and—above all—informing yourself is an additional way to face each stage of pregnancy and life as a future mother with serenity; that’s why we suggest you subscribe to our #momlife newsletter to receive personalized content designed specifically for you.
Frequently Asked Questions
Foire aux questions
Why is the expected expiration date important?
Why is the expected expiration date important?
How is the date of birth determined?
How is the date of birth determined?
How are pregnancy weeks counted?
How are pregnancy weeks counted?
How accurate is the calculation of the estimated due date?
How accurate is the calculation of the estimated due date?
How to determine which week of pregnancy you are in?
How to determine which week of pregnancy you are in?
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