A trimester is three months, which is equivalent to twelve weeks. In the gynecological calendar, the trimester is 93.3 days, given that the entire pregnancy lasts 280 days. It is considered from the first day of missed menstruation or from the last day of the menstrual cycle.
Duration of pregnancy by calendars
If there are 365 days in a year, then pregnancy is 9 months. However, in February there are 28-29 days, every second month has 31 days, and here it is rather difficult to determine the calculations. To calculate the date of birth, arithmetic alone is not enough. The obstetric calendar consists of months, each of which has 28 standard days. In general, this is ten months, and trimesters are not 90 days, but 93. Even if you average the first three months from January to March, you get 92 days, only February compensates for the days.
How to determine the date of birth and contractions?
Due to the difference in the number of weeks, a pregnant woman may incorrectly calculate the expected date of delivery. For this you need to resort totwo ways:
- If the date of conception is known, add 264 days to it.
- If the date of conception is unknown, then from the first day of menstruation, count back 3 months (subtract) and add seven days. For the convenience of calculations, you can first add a week, and then subtract a trimester.
For example, the last day of my period was December 1st. So from September 1 (the trimester was taken away), we count + 7 days, and it turns out September 7-8 - this is the estimated date of birth.
The surest way to find out the due date
And today, ultrasound is considered the surest way to set the date of birth. According to its results, it is clearly visible how the baby develops and grows all 9 months. If the trimester is three months, then from 6-7 weeks after conception, the diagnostician can tell exactly when replenishment should be expected. It is worth noting that children are not always born on time, and at 33-35 weeks you need to undergo an appropriate ultrasound. It is required for:
- determining whether the child is developing correctly;
- should we expect an advantage;
- whether a caesarean section will be needed;
- how much does the baby weigh;
- how the fetus develops;
- where the baby is located in relation to the uterus.
Therefore, it is important to understand that trimesters are how many weeks are included in 1/3 of the duration of pregnancy. You should not refer to the standard definitions that three months from the beginning of the year is the correct count, and everything else is only a part of the previous and subsequent periods. Trimesters at school also have three quartersfor 3 months, and the summer quarter is a vacation.
Egg development by trimesters
If you move away from arithmetic, you can consider systematically how the cell develops and conception occurs. Fertilization takes from 24 to 96 hours, so if you have an unwanted pregnancy, you should use urgent methods of contraception in the first 24 hours. The male sperm cell lives for 5 days, and from the first minutes it begins to move towards the egg. The fusion of the male and female nuclei into a cell signifies fertilization. Next, cell division occurs, after which the embryo moves through the tubes into the endometrium of the uterus.
The egg is attached to the wall and in a week you can already start the countdown. Pregnancy has begun, which means that the first trimester has come. Further, the fetus develops monthly and increases in size.
First trimester - how life is born
The first stage is the most difficult and exciting. In these three months, you should take care of yourself and the fetus. Several interconnected cells develop from day to day. Chorionic gonadotropin (hCG) is produced. It sends a signal to the corpus luteum about the need to produce progesterone. The hormone enters the urine, the reaction is reflected in pregnancy tests and when taking tests. The first trimester is how many months? Everyone has the same - 3 calendar months and 3, 4 obstetric. A tube of the nervous system appears in a child, two thickenings, a liver and a brain are formed.
- You can also see the outline of the baby.
- There are "cells" for the eyes and nose.
- Fingersalready formed with the nail plate.
By the end of the third month, the heart is formed from one chamber, and by the beginning of the second trimester it is possible to establish a heartbeat during ultrasound.
Second trimester - organs develop
When the organs of the digestive system are formed, the fetus actively develops and gains weight. Not so fast, but rapidly forming the brain. The heart already consists of 4 chambers, and the respiratory system is completely "ready" to work. By the middle of the second trimester, by the 5th month, the fetus begins to move its legs and arms. The blood vessels are not yet perfect, but cartilage is already gradually being replaced by bone.
By the end of the second trimester, the baby reaches a size of 18-24 cm (depending on genetics). During this period, the mother should focus on taking vitamin C, glucose and iodine. Avoid infections and viral diseases. At the end of the sixth month, the baby will be able to distinguish sharp sounds, startle, react to light, smell. He can already distinguish his mother's voice from extraneous sounds. For a child, the 2nd trimester of pregnancy is very important, because in these weeks he is practically preparing for the birth. At birth at 7 months, the baby is considered a viable and full-fledged child.
Third trimester - the laying of the senses and weight gain
No wonder doctors say that the main weight gain occurs in the 9th month. Moms should pay close attention to nutrition:
- By the third trimester, the baby already weighs 1500 grams, and if the mother is activeeat, then for the last 3 weeks of pregnancy, the child will add 35 grams per day. And this significantly increases the chance for a cesarean.
- Babies can open their eyes and see by 7 months.
- The respiratory system is improving.
- Swallowing reflexes are formed. It is not uncommon for babies to swallow amniotic fluid.
- Fetal hiccups may occur.
By the 8th month of life inside the mother's womb, the height of the child is 40-45 cm, and the weight reaches 2200 grams approximately. The ninth month is "useless" for the baby, as he "lives out" his days inside, preparing for the birth. His skin becomes smooth, a protective fluff appears, the surfactant in the lungs actively lubricates the alveoli so that they do not stick together. At the first breath, they will open, and the baby will experience a slight tingling, which will make him cry.
The tenth obstetric month - the sacrament of birth
When the 40th week comes, the baby is actively moving out through the birth canal. The placenta is the only living organism in the world that lives for 9 months and then dies. This is a "house" for the baby, his habitat, and the older she is, the sooner the baby gets to know his parents. What is the trimester for an obstetrician who considers the 10th month the stage of the birth of a child?
That's 18 extra days, which is the difference between 9 and 10 months. If the pregnancy is delayed, then the baby will appear at 41-42 weeks. And this is a full-fledged 10th obstetric month, which,as a rule, in medical practice it is considered the norm. In just a few hours, the baby manages to overcome a serious and difficult path to meet his mother:
- lubrication is produced to coat the alveoli;
- baby rolls over;
- the head drops sharply into the bosom of the pelvis;
- first fight begins;
- opening the birth canal;
- pelvic bones expand;
- opening the cervix is often painful - up to 4 cm you have to wait almost 8-10 hours;
- baby moves down with the help of mom;
- the head enters the birth canal, expanding the walls of the cervix.
The head is shown, the body is expelled - the baby is born. All these trimesters he lived inside and in an instant found himself on the other side of his "house". A miracle happens - the first meeting with mom.
