1, disadvantages of early expiration date
The medical definition of a full-term fetus refers to an infant whose gestational age is between 37 weeks and 42 weeks. About 80%-90% of pregnant women give birth during this period. Premature delivery is less than 37 weeks, accounting for about 5%- 10%. The younger the gestational age, the weaker the life ability of premature infants. Therefore, if expectant mothers have labor symptoms before the 37th week of pregnancy, they should immediately go to the hospital to protect the fetus and prolong the time of the fetus in the uterus as much as possible.
2. Disadvantages of delaying the due date
If the fetus is in the mother's womb for too long and the gestational age is more than 42 weeks, it is called an expired fetus. There is a saying that the longer the fetus is in the belly, the better. There is no scientific basis for this. For every mother, the placental function maintains the supply of oxygen and nutrients to the fetus for about 38 weeks, and then gradually declines. In some cases, the placenta degenerates in advance, and the longer the expiration time, the worse it is for the fetus. Many women have an emergency cesarean section before 42 weeks of pregnancy because of lack of amniotic fluid. If such a fetus is born a few days later, it may die in the uterus.
3. What is the normal range?
In the final analysis, the expected date of delivery is only an expected delivery time, and the exact delivery time is also related to a series of self-factors of pregnant women. The difference between each expectant mother's normal pregnancy can reach 5 weeks. For example, older pregnant women have a longer pregnancy, and women who are heavier at birth tend to have a longer pregnancy, while women who have a longer pregnancy in the previous pregnancy will still have a longer pregnancy in the second pregnancy.
The reasons why the baby in the pregnant woman's belly is born at full term, to the expected date of delivery, and later than the expected date of delivery are mainly as follows:
1, the expected date of delivery is calculated according to the last menstrual wake-up. If the pregnant mother's menstrual cycle is short, the last menstruation is early or late, and the regular menstruation is irregular. The expected date of delivery calculated according to the last menstruation will also have different degrees of error;
2. The mother's psychological state, working state, living condition and nutritional status during pregnancy will all lead to the change of the baby's birth time. If there are pregnant mothers with poor nutritional status, excessive mental stress and overwork, the baby may be premature;
3. The pregnant mother's personal physique and the baby's development in the body are also important factors to determine whether the baby's birth date is earlier or later than the expected date of birth.
Therefore, if the pregnant mother gives birth earlier or later than the expected date of delivery, don't worry too much. As long as the difference between the baby's birth date and the expected date of birth is no more than two weeks, it is usually normal and there will be no big problem.
What I hear most about having children is that melons will fall off when they are ripe. So should having children. But why are some babies born shortly after full term, and some babies born after the expected date of delivery? What is the reason?
The mechanism of childbirth is imaginary, including inflammatory mechanism, mechanical mechanism and even endocrine hormone mechanism. Recent research shows that the start-up of babies is actually related to babies. When the baby matures, it will secrete some mysterious substance, which will lead to cervical softening, that is, cervical maturity (the birth door becomes thinner and softer), and the oxytocin receptor of uterine smooth muscle will increase, which will lead to the increase of uterine sensitivity, and then start contractions and induce delivery.
In the popular version, the fetus is like a fruit. When the fruit is ripe, it will secrete a hormone, which will make the branches at the pedicle of the fruit fall off and the fruit fall off. The same is true for babies. When the baby matures, it will also release a substance that can make the cervix mature, increase the sensitivity of the uterus, and lead to the beginning of labor and the birth of the fetus.
To sum up, the time of fetal delivery is related to the maturity of the baby. When the fetus matures, it will release a hormone that induces childbirth.
I am a second-born mother. My two babies were born at 37 weeks. Only 5% pregnant mothers can give birth in the expected date of delivery, and most of them give birth two weeks before and after the expected date of delivery.
Why are some fetuses full-term, some due and some delayed? The birth of a baby is a phenomenon of "ripe melons falling behind". It is normal to give birth at 37 ~ 42 weeks of pregnancy, and most pregnant mothers may give birth after 42 weeks. This is called overdue pregnancy, which has certain risks.
The menstrual cycle of pregnant women
The length of pregnant mother's menstrual cycle directly affects the implantation time and later development of fertilized eggs. Usually women's menstrual cycle is once every 28 days, mine is once every 25 days. So both babies were born at 37 weeks, which is relatively early. If the pregnant mother has a long menstrual cycle, the delivery event may also be delayed.
Activities during pregnancy
Pregnant mothers who are active during pregnancy will give birth faster, and moderate activities during pregnancy can also stimulate the secretion of body hormones. Under normal circumstances, pregnant mothers who exercise a lot will give birth faster, earlier or faster. Some pregnant mothers like to stay at home, but this is not desirable. Fetuses also need to breathe fresh air.
Fetal development
The nutrition during pregnancy and the constitution of the pregnant mother determine the development of the fetus. If the mother is well nourished during pregnancy, the fetus will also develop healthily. However, if the nutrition is deficient or the pregnant mother is emotionally unstable, it will easily lead to premature delivery of the fetus. In the third trimester, especially zinc supplementation can prolong the pregnancy cycle.
In short, most pregnant mothers will give birth after full term, and the baby will be born healthily if the prenatal examination is done on time during pregnancy and the abnormal phenomena are eliminated in time.
When is the expected delivery date?
The expected date of delivery is the expected date of delivery of pregnant women based on the average duration of human pregnancy. The whole process of pregnancy starts from the first day of the last menstruation, with an average of about 40 weeks. Clinically, for the convenience of calculation, it is usually to add 9 to the month of the last menstruation (if the total exceeds 12, it will be reduced by 3) and then add 7 to the date to calculate the expected date of delivery. For pregnant women who can't remember the last menstrual period at the end of Qing Dynasty and are pregnant while breastfeeding, early pregnancy reaction time, fetal movement start time, fundus height and B-ultrasound examination are often used to help calculate the expected date of delivery.
Medical premature babies refer to those babies who report to the world within 28 weeks to 37 weeks. Full-term babies are from 37 weeks to 42 weeks. As mentioned above, the expected date of delivery is calculated on the basis of 40 weeks of pregnancy. Therefore, this part of the baby born earlier than the expected date of delivery (40 weeks) but more than 37 weeks is full-term, not premature.
Why are there mistakes?
1. Generally, pregnant women suffer from uterine malformations, such as congenital hypoplasia of double horn uterus, single horn uterus, double uterus, uterine mediastinum, etc., which is easy to make the fetus premature, because the uterus is the place where the fetus grows. If the muscles of the uterus can't be stretched well, it is easy to have premature delivery. Cervical relaxation and amniotic sac bulging to the cervical canal can all lead to intrauterine infections such as premature rupture of membranes, chorioamnionitis and premature rupture of membranes, which can all lead to premature delivery. Psychological stress and work stress, long working hours, overwork, poor nutritional status, frequent mood swings and excessive mental stress; Or some mothers are underweight in order to lose weight, which will lead to premature birth.
2. Generally, it is normal to exceed the expected date of delivery by about two weeks. When the pregnancy is greater than or equal to 42 weeks, it is an overdue pregnancy. There are many possible factors leading to delivery, including progesterone blockade, oxytocin stimulation and fetal adrenocortical hormone secretion, and any factor that causes these hormone disorders may lead to prolonged pregnancy. Therefore, overdue pregnancy may be related to the following factors: (1) the proportion of estrogen and progesterone is out of balance; Fetal malformations, such as anencephaly, are related to insufficient secretion of fetal adrenocortical hormone; Genetic factors, etc.
When a female friend is promoted to a pregnant woman, she can always hear many "proverbs" during pregnancy, such as "boys will be born earlier than the expected date of delivery, and girls will be born later than the expected date of delivery". When is the expected delivery date? Is it reasonable to say that boys are born early? Let's learn about "having children early" together.
The expected date of delivery is not "accurate" originally.
The expected date of delivery is the expected date of delivery of pregnant women based on the average duration of human pregnancy. The whole process of pregnancy starts from the first day of the last menstruation, with an average of about 40 weeks. Clinically, for the convenience of calculation, it is usually to add 9 to the month of the last menstruation (if the total exceeds 12, it will be reduced by 3) and then add 7 to the date to calculate the expected date of delivery.
For pregnant women who can't remember the last menstrual period at the end of the Qing Dynasty and are pregnant while breastfeeding, early pregnancy reaction time, fetal movement start time, fundus height and B-ultrasound examination are often used to help calculate the expected date of delivery.
Just as the average height cannot be used to predict the actual height, the expected date of delivery cannot be regarded as the actual delivery period. Moreover, the commonly used clinical methods for estimating the expected date of delivery do not take into account the differences in the number of days in different months, and there is a certain error in itself. In addition, pregnant women do not remember the date of their last menstruation or the menstrual cycle is inaccurate, which may make the estimated expected date of delivery inaccurate. In addition, there are some individual differences in intrauterine development of different fetuses, and there may be a time difference of 1-2 weeks between the actual delivery date and the expected delivery date.
In addition, some pregnant women's pregnancy-related diseases or fetal related factors such as multiple births may also widen the time difference between the actual delivery date and the expected delivery date.
Born before the expected date of delivery, not necessarily premature.
Many pregnant women and their families believe that as long as they give birth earlier than the expected date of delivery, they are premature. In fact, everyone misunderstood the medical term "premature delivery".
Medical premature babies refer to those babies who report to the world within 28 weeks to 37 weeks. Full-term babies are from 37 weeks to 42 weeks. As mentioned above, the expected date of delivery is calculated on the basis of 40 weeks of pregnancy. Therefore, this part of the baby born earlier than the expected date of delivery (40 weeks) but more than 37 weeks is full-term, not premature.
It's really "having a baby early"
Although there are not many clinical research data in China, there are many large sample studies in Europe and America to support the conclusion that the shorter the pregnancy time of the mother, the higher the proportion of boys born, whether premature (babies born at 28 weeks but less than 37 weeks) or full-term (babies born at 37 weeks to 42 weeks).
A Norwegian study analyzed the birth data of about 1967 to 1988, and found that the ratio of male and female babies born earlier than the expected date of delivery (40 weeks) was1.17; Babies born after the expected date of delivery are equal to men and women.
However, a study of a larger population in France found that with the increase of pregnant women's gestational age, the birth rate of male fetuses, whether premature or full-term, is declining. Moreover, this change trend has certain racial specificity, which is very obvious in the white group, but this law has not been found in the black group. However, the sample size of black people collected in this study is very small, which may also lead to statistical differences.
Only some studies on premature infants in China found that the proportion of male infants in premature infants was significantly higher than that of female infants, and there was no reliable data analysis for full-term infants. If we really want to find out whether our babies in China have such a trend, we have to wait for the results of a large sample population study in China.
Why do male babies like to report in advance?
Some people think that the different levels of estrogen and androgen in men and women may make boys develop faster than girls in their mother's womb. We should know that the birth weight of a baby is one of the important standards to measure its intrauterine development level. Among full-term infants, the birth weight of male infants is often heavier than that of female infants. If we compare the pregnancy duration of pregnant women with the same birth weight, we will find that the pregnancy duration of boys' mothers is usually shorter than that of girls' mothers with the same birth weight.
In fact, different sexes have different levels of sex hormones, which actually affects our lives. Just as there are differences between men and women in many physiological indexes such as height and weight, the influence of fetal gender on the length of pregnancy is only one of them.
It is not reliable to judge gender by the length of pregnancy.
It can be seen from the statistical data that "having children early" is reasonable in statistical probability. However, this rule is only for the crowd. For a certain pregnancy process, the real check-in time of a male baby may be later than the expected date of delivery, while the real check-in time of a female baby may be earlier than the expected date of delivery.
Therefore, expectant mothers can't infer the baby's gender according to the comparison between the baby's real "start-up" time and the expected date of delivery. The sex of the baby has been decided at the moment when the sperm and the egg combine, and will not change because of the length of pregnancy. Mothers in China, after the baby is born, the midwife will hold him (her) in front of you for the first time, and then the answer will be revealed naturally!
Pregnancy, pregnancy and childbirth are natural processes of life. For the vast majority of healthy expectant mothers, as long as regular check-ups are guaranteed, there is no need to be particularly anxious about whether their baby will be born before or after the expected date of delivery.
Why are some fetuses full-term, some due and some delayed? The so-called expected date of delivery is calculated from the first day of the last menstruation in medicine. Twenty-eight days is 1 month, 1 month is1pregnancy. However, due to the different development of each fetus, the delivery time of the baby is also different. Only about 5% of pregnant women will give birth at the expected date of delivery, and the remaining 95% will give birth earlier or later, as long as they are pregnant for 38-42 weeks.
However, why is it delayed? There are several specific reasons.
1. The reason of fertilized egg implantation.
Generally, if the menstrual cycle is long, the ovulation period is late, or the same time is late, the fertilization time of energetic eggs will be later, and the implantation of fertilized eggs will be later, which will lead to the difference between the actual pregnancy week of the baby and the pregnancy week of the doctor, but this difference is generally within 2 weeks, which will lead to different delivery times of the fetus, some of which will be advanced and some will be delayed; Generally speaking, pregnant women with short menstrual cycle, early ovulation and early implantation of fertilized eggs are advanced, while pregnant women with long menstrual cycle, late ovulation and late implantation of fertilized eggs are postponed.
2. Fetal development.
From the second trimester, the development of the fetus began to change. Due to genetic factors, pregnant women's nutritional intake, fetal nutritional intake and other reasons, some fetuses develop faster and some fetuses develop later, which also leads to different delivery times. Generally, the fast-growing fetus will be a few days earlier, and the slow-growing fetus will be a few days later.
3. The physical condition of pregnant women.
The delivery time of the fetus is also related to the situation of the pregnant woman. Some pregnant women have various diseases during pregnancy, and hyperglycemia and hypertension during pregnancy will lead to premature delivery of the fetus; Pregnant women work too hard, or bump into their stomachs, get scared, think too much and so on. Will lead to premature delivery of the fetus. Martin's friend worked hard in the field for more than seven months, which led to premature birth of the fetus.
4. Fetal multiple births or malformations
Some pregnant women with multiple births usually give birth early; There are also some intrauterine abnormalities, such as intrauterine hypoxia, intrauterine distress and abnormal fetal position. Early caesarean section and early delivery are needed.
Attention, in fact, as long as the fetus develops normally in the uterus and the mother is healthy, it is normal to give birth at 38-42 weeks of pregnancy, so don't worry too much ~
As the saying goes, almost 90% of babies will be born at full term, that is, after 37 weeks of pregnancy. Full-term pregnancy is defined as 37 weeks, near-term pregnancy as 34 weeks, premature delivery as 34 weeks ago, full pregnancy as 40 weeks, and overdue pregnancy as 4 1 week +6.
The expected date of delivery itself is calculated according to the first day of the last menstruation of pregnant mothers, which is the day predicted by doctors. It does not include factors such as inaccurate menstrual cycle, delayed ovulation and late implantation. Therefore, only about 5% babies will give birth at the expected date of delivery, and about 85% babies will be born at 38-42 weeks of pregnancy.
When the baby begins to give birth is independent of human will. Generally speaking, when the baby begins to give birth, it means that the baby is mature. But in fact, according to the delivery characteristics of other creatures, the fetus has to stay in the mother's stomach for 20 months to be mature. Other animals, such as cows, tigers, lions, etc., will stand and walk at birth, while human babies will learn to walk about 1 year after birth.
Of course, this is related to the weakness of human beings in primitive society. In order to avoid the attack of wild animals, giving birth to the fetus in advance is beneficial to the safety of mother and child. Otherwise, dragging a heavy body to migrate is not conducive to reproduction. This gene is inherited today, so babies have to be raised for a year before they can walk.
Conversely, it is understandable that the fetus is born ahead of schedule, due date, or delayed. For example, the fetus enters the basin early, and the baby is born early because the fetal head drops to stimulate cervical dilatation; Or the fertilized egg is implanted late, the growth and development of the fetus lags behind the gestational age, and the delivery of the baby will be delayed.
The birth of a baby is the result of the joint efforts of mother and baby. Natural delivery is a natural process of "ripening the melon", and delivery can only begin if certain conditions are met.
1, the baby needs to be put into the basin. First of all, the baby should be in the head position, the fetal head and pelvis conditions should be symmetrical, the pelvis should be divided into large and small pelvis, and the opening should be relatively large. The baby's head enters the pelvis through the pelvic entrance, so that the baby can give birth smoothly. Of course, sometimes the baby's breech position can also give birth naturally, but it is more prone to dystocia.
2, meet the conditions of bone birth canal. The distance between the two ischial spines in the middle of the normal pelvis is100 mm. If the fetal head is too big, the baby will not be born. The baby's skull can overlap and contract, but if it exceeds 100mm, natural delivery will be very difficult.
3, the mother's cervix is relatively mature, that is, the soft birth canal should meet the delivery conditions. The soft birth canal mainly includes two parts, one is the disappearance of the cervical canal, and the other is the gradual expansion of the cervical orifice to 10cm, which is beneficial to the smooth delivery of the fetus.
4. The fetus and the mother should release oxytocin at the same time. After the fetus enters the basin, the baby's brain will release oxytocin, and the information of customs clearance will be passed on to the mother. The mother's pituitary gland will also release oxytocin, which will cause uterine contraction, abdominal wall muscle contraction and levator ani contraction, which will make the baby and mother secrete oxytocin and increase uterine pressure. At the same time, the birth canal is very tortuous, and the baby needs to turn over with rotation to give birth smoothly.
If one of the above links can lead to premature or delayed birth of the baby. For example, the mother's uterine contraction is weak (usually a mother with zinc deficiency), and the delivery date is likely to be pushed back. For another example, if the baby enters the basin early, the fetal head drops rapidly, and the fetal head constantly stimulates cervical dilatation, then the baby's birth date will definitely be advanced.
Wish pregnant mother: safe delivery!
This problem should be discussed from several aspects:
First of all, the expected date of delivery refers to the first day of the last menstruation of a normal pregnant woman to the day when she is 280 days pregnant.
For pregnant women with irregular menstruation, abnormal ovulation time or forgetting the last menstruation, it is mainly calculated by factors such as gestational age, early pregnancy reaction time, and ultrasound-induced fetal movement time.
Because each woman's menstrual cycle length and ovulation time are not completely consistent, the calculation based on ultrasound and other factors may also have errors with the actual situation, so there may be a certain gap between the expected date of delivery and the actual size of the fetus, which may lead to the delivery of the fetus being advanced or delayed, or at the expected date of delivery.
Secondly, the expected date of delivery itself is only a time mark, which means that most women will give birth around the expected date of delivery. According to incomplete statistics, only about 5% of the fetuses actually give birth at the expected date of delivery, and most of them give birth within two weeks before and after the first trimester.
Of course, premature delivery and overdue delivery are pathological obstetric conditions earlier than 37 weeks and later than 42 weeks respectively.
Finally, in fact, up to now, the internal mechanism of why most normal pregnant women naturally contract and start delivery around the expected date of delivery is far from being clarified; As for why some fetuses give birth earlier, later or at the expected date of birth, the mechanism is complicated and needs further study in the medical field.
Accurate gestational age and expected date of delivery are of course important, but a difference of 2 or 3 days will not affect the pregnancy test and pregnancy outcome, and only about 5% of pregnant mothers actually give birth in the expected date of delivery, so don't worry about the exact date. A difference of 2 or 3 days is nothing.
Some babies are born at full term, some need to be born before the expected date of delivery, and some are born after the expected date of delivery for many reasons. In fact, the expected date of delivery is only an estimated date, which is calculated according to the average pregnancy duration of mothers. Generally speaking, it takes about 40 weeks from the last menstruation. Clinically, for the convenience of calculation, it is usually to add 9 to the month of the last menstruation (if the total exceeds 12, it will be reduced by 3) and then add 7 to the date to calculate the expected date of delivery.
So the expected date of delivery is only an estimated date, and it is only a suggested date for my mother. It's normal to go out early and come back late.
Why are some babies born after the due date? Generally speaking, it is normal to exceed the expected date of delivery by about two weeks, but when the pregnancy is greater than or equal to 42 weeks, it is overdue, so it is necessary to go to the hospital for examination in time and induce labor in various ways.
In fact, there are many reasons for overdue pregnancy, such as hormonal imbalance, baby deformity, heredity and other factors.
For every mother, I always look forward to the expected date of delivery, and I always hope that my baby can meet me on time. This requires the mother to have a good mood during the whole pregnancy, and to have a checkup on time to ensure the health of herself and her baby. This is the best preparation.