Nature has provided for only one option for an uncomplicated pregnancy - bearing one fetus. Therefore, the situation when two children develop in the mother's tummy is always considered difficult. And even if a woman is feeling well, doctors will treat her more attentively, more sensitively, like a patient with a complicated pregnancy. Unfortunately, expectant mothers of two children at once do not have a lot of information about the development of fetuses - all medical sites, manuals and articles tell mainly about the development of one fetus.
But pregnancy with twins is different. This article will provide a weekly overview of multiple pregnancies.
First month - conception and implantation
The first week of pregnancy in obstetrics is the week when a woman is still having her period and conception has not yet occurred. A woman can conceive a child only during the fertile period, when the egg leaves the follicle, ovulation occurs. On this day, which usually falls in the middle of the menstrual cycle, and also within 24-36 hours after ovulation, conception can theoretically occur. Thus, on the day of conception, a woman is already 2 weeks pregnant.
Conception of twins has its own characteristics. Usually, nature provides for the maturation of only one egg, the growth of the rest in the ovaries is suppressed at the hormonal level. But sometimes a well-oiled natural mechanism fails, and on the day of ovulation, two eggs are released into the fallopian tube at once. In this case, both can be fertilized, and then dizygotic twins or twins will be born. They will develop in the same mother's womb, but each will have its own genetic set, and such children will not be alike. Each baby will have its own placenta, they may well be of different sexes.
It is possible that one of these dizygotic twins will be blond, and the other a brunette. At birth, they will differ significantly in height and weight, they will have different characters, temperaments, talents and inclinations, tastes and preferences.
Monozygotic twins are born as a result of the fertilization of one egg. After the paternal and maternal germ cells exchange genetic information, one zygote is formed - an independent cell with its own set of DNA. The reasons why the zygote suddenly doubles is not known for certain to science, but its splitting into two separate zygotes occurs within the first two days after fertilization.
If such a separation occurs within the first three days, then the twins will each have their own membranes and placenta, but if the separation occurs later, then twins are formed, which will feed from the same placenta. If the separation occurs late, two weeks after fertilization, then there is a high probability of the formation of conjoined Siamese twins.
Gemini, since they are descended from originally a single zygote, have an identical genetic makeup, being an exact copy of each other. Such children are of the same sex, and if they inherit a genetic disease, then it is inherent in both.
At 3-4 weeks of gestation, while cleavage is taking place or two separate fetal eggs descend into the uterus, implantation occurs. The embryos adhere to the endometrium, are introduced into it by the chorionic villi and begin to receive nutrition from the mother's blood. Fetal structures begin to form.
In this case, twins or identical twins acquire another classification.
- Bichorial diamniotic - children who each have their own membranes and their own chorion, which will then become two separate placentas. Such a pregnancy is considered the safest and most optimal, most often this happens when twins are conceived from two different eggs and only in 30% of cases - when multizygous twins are conceived.
- Monochorionic diamniotic - children who have a single placenta for two, but each has its own fetal bladder. This happens in 60% of cases when conceiving identical twins and almost never when conceiving twins.
- Monochorionic monoamniotic - children who have one placenta, different umbilical cords that are attached to it. At the same time, babies are inside one for two ovum.
By the end of the fourth week of pregnancy, these features are usually already acquired. Only mom doesn't know anything about it yet. The end of 4 weeks is the waiting time for the next menstruation, which never comes. And mom's head is still busy with the diagnosis and confirmation of pregnancy. The main surprise - twins, is not yet obvious.
Subtleties of diagnosis
In the early stages, the diagnosis of multiple pregnancies is somewhat difficult. The only thing that can indirectly indicate that there is not one baby, but two in the mother's womb, is hCG indicators. This hormone is produced by the chorionic villi after implantation, and its concentration increases every two days. Therefore, a blood test for human chorionic gonadotropin, performed on the day of the delay, a couple of days before or after the delay, can theoretically show double values relative to the norm, but only if the twins are dichorionic.
In this case, the double efforts of two chorions will lead to double the values of the hormone, which is necessary to maintain pregnancy.
Twins who have one chorion will not be "noticeable" on hCG tests. And it will be possible to determine them only after 8-9 weeks of pregnancy on an ultrasound scan - an ultrasound examination will show two embryos.
On a homemade strip test, a woman at 4 weeks of pregnancy, alas, can only determine the very fact of having an "interesting position", but not the number of fetuses. Signs of early pregnancy will also not differ from signs of singleton pregnancies.
Development of fruits at different times
So, conception and fertilization took place. The woman took the test in the first week after the delay and found out that she was pregnant. But inside, important processes are already in full swing, which can be tracked week by week.
5 week
From the first day of the delay in the next menstruation, a woman begins the fifth week. The embryogenesis of fetuses is in full swing - both babies are simultaneously in the process of laying the heart, kidneys, liver, there is a chord. By the end of the week, you can visit the ultrasound office and during the examination with a transvaginal sensor, you can hear the heartbeat. Two hearts will beat, but for now it will be difficult to hear it, because the heartbeat of one child in such a short period is very irregular, confused.
If the twins are dichorial and diamniotic, an experienced doctor on an ultrasound scan will already be able to detect two fetal eggs. Identical twins prefer to remain in secret for now - only one fertilized egg is visible.
6 week
The "interesting position" is already obvious to the mother - she did a test or donated blood for hCG, and received positive results. Fruit growth is approximately 4 mm. The formation of the organs of the immune system begins, the thymus gland is laid in each of the twins. In babies, handles are formed, which are still similar to fins, dark dots are formed on the sides of the head - these are future eyes, and small dents are future ears. The embryos are still motionless.
7 week
Babies are growing rapidly. This week, their growth is approaching 7-8 mm, and their weight is one and a half grams. The formation of the nervous system begins. New nerve fibers cause the embryos to move reflexively. The formation of the eyes and optic nerves began. A single intestine in each of the fruits is divided into sections, forming the digestive tract. In embryos, regardless of whether they are twins or twins, the pancreas simultaneously begins to produce their own insulin. The laying of the external genital organs begins. Embryos can bend and unbend.
This week, severe toxicosis may begin, because the uteroplacental blood flow starts. Twins with a single placenta from this week can start growing at different rates.
If before that they increased in height and weight about the same, now one of the children can "take" more food and oxygen for itself than the second, and soon in such a "duet" differences in height-weight will be outlined.
8 week
The neural tubes of children are divided into the brain and spinal cord. The twins learned to move their heads. Growth is in the range of 2-2.3 cm, tiny faces are formed, legs are formed, which are still shorter than the arms, but there are already knee joints on these tiny legs.
9 week
Babies begin to differ in size from their peers, which other pregnant women carry in a single copy. The difference in height is now about 2 millimeters, and in weight - a whole gram. Each of the twins now weighs about 5 grams and is 2.8 centimeters tall.
Babies are starting to look like human beings. The embryonic tails are reduced, each has two arms, two legs, a large head. The period of organ laying has ended, and this week ends the period of organogenesis. The last to form are the rudiments of the teeth.
Children learned to open their mouths, clench their hands into fists. Each baby develops its own blood cells. The placenta becomes more complete and takes on all the responsibilities of transporting oxygen and nutrients to children and removing metabolic products from them. Needless to say, two placentas do this job better than one.
10 week
Your twins have ceased to be embryos, now babies are fetuses, and will remain so until the very birth. Now they have mastered new movements and are learning to move their arms. Babies begin to swallow amniotic fluid, write. Both have formed necks, now each of your children can turn their heads to the sides.
Faces become more human: there are lips, eyelids, nose and ears. Hair begins to grow on the head, and thin, colorless lanugo hairs begin to grow on the body, which, together with a cheese-like lubricant, will protect the skin until the skin becomes stronger, four-layer.
The bone begins to harden. The need for calcium increases significantly.
11 week
So far, the lag behind singleton peers is not so significant in growth. As before, babies, of whom there are two in the womb, are less than single fetuses in a singleton pregnancy by 0.2 cm, but the difference in weight is already significant: each of the twins now weigh about 12 grams, while single fruits have already reached a weight of 14.5-15 grams.
Malformations are no longer threatening, the most dangerous time is over. The growth and formation of the functions of internal organs begins - system genesis. On ultrasound, it is already clearly visible which of the fruits is larger. It is still difficult to consider the sex, the process of formation of external organs continues.
The kids have learned to grab, suck, swallow. These reflexes are considered basic. The eyes move from the lateral surfaces of the heads to the center of the face. Both twins were taught to yawn.
12 week
Your crumbs already weigh about 20 grams, which is less than the weight of one fetus in a singleton pregnancy, by about 2 grams. Many people begin to actively grow their belly. This week, most of them undergo prenatal screening for congenital chromosomal abnormalities. The process of equalizing the proportions of the bodies of children begins: the heads will now grow more slowly than the rest of the bodies. The kids were taught to distinguish the tastes of amniotic fluid, and they already like the sweets eaten by their mother much more than garlic. Completed the formation of the genitals.
With some effort on the part of the doctor, it is already possible to determine the sex of the children (identical ones, as we remember, have the same sex). The accuracy of sex determination at this time is still low, it is better to wait a little longer.
13 week
The first trimester of pregnancy ends. Together with it, toxicosis decreases, if it was. Babies are very thin, red and wrinkled, like dried fruits. There is no subcutaneous fatty tissue, and therefore all blood vessels are visible through the skin.
Babies begin to hear, or rather, perceive the vibration of sound waves. It is still far from full hearing. The brain substance grows, children begin to “grow wiser”. Now the kids have learned to hug. Everyone can hug themselves by the shoulders, and if the twins are identical, they can hug each other.
14-15 weeks
The size of the fetus will now be more and more different from a singleton pregnancy every week, but the growth will be individual. Now all the forces of children will be thrown into growth and weight gain, the weight gain of the mother will also grow rapidly, the size of the abdomen during multiple pregnancies is already noticeably different from pregnant women with one baby. The growth of the tummy will be accompanied by different sensations.
Children have fingerprints, and even identical identical twins have different fingerprints. By the end of the 15th week, the first convolutions are formed in the brain of everyone.
16-17 weeks
The weight of each of the twins exceeded 120 grams, and their height exceeded 14 centimeters. Babies learned to move their eyes under closed eyelids, they have eyelashes. All muscles are formed and sufficiently developed. From this time, it is possible to determine with great accuracy the sex of children by ultrasound. The size of the babies almost reached the size of the placenta and slightly exceeded it. The production of subcutaneous fat begins. On ultrasound, you can already catch the external similarity of babies with their parents - facial features become individual.
If the pregnancy is not the first, you can clearly feel the movements.
18-19 weeks
At this time, primiparous women with multiple pregnancies begin to feel fetal movements. The bones have hardened enough, mineralization is almost complete. Now they will only grow. By the end of 19 weeks, each of the children can reach a weight of 270 grams with a height of 21-23 centimeters. The size of the mother's belly is already impressive, everyone can see it.
From now on, children begin to hear fully, like all people, but with an amendment to the fact that they are still in the aquatic environment. You can already read them and sing lullabies.
20-21 weeks
The middle of pregnancy is over, you can start counting down to delivery. Children weigh more than 300 grams. The set of subcutaneous fat continues, and therefore pathological thinness gradually disappears. The skin becomes firmer and the lanugo begins to fall out. In the cerebral cortex of children, a center is formed that is responsible for the perception of speech.
22-23 weeks
From this period, childbirth is considered childbirth, and not a late miscarriage, the probability of survival will be, but so far it is very small, because the weight of children has not approached 500 grams, as in a singleton pregnancy. And one baby born will have about 14% chances of surviving, while twins born at this stage have only about 6% chances of survival.
The formation of the spines is completed. Sebaceous and sweat glands began to function in each of the fetuses.
24-25 weeks
The twins' weight overcomes the 500-gram mark for the first time. The skin begins to smooth out, get rid of wrinkles and a red tint. The process of maturation of lung tissue begins, the alveoli begin to produce a surfactant - a substance without which independent breathing of children after birth will be impossible. The process of maturation of lung tissue will take place almost before delivery.Melanin production started. Children see dreams, while, according to scientists, most of the time babies are in REM sleep, in which dreams come.
26-27 weeks
The second trimester ends and the third begins. The twins' pituitary glands begin to release growth hormones. In boys, regardless of whether they are identical or different, the testicles begin to descend from the abdominal cavity into the scrotum. Visual function improves, babies begin to train the blink reflex. Those born at this time survive in 65-70% of cases.
28-29 weeks
The third trimester is the most troubling for moms with multiple pregnancies. Carrying two children is twice as difficult as carrying one, even though their weight and height are slightly different from single fetuses. By this time, the average weight of one of the two fruits approaches 1 kilogram 100 grams. Mom's bellies are already big, often you can't see your own legs.
In children, the cilia are lengthened, the cheeks are rounded. The optic nerve begins to act - if a bright light is directed at a woman's stomach, children will begin to turn away from the light. The survival rate of babies in the event of their birth is about 85-93%. The formation of all parts of the brain is completed. At 28 weeks, women with multiple pregnancies go on maternity leave.
30-31 weeks
The babies became very cramped in the uterus. They took a flexion position, bringing their legs to the stomach, tucking their arms and bending their heads to their chest. Hair, if it is destined to be dark according to the genetic program, begins to darken. The mass of the brain increases. Children reach a weight of 1.5 kilograms, the difference in monochorionic twins is already significant - one baby can weigh about 1800 grams, and the second - only 1300. Everything is individual.
In the body, oxytocin begins to be produced in small quantities, its accumulation will form a generic dominant - labor will begin at the right time. Even if this happens now, the predictions for babies are quite favorable.
32-33 week
The babies continue to gain weight, and the mother's body is actively preparing for childbirth. Training contractions intensify, oxytocin and prolactin are produced. Babies begin to move less, because they are already very cramped. From this date, you can wait for the birth at any time.
34-35 week
The calculator of the estimated fetal weight according to fetometry for mothers expecting twins no longer works - fetometry is no longer always measured accurately, and the weight of the fetus arrives depending on the state of the placenta, the type of multiple pregnancy and a host of other factors, among which heredity is not the last place.
According to reviews, it is during this period that childbirth often occurs, especially if the cervix, according to the gynecological examination, is already short, the lower back hurts regularly, the mucous plug has come off, and water has started to leak. A woman must be ready for any turn of events.
The placenta begins to age. The weight of children by the end of 35 weeks can reach 2.5 kilograms. The accumulation of surfactant continues in the lungs.
36-37 week
With a weight of about 2.7 kg, about half of all twins are born at this time. From 37 weeks, children are considered full-term, and therefore there is nothing wrong with childbirth at this time. In children, toenails and fingernails continue to grow, the amount of amniotic fluid decreases. The weight gain of each of their twins is about 50 grams per day.
From this time on, the senses of babies begin to tune in to their arrival in our world, because the environment they are destined to get into is significantly different from the one in which they live now. The adaptive mechanisms provided by nature are activated.
38-40 weeks
If you brought babies to the last half of the ninth month of pregnancy, you can say that you are lucky. According to statistics, most of the births occur at 37-38 weeks, about a third - at 38-39 weeks. Up to 40 weeks, multiple pregnancies are very rare. The weight of the babies has exceeded 3 kilograms, and there should be no fears - the babies are full-term, ready for birth.
All internal organs of twins work harmoniously, in concert. And only the lungs are still in readiness - babies will begin to breathe them after birth.
Because of the tightness inside the womb, babies begin to experience stress as they approach 39 weeks. This promotes the production of adrenaline, which at the hormonal level also helps the mother's body prepare for childbirth.
Right now, before childbirth, it is more important than ever to follow the movements, to prevent the development of hypoxia - the placenta or one placenta for two is already noticeably depleted, and therefore oxygen starvation at this time is not uncommon.
The choice of delivery tactics deserves special attention. If the pregnancy occurred naturally, proceeded without significant complications, childbirth can be natural, and this will be correct. But twins after IVF, presentation of one of the fetuses to be born first, not with the head, but with the pelvis towards the exit from the uterus, any complications during the long nine months - all these are reasons for prescribing a cesarean section. If it is shown, then it is carried out with a multiple pregnancy at 38-39 weeks (with a single pregnancy - at exactly 39 weeks).
The expectant mother needs to be sympathetic to the recommendations of doctors throughout the entire period of gestation.
During pregnancy with twins, general tests are more often necessary, because the load on the kidneys, heart and lungs of the mother is double. You will have to visit a doctor more often in the third trimester. And this should not be confusing either - since multiple pregnancies are considered difficult in any case, the procedure for its management is also special. But the joy is double.
See the next video for twin pregnancy.
