1, the formation of twins
(1) identical twins
In the process of division, the fertilized egg divides into two or more independent embryonic cells or cell groups, and each divided embryonic cell or cell group develops into a different individual. Twins produced by this division have the same genetic characteristics, so they have the same sex, similar personality and appearance.
(2) fraternal twins
There are two mature follicles that excrete mature eggs successively or simultaneously, and these eggs are fertilized with lotus root juice at the same time. Because embryos come from different eggs and sperm and have different genetic characteristics, babies born may have different looks and genders. This is what we call twins, and most twins (about 75%) belong to this category.
2. Factors affecting twin pregnancy
1. Incidence of twins: The birth frequency of identical twins is very stable, with little change in different races, regions and different periods. However, the birth frequency of fraternal twins varies greatly in race and region, and it has increased year by year in recent years.
2. Genetic factors: If the mother is a twin, the ratio of twins in the next generation is 1.7%. Mother's genes are more important than father's genes when deciding twins.
3. Mother's age and parity: The incidence of twins is directly proportional to the increase of mother's age and parity, especially when the mother is 40 years old or has more than 7 parity, the chances of having twins are greater.
4. Endogenous sex hormones: Spontaneous fraternal twins are related to the high concentration of endogenous follicle-stimulating hormone.
Step 3 take ovulation drugs
Oral ovulation induction drugs will greatly increase the probability of having twins, but generally healthy women only ovulate one egg every month. If ovulation drugs are artificially used to promote ovarian ovulation, the consequence is ovarian hyperstimulation syndrome, such as nausea, dizziness, impaired liver and kidney function and so on. If necessary measures are not taken in time, it will be very dangerous for both mother and child. So I want to remind you that the corresponding risk of having twins in this way is very high.
Step 4 increase hormones
The use of gonadotropin drugs can induce the secretion of gonadotropin in the anterior pituitary gland, and ovulation can be induced after medication. Most of these drugs are used to treat infertility. If healthy women want to have twins, taking these drugs may increase the probability of twins, but if they don't use them properly, they may have adverse reactions such as nausea, dizziness, fatigue, pain in the main parts, breast swelling pain, blurred vision and rash. In severe cases, it even causes cancer, and the risk index is extremely high.
Step 5 Use test-tube babies
Through ovulation induction technology to promote the development of follicles in women's ovaries, and then take out eggs from them for in vitro artificial fertilization, and then transplant the developed embryos into the uterus for pregnancy. This method is called "test-tube baby".
Because this process is carried out under the manual operation of doctors, often in order to ensure the quality of fertilized eggs, in the process of operation, a class will choose more eggs for fertilization. When they develop to a certain extent, they will choose the best 2-4 to be implanted in the mother's uterus, and finally leave the best embryos in the uterus for implantation until the baby is born. Some women's physical conditions allow two embryos to develop at the same time. At their own request, doctors can also leave two embryos in their stomachs, thus giving birth to twins.
However, the state has clear regulations on how many fertilized eggs to implant, that is, three can be implanted over the age of 35, and only two can be implanted under the age of 35.
6. Symptoms of pregnancy with twins
1, the early pregnancy reaction is stronger.
In the second month of pregnancy, expectant mothers with twins have more early pregnancy reactions such as nausea, vomiting, loss of appetite, irritability and dizziness than single mothers. Because the early symptoms of twins are more obvious, expectant mothers are also harder than single-child mothers.
2. The progesterone value and hcg value are high.
Pregnant women with twins usually have higher progesterone and hcg values in the early pregnancy than pregnant women with one child. For example, in the seventh week of pregnancy, the normal value of progesterone is 52.7- 100. 1 nmol/L, and it may be higher if it is twins. Of course, this indicator is something that expectant mothers can't intuitively feel in their lives, and can only be seen in the examination results of hospitals.
3. The uterus and abdomen are bigger than normal.
The expectant mother's uterus is too large, which is the initial symptom of carrying twins. If you are in the eighth week of pregnancy and the size of your uterus is 1 1. At this time, expectant mothers should do ultrasound to check whether they are pregnant with twins or multiple births.
The abdomen of twins is bigger, growing rapidly and obviously, exceeding the normal size of pregnancy month, especially after 24 weeks of pregnancy.
4. Hear two fetal heart sounds
With the increase of pregnancy time, if you are twins, you can touch two fetal heads and two fetal hips and hear two fetal heart sounds. Ultrasonic examination can also detect two fetal heart waves with different speeds, and X-ray examination can show the bones of two fetuses.
5. The fetus moves in different directions.
Expectant mothers can already feel the baby's fetal movement in the fifth month. If expectant mothers find fetal movements in two different directions, they should go to the hospital for examination, which is also the initial symptom of pregnancy with twins.
It will be found out in 6 or 45 days.
Generally speaking, expectant mothers can detect whether they are pregnant with twins by doing B-ultrasound after 45 days of pregnancy. B-ultrasound can see two gestational sacs as early as 7-8 weeks of pregnancy, and after 13 weeks, two fetal head auras can be clearly displayed, and the corresponding spine, trunk and limbs can be seen.