The embryo has become a fetus. The tail is gone and the face is getting its shape.
Now the embryo period is over – growing life is now called the fetus. Its face is beginning to look human, with a high rounded forehead and a small nose. The tail is gone.
The placenta is about to ripen, eventually taking over the nutrient supply from the carcass.
The fetus has fingers and toes that no longer fit together.
The girl’s ovaries or the boy’s testicles are developed.
The movements inside the uterus are stronger and the fetus is able to change position.
All the hormones that spin in your body probably make you tired and more easily irritated than usual. Your partner may have difficulty understanding your mood swings, so try talking about this. Many people feel a lot of concern, maybe even fear, and have thoughts about the future. If you feel good, visit the midwife together.
If you still feel nausea, then endure – the worst is usually over in a few weeks.
Read our articles on good pregnancy diet – or get tips on delicious mum drinks and snacks.
Women who turn 35 before the child is born are offered a so-called KUB test. It is early tests, in weeks 11-14, that can calculate the probability that your child has Down syndrome, for example.
The KUB test usually consists of blood tests and an ultrasound examination where the so-called neck clearance (NUPP) of the fetus is measured.
If the test shows risk factors, you can proceed with an amniotic fluid test or placenta test. However, these samples provide a small increase in risk of miscarriage.
One-egg twins and two-egg twins
In Sweden, about 1,500 twins are born a year. Of these, about one-third are single-egg twins and two-thirds are two-egg twins.
According to Statistics Sweden’s twin statistics, the number of twin births has increased by 50% over the past 10-15 years.
Infertility treatments (IVF) and women’s increased childbearing age have been important factors for this development. However, the importance of IVF treatments for the twin statistics is diminished as the technology has improved so that today it is normally only necessary to reintroduce one fertilized egg at a time.
Duckling – just as genetic
Unicorn fertilization means that a sperm fertilizes an egg which then divides and gives rise to two embryos, twins. The two children have the same genetic mass and are genetically identical. Of course, they always have the same sex.
If egg division occurs early, even during the first three to four days after fertilization, egg yolks can also have their placenta, depending on where the eggs get stuck in the uterus.
Usually, the division occurs after four to eight days and then the twins receive a common placenta.
Two-egg twins – just like ordinary siblings
Two-egg paralysis means that two eggs are fertilized by two different sperm at the same time. These twins are no more equal than ordinary siblings. These twins can be of the same or different sex, just like “regular” siblings.
The woman’s ability to release two fertile eggs at the same time is to some extent hereditary, but also occurs more often the older the woman is when she becomes pregnant.
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The children each have their placenta, but depending on how they lie in the uterus, the two placenta can “grow together” and be perceived as one.
DNA analysis takes time
Without DNA analysis, it may be impossible to determine if the eggs are one or two eggs, if the children are of the same sex and if there are three to four membranes between them.
Unfortunately, the analysis often takes a long time. This means that when the answer comes, the family will often know for sure whether it is one or two egg twins, just by getting to know their two children.
All fetuses are normally surrounded by two membranes, one inner thinner membrane, the so-called ovary and one outer thicker, the so-called fetal membrane. It usually also does twin fetuses. However, there are exceptions. If the division of an egg into a one-egg fertilization occurs late, the fetuses may have a common outer fetal membrane.
In those cases, only the two thin egg membranes separate the fetus, or in very rare cases no membranes at all (monoamniotic). Then it is always a question of one-eyed twins. This amounts to 25 – 30 percent of all twin pairs.
Although most twin families obviously want to know if the children are one-egg or two-egg twins, it does not matter medically what the family ties look like.
Finding out whether the twins are one-egg or two-egg is normally done by sending the placenta on analysis after the children are born. However, some factors can make it possible from the beginning to determine if the twins are one-egg or two-egg: Twin pairs consisting of a girl and a boy are always two-egg twins. Twins who have common amniotic membranes with no or only two thin membranes between themselves are always one-eyed twins.
The children’s position determines the mode of delivery
If twin number one lies with the head first, vaginal delivery is recommended. The position of twin number two does not matter. On the other hand, twin number one with the seat is first, caesarean section is usually recommended.
If twins are in the same fetal sac (so called monoamniotic) then caesarean section is recommended. These twins are usually cut a little earlier than usual, as the risk of the twins tangling in each other, or their umbilical cords, increases with time.