According to the RCOG (Royal College of Obstetricians and Gynecologists), there are currently between 1 and 2 cases of superfetation per year. It would be something like getting pregnant while already pregnant
Superfetation is defined as the multiple gestation of two or more fetuses asynchronously , that is, of different gestation times. It would be something like getting pregnant while already pregnant.
It must be distinguished from superfertilization, which is the fertilization of two or more eggs released at the same time, that is, synchronously, resulting in a pregnancy of bichorial and bianmiotic twins or triplets (each with its placenta and bag of waters). ).
How is superfetation produced?
Superfetation occurs when there is a failure in the mechanism that inhibits ovarian function during pregnancy.
- The pituitary gland is located near the brain and regulates several organs or endocrinological glands, including the ovaries .
- In a normal cycle during the first half the hormones produced in the pituitary gland stimulate the ovaries so that several of the small sacs that contain the eggs grow (follicles). Finally one of them grows more, the dominant follicle and expels the ovum at ovulation .
- If the fertilization of the egg by a sperm occurs, chorionic gonadotropin begins to be produced, which is the pregnancy hormone. Also, the production of progesterone is increased, which increases the thickness of the cervical mucus to prevent the passage of infections and more sperm, in addition to producing hormonal changes.
The increase in progesterone will inhibit the action of the pituitary gland and therefore the stimulation of the ovaries and the production of follicles with ovules. If this regulatory system fails, a new ovulation can occur and, therefore, if the woman has sexual intercourse and the sperm manage to pass the cervix and reach the ovum, a new fertilization can occur a few days after the first.
How is it diagnosed?
The diagnosis of superfetation is made during the first trimester ultrasound . They displayed two embryos with positive heart beat and right look, but different size and therefore different weeks of gestation.
The delivery of the two fetuses is carried out at the same time since it is very difficult and risky to be able to maintain the second fetus for a few more days or weeks. The route of delivery, vaginal or caesarean section, depends on the situation of each pregnant woman and the position of the babies.
And what about superfertilization?
It is defined as the production of two or more ovules in the same cycle , but at the same time and two or more of them are fertilized, so it is different.
They give rise to the so-called twins , or bichorial and bi-amniotic twins, of two different bags and placentas but occurred at the same time. Heteroparental superfertilization is less frequent. It occurs when a woman releases two or more eggs in the same cycle and has sex with two or more men on fertile days so that each egg is fertilized by a sperm from a different father.
They will be twins or triplets from the same mother, but from a different father.
What you should know:
- Superfetation occurs when there is a failure in the mechanism that inhibits ovarian function during pregnancy.
- The diagnosis of superfetation is made during the first trimester ultrasound. Two embryos with positive heartbeat and correct appearance are visualized, but of different size and, therefore, of different weeks of gestation.
- The delivery of the two fetuses is done at the same time since it is very difficult and risky to be able to maintain the second fetus for a few more days or weeks.