It was a shock to find out they were twins. The fact that your fetus is at a different stage of development is a completely different shock. This sounds like a plot hole in a sci-fi movie. However, it has its own term.
Heterotopic pregnancy.
The definition is easy. It occurs when a second pregnancy begins while the first is already established. 2 eggs. There are two sperms. Two different time windows. The twins weren’t the only ones who were late. This is a new pregnancy that begins after the first implantation.
How rare is that?
Very. Only about 10 cases have been recorded in human history. There is no clear consensus in the medical community about the “isolated” gestational age in such cases. The consensus is simply that there were two separate ovulation events. One of them occurs before the other.
The body resists this.
Normally, when pregnancy begins, the reproductive system stops delivering eggs. I don’t ovulate many times a month. Sometimes two eggs are released in one cycle, resulting in twins. But that’s just a period of time. Hyperovulation requires another window. Another ovulation. This happens after the first egg is fertilized and implanted.
Why does this mechanism fail?
Dr. Robert Atlas, director of obstetrics and gynecology at Mercy Medical Center in Baltimore, refers to cervical mucus problems.
“You only have 24 or even 36 hours for the cervical mucus to thin,” says Atlas. “Sperm can enter the uterus and enter it.”
When fertilization occurs, the mucus thickens. It blocks the cervix. It acts as a wall. Later, the sperm should bounce back. they should stop.
It doesn’t always work out.
This is normal in animals. cat. Panthers. Badger. Some people have multiple wombs to carry out this process. This is not the case with humans. We only have one womb. We weren’t designed that way. Even a normal multiple pregnancy carries great risks. It is more rare.
Dr. Atlas has been practicing medicine for 25 years. he has never seen it. He hoped that would never happen.
Doctors don’t immediately get susceptible when they see fetuses of different sizes on ultrasound. They look for anomalies. Measure the length from the top of the head to the butt. The distance from the top of the head to the bottom of the buttocks. This determines the gestational age. If the fetus is very small, growth restriction may occur. This is not another condition.
Does it really exist in humans?
Some experts say no.
Dr. Jim Bertoni, an expert in maternal-fetal medicine, believes that suspected cases are often misdiagnosed. “Most authorities believe that the so-called superfetation phenomenon in humans is caused by significant inequalities in the growth and development of twin fetuses of the same gestational age.”
Size differences are not the same as age differences.
Take the Prieto twins, who live in Knightdale, North Carolina. They were born 6 years ago. Mother Martha is in labor. Baby A came out normally. Baby B is not ready yet. He sits very high under the bust. Not head down. Not in the birth canal. The doctors had to suck and push him out.
But they are twins. We are the same age.
Baby B was bigger when he was born. 5 lbs., 5 oz. Baby A is small. 4 lbs 10 oz. The size difference is real. The age is also the same.
This is the most likely explanation for the small number of reported superfetation cases. Uneven growth. It’s not that time is uneven.
If that is true, what are the risks?
Researcher Dr. Steven Hausman points out this danger. Embryo in different stages of development. A person is ready to be born. The other is not. This can lead to premature birth. The baby will arrive early. Another person stays inside.
However, a small number of reported cases have had positive results. The baby is growing. Premature birth is recognized and treated. Modern medicine can control the complications.
The science is still up in the air. The body tries to stop it. The mechanism seems solid. However, these reports still exist.
There is another phenomenon that is a little less mysterious. Heteropaternal superfertilization.
This is the case when twins have different fathers. This happens when a woman releases two eggs in one cycle. She had sex with two different men over the course of a few days or weeks. Each egg is fertilized by a different sperm.
The ecology is clear. Time is running out.
Superfetation causes even more confusion. It asks for a second chance to live in the promised body. Nature requires us to stop and restart it.
we don’t know enough. There is too little data. The human body is complex. Sometimes it works wrong. In some cases, ultrasound readings may be incorrect.
The truth may lie somewhere in between. It’s somewhere between impossible and misdiagnosed. For now, it is a footnote in medical history. It is very rare. “What if?”
