If a woman is pregnant, is it possible to get pregnant again? This question certainly seems impossible, but, incredible as it may seem, it is a situation that can happen. Only one in 1 million pregnancies will happen this way and this very rare condition is called superfetation.
What is Superfetation?
It is considered superfetation when an additional fetus is conceived days or even weeks after the first baby is born . A baby conceived by superfetation will usually be born on the same date as the first baby, as it is medically necessary.
In most cases, there is an induction of labor or a cesarean section , but, gestationally, one baby is “older” than the other. Superfetation is much more common among animals, among mammals, it is well documented in dogs, rabbits, kangaroos, sheep, buffaloes, horses and panthers, but it is “almost” null in humans, which nevertheless leads us to enter in the statistics.
Difference Between Common Twins and Superfetation (h2)
Superfetation differs from twin conception , where multiple eggs are released in a single cycle. This can happen naturally or be stimulated with fertility drugs.
When more than one egg is fertilized and implants in the uterus, the result is tenigotic twins, triplets or other multiples. In superfetation, they differ in maturity, having been conceived days or even weeks apart
Is Superfetation a Rare Condition?
To characterize superfetation in human beings as “rare” would be to underestimate how unusual the phenomenon is. So far, science has been able to confirm about eleven cases since 1932, the year of the first report.
Some of the pregnancy cases with these characteristics are highlighted by the age difference between babies. Still, experts have doubts about some of these cases documented in the medical literature.
On the other hand, these same specialists admit that it is not known with exact certainty how often superfetation occurs (if it occurs), because being uncommon, a case of superfetation may not be detected and reported properly, being confused with common twin pregnancies .
Difference in Size and Weight of Babies
The difference in gestational age and size can, in some cases, be attributed to a medical condition, such as fetal fetus transfusion syndrome , a condition in which two babies share the same placenta (most twins have separate placentas) due abnormal formation of important blood vessel connections, and one of the twins consumes a larger portion of nutrients.
Children of Different Parents
This results in a larger baby than the other, although in these cases they are always identical twins, while in cases of superfetation the babies will not be identical, and may even be from different parents.
This difference in sizes is called growth disagreement. Growth disagreement is not uncommon, and as noted above, it can be caused by fetal fetus transfusion syndrome .
Other possible causes of growth disagreement include congenital infection and chromosomal abnormalities. With the case of fraternal twins, it can literally be just “luck”, since genetically some babies are programmed to be bigger or smaller at birth than others.
How does Superfetation Happen?
Some scientists are still skeptical about superfetation, and believe that there must be some other explanation for the cases in which they appear to have happened. Normally, physical and hormonal changes occur after conception which makes additional conception impossible while the first pregnancy is in progress .
First and foremost, once a woman becomes pregnant, ovulation stops . After conception occurs in a normal pregnancy, the corpus luteum (and later the baby’s placenta ) releases hormones that prevent ovulation .
In addition, the lining of the uterus thickens to prevent a second embryo from attaching. Finally, the cervix forms a barrier known as the mucous plug , which is designed to protect the developing fetus from microbes that can enter the uterus of the outside world.
As well as preventing microbial infection, the mucous plug is also an effective barrier to sperm . To summarize everything that has been said before: superfetation is so improbable because three almost impossible things need to happen for this to happen:
- Ovulation should occur while the woman is already pregnant.
- The sperm must, in some way, overcome the mucous plug.
- The implantation must take place in a uterus that is no longer prepared for this.
In addition, there is no medical data available on how superfetation actually happens, not least because all we have are assumptions. However, a medical thought is that in some cases, it is possible that implantation in the case of the first embryo is delayed.
As a result, the early rise in pregnancy hormone levels is delayed and leaves room for another conception to occur.
Risks of Superfetation
If the two fetuses have different periods of gestation, there is a risk that the second fetus will be removed prematurely. As there is a higher rate of twins born prematurely in less than 37 weeks , this increases the risk for the youngest baby, leading to serious problems such as non- lung development that will cause several respiratory problems throughout his life.
However, most of the cases verified were with babies who are only 10 days to three weeks apart, and in these same cases, generally all babies were born safely, and without any health problem.
What Causes Superfetation?
The artificial fertility treatments are deemed responsible for the cases where it is believed that the superfetation occurred. Although it is not known exactly how these treatments can influence or even cause this phenomenon.
Most Known Cases of Superfetation
All cases of superfetation are strange, but some have been much more surprising. As stated earlier, the number of cases is believed to
have increased due to the number of assisted reproduction procedures performed per year.
However, we have dozens of years of records of similar cases, and it is even said that there are records in Greek mythology. Here are some cases of superfetation, or at least the most well-known and have been reported in the medical world:
1. Two babies were born five minutes apart, but the second was conceived when the mother was two months pregnant
- In the year 1960, there was a case of superfetation that was clearly about getting pregnant while I was already pregnant. A woman gave birth to two babies that the nurse thought were twins.
- However, one of the doctors present at the time of birth noted that the baby who was born five minutes before the other showed all signs of being premature. To confirm the same, the doctor performed some tests and performed an X-ray examination of the thigh bones of the two boys.
- In the reports, the doctor found that there was a marked difference in the bone age of both boys, which should not have been the case if they were twins and were born at the same time.
- The doctor realized that the baby who was born five minutes later was, in fact, a full-term baby, while the baby who was born five minutes earlier was a premature baby and was born two months before the expected delivery date. The baby that was born prematurely was, in fact, conceived while the mother was already two months pregnant with her first baby.
2. Two babies born three weeks apart in Essex
- In 2007 again in Essex in the United Kingdom, a mother gave birth to two babies who were also conceived at an interval of three weeks. The mother became pregnant again when she was three weeks pregnant with her first baby.
3. Two babies born on the same day with caesarean section in Arkansas:
- In 2009, in Arkansas, a woman conceived another baby while she was already two and a half weeks pregnant.
- Once the doctors performed the necessary tests, they confirmed that if both babies could reach their full term, they would be born almost a month away from each other.
- Both babies were born healthy by caesarean section on December 2, with one baby 15 days earlier than the other.
And in Brazil, is there a case?
At the beginning of the year (2017) an ultrasound video was released on social media . In the recording, which reached thousands of views and shares, the doctor affirms that it is a case of superfetation, in which the patient had a twin pregnancy and, three weeks later, became pregnant again.
According to him, it is possible to see the three embryos, two with the same gestational age and one with the age difference. Despite being a possible resident of the city of Barreiras in Bahia, the woman did not have her identity revealed. There is also no information about the doctor who followed the case.
Although there are many notable things that happen inside a woman’s body while she is pregnant, superfetation is one of the rarest and most surprising!
My name is Dr. Alexis Hart I am 38 years old, I am the mother of 3 beautiful children! Different ages, different phases 16 years, 12 years and 7 years. In love with motherhood since always, I found it difficult to make my dreams come true, and also some more after I was already a mother.
Since I imagined myself as a mother, in my thoughts everything seemed to be much easier and simpler than it really was, I expected to get pregnant as soon as I wished, but it wasn’t that simple. The first pregnancy was smooth, but my daughter’s birth was very troubled. Joana was born in 2002 with a weight of 2930kg and 45cm, from a very peaceful cesarean delivery but she had already been born with congenital pneumonia due to a broken bag not treated with antibiotics even before delivery.