Desperate Lies’ Heteropaternal Superfecundation Exists and Is Rare

Desperate Lies' Heteropaternal Superfecundation

The series – Desperate Lies, which premiered on Netflix this Friday (5th), tells the story of a woman who becomes pregnant with twins from different fathers. Experts explain how this type of pregnancy occurs.

The Brazilian melodramatic production “Desperate Lies,” starring Juliana Paes (Liana) and Vladimir Brichta (Tomás), premiered on Netflix this Friday (5th). The plot is a fiction about a woman who becomes pregnant with twins but discovers that they have different fathers. This condition exists and is known as heteropaternal superfecundation, a very rare type of pregnancy.

“Heteropaternal superfecundation is a rare phenomenon where fraternal (non-identical) twins have different biological fathers. This process occurs when a woman releases two or more eggs during the same menstrual cycle, and these eggs are fertilized by sperm from different sexual partners,” explains Paula Marin, gynecologist and specialist in human reproduction.

This type of pregnancy is considered rare. A study by the International Society for Twin Studies found three cases of heteropaternal superfecundation in a database of 39,000 paternity tests. Additionally, the study showed that the frequency of this type of pregnancy among dizygotic (formed from two eggs) twins involved in paternity cases is 2.4%.

How Does Heteropaternal Superfecundation Occur?

According to Fernando Prado, gynecologist, obstetrician, and specialist in Human Reproduction and clinical director at Neo Vita, heteropaternal superfecundation is a rare condition because the ovulation of two eggs in the same menstrual cycle is uncommon.

“Normally, the human species releases only one egg per menstrual cycle. So, it is very rare for two eggs to be ovulated, but it can occasionally happen,” explains the specialist. “Moreover, the woman must have had sexual intercourse with two different men for each sperm to fertilize different eggs. So, the conditions are indeed quite rare,” he adds.

This type of fertilization can occur naturally when a woman has sexual intercourse with two different men within a specific period. “For heteropaternal superfecundation to occur naturally, sexual intercourse with different partners must happen within the woman’s fertile period, a relatively short window of about six days,” explains Marin.

According to the gynecologist, sperm can survive in the female reproductive tract for up to five days, while the egg remains viable for about 12 to 24 hours after ovulation. Therefore, intercourse with different partners must occur within approximately one week.

Superfecundation Can Also Occur in In Vitro Fertilization, but It Is Not Permitted

This type of fertilization can also happen through assisted reproduction techniques, such as in vitro fertilization (IVF). In this case, a woman’s eggs are fertilized by sperm from different donors or partners during the same treatment cycle.

However, according to the 2022 Resolution of the Federal Council of Medicine (CFM), in the case of embryos formed by gametes from different patients or donors, the embryo transfer must be performed with embryos from a single origin for the safety of the offspring and traceability. “In other words, this pregnancy of non-identical twins with different biological fathers cannot happen,” says Marin.

How to Determine If Twins Have Different Fathers?

According to Prado, a DNA test is the best way to determine the paternity of twins when there is a suspicion that the siblings have different fathers. “Unless they have very different racial characteristics that can be identified at birth,” says the gynecologist. The test compares the genetic material of the twins with that of the potential fathers to determine paternity.

The DNA test can be performed both after birth and during pregnancy through amniocentesis or chorionic villus sampling (analysis of fetal cells from the amniotic fluid or placenta). “However, this is a very risky test, and we usually do not recommend performing it during pregnancy. It is advised to wait until the children are born,” he says.

Are There Risks for the Mother or the Babies?

According to Marin, heteropaternal superfecundation does not present specific additional risks for the mother or the babies compared to a common twin pregnancy.

“However, twin pregnancies, in general, can be more complicated and require more rigorous medical monitoring due to the increased risks of premature birth, low birth weight, and other gestational complications,” says the gynecologist.

The miniseries “Desperate Lies” is produced by A Fábrica and also features Felipe Abib, Palomma Duarte, João Vitti, Jussara Freire, Martha Nowill, and Antonio Grassi in the cast.

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