A Woman Can Get Pregnant When She Is Already Pregnant!

Here is that real life story of Jessica Allen, mother of two, who agreed to be a surrogate mother for a Chinese couple. 

In April 2016, by means of vitro fertilization, an embryo is produced for the Chinese couple. This then implanted in Allen's uterus. The procedure was successful and Allen soon became pregnant with the Chinese couple's baby. After six weeks, in the prenatal checkup, Allen comes to know that she is carrying twins. She feels happy for the Chinese couple as she believed the embryo divide and instead of one, the couple longing for a child, is going to bless with two babies.


Jessica Allen with her family, including the baby, conceived while she was a surrogate.

Allen gives birth to twins on December 12. She was not able to have a look at the babies.  However, the Chinese couple contacted her and show her the pics of the twins. They seems confused and wonder why the twins look distinctly different. One looks Chinese and other one with African- Caucasian features. After a DNA test, Allen comes to know the result which literally floored her. One of the twins is Allen's biological baby and the other the Chinese couple's. 

After getting out of the shock, she has to fight a long legal war to get the custody of her child who legally belongs to the Chinese couple ( who actually don't' want the baby that was not their) as she was just a surrogate mother in legal papers.  To cut a long story  short, Allen and husband finally get the custody of their child in February and named him Malachi. 

What happened here? is a million dollar question. The matter is not that complicated. Here is the answer. What happened is an extremely rare medical incident called "Superfetation". 

Yes, for your information, a woman can get pregnant when they are pregnant, resulting in twins with different gestational age, even though it is exceptionally rare. Here goes another interesting fact, the twins can have different fathers (caught!!). 

But, doesn't pregnancy stop the means of getting pregnant during pregnancy?

Yes, that's right. During pregnancy, certain biological processes set off to prevent further pregnancy during the pregnancy as most of us prefer to have sex during pregnancy. 

  • The pregnant woman's body releases certain hormones that stop the ovulation  
  • A "mucus plug" develops in the cervix that seals the uterus from outer region. This prevents sperm from making their way to the uterus. 
  • The lining of the uterus changes, so that another embryo cannot be implanted.

Irrespective of all these facts it is not impossible to get pregnant during pregnancy. Actually, there are two types of rare twin pregnancy' events;

Superfetation and Superfecundation 

What is superfetation event of twin pregnancies?

Here is all that you need to know about Superfetation:

  • Superfetation is the occurrence of twins or rather offspring with a different stage of development in the womb during the same time.
  • Superfetation is said to be common in some species of animals but is exceptionally rare in humans
  • For superfetation, a woman has to continue ovulation and the other egg released by the ovary is also fertilized, resulting in a second pregnancy. Thus, with superfetation, the two fetuses are different gestational ages, usually a couple of weeks apart.

Alison Jennings with her twin girls Grace and Lana who were conceived a week apart in

  • As the twins are conceived many days or weeks apart from two separate ovulations. They can be from two different fathers or the same father (entirely depend on mother).
  • It is also believed that the Superfetation happens more often than it is reported. More often fertilization happened below 10 days apart will go undetected as both twins, towards the end of pregnancy will be more or less attain equal growth expected in a twin pregnancy. It's only when doctors detect clear differences in the maturity (if the fertilization happens around two weeks apart), or as in Allen's case, the babies possess genetically different parents, the incident is reported.
  • The major risk associated with superfetation in humans is that the second baby is more likely will be born prematurely, with all the complications and health issues of a preemie.

What is Superfecundation event of twin pregnancies?

Superfecundation is the fertilization of two eggs from the same cycle by sperm from two separate sexual intercourse with different partners. Therefore, each child will have different fathers and the same mother. For this to happen, two things have to occur:

  • A woman has to ovulate twice (dizygotic). This is actually not so rare.  It most likely happens in more than 1 in 50-100 ovulations.  
  • A woman has to have sexual intercourse with different men within a couple of days of ovulation or one week prior to ovulation (the sperm can survive for up to 5 days). This will permit two different sperms to fertilize two different eggs.