New Study Reveals Relationship Between “Natural Killer” Cells in the Body and Placenta Accreta

What is placenta accreta?

In a normal pregnancy, the placenta is attached to the uterus until birth and is naturally expelled after the baby exits the birth canal. Placenta accreta is a condition in which the placenta is unable to properly separate from the uterus during labor and delivery because it has grown too deeply into the uterine wall. 

If undetected or not properly treated, placenta accreta can lead to severe hemorrhage, and can be life-threatening for mother and baby (1). In many cases, a hysterectomy, or the surgical removal of the uterus, is necessary. This leaves the mother unable to have future children. If placenta accreta is diagnosed early enough, complications can be prevented with a carefully-planned C-section delivery.

New research

A study published on August 2, 2019, in Science Immunology, found a link between the risk of placenta accreta and a gene mutation that prevents the formation of certain cells (2). These cells are called natural killer cells, or NK cells. They are thought to specialize in killing tumor cells, fighting off infections, and serving specific tissue areas. Uterine natural killer (uNK) cells contribute to fetal growth as well as trophoblast invasion into the decidua (the placenta’s attachment to the uterus). 

The collaborators on this study found that certain mice in a study done for another purpose were experiencing high rates of placenta accreta, which is uncommon in mice. These mice were found to incidentally carry a mutation in a protein called Gab3, which prevented normal uNK cell expansion (2). 

uNK cells usually keep the growth of fetal cells and the attachment of the placenta to the uterus in check. In these normal circumstances, trophoblast invasion continues until about 20 weeks gestation. Disrupted uNK cells were unable to halt the process of trophoblast invasion. This meant that the process of trophoblast invasion went beyond 20 weeks and the placenta attached more deeply to the uterus (2,3). Placenta accreta resulted.

What’s next?

The gene mutation Gab3 and the malfunctioning uNK cells are issues that could be discovered with tests. NK cell transplants are an option. It is possible that these tools could be used to tackle placenta accreta sooner.

However, the following limitations make it such that more research is required (3):

  • Not enough information is known regarding how to determine if NK cells are malfunctioning
  • Not enough is known about the safety of NK cell transplants
  • The impact of NK transplants specifically on pregnant women is unknown at present

About ABC Law Centers

ABC Law Centers was established to focus exclusively on birth injury cases. A “birth injury” is any type of harm to a baby that occurs just before, during, or after birth. This includes issues such as oxygen deprivation, infection, and trauma. While some children with birth injuries make a complete recovery, others develop disabilities such as cerebral palsy and epilepsy.

If a birth injury/subsequent disability could have been prevented with proper care, then it constitutes medical malpractice. Settlements from birth injury cases can cover the costs of lifelong treatment, care, and other crucial resources. 

If you believe you may have a birth injury case for your child, please contact us today to learn more. We are happy to talk to you free of any obligation or charge. In fact, clients pay nothing throughout the entire legal process unless we win. 

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Related Resources


  1. Placenta Accreta: Reiter & Walsh, P.C. Birth Injury Attorneys. (n.d.). Retrieved August 12, 2019, from
  2. Colucci, F. (2019, August 02). Placentation and antitumor immunity regulated by a scaffolding protein in NK cells. Retrieved August 12, 2019, from
  3. Ives, J. (2019, August 05). Study shows how ‘natural-killer’ cells may help women avoid placental accreta. Retrieved August 12, 2019, from

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