Vital Roles Of The Placenta: When Does The Placenta Take Over?

The placenta by itself is a wonder miracle to both the developing child and the expectant mother. It serves a variety of crucial roles in ensuring that the pregnancy proceeds well and that both the child and the mother are safe. But, the placenta doesn’t take over immediately after conception and this leads us to our biggest question: when does the placenta take over?

Before looking at when the placenta takes over, it is good to ask ourselves: what the placenta is, how it is formed and its role to both the baby and the mother.

What is the placenta?

What is the placenta

Considering the fact that the placenta isn’t visible to the naked eye, out of curiosity most women would like to know what the placenta is and most importantly how it is formed.

The placenta is an organ that attaches itself to the deep lining of the uterine wall after conception. This organ acts as a linkage between the mother and the developing baby. It would be logical to say that the placenta is like the baby’s grocery store since it provides the baby will everything needed for healthy development.

How is it formed and when does the placenta take over?

Despite the fact that the placenta begins to form immediately after conception it doesn’t take over immediately. Instead, the ovary in which the ovum that got fertilized was released from collapses allowing the formation of corpus luteum which in the meanwhile performs the task that the placenta will take over later.

The corpus luteum helps in the release of progesterone hormone that is very vital for the implantation of the fertilized ovum and for the development of the uterine wall which is necessary to hold the baby as he/she begins to develop inside the womb.

As stated earlier the placenta begins to form immediately after conception. A collection of cells attach themselves to the deeper wall of the uterine wall and it is these cells that gradually and slowly develop into the placenta. Basically, the placenta is made up of blood vessels.

When does the placenta take over?

On my first pregnancy, my doctor had told me that the placenta would take over on the 12th or 13th week of my pregnancy. However, just at 9 weeks pregnant, I woke up one morning feeling refreshed. At first I didn’t figure out what the problem was but definitely, something was out of the usual I could feel it. It was until later in the day that I actually figured out that I didn’t have morning sickness. My breasts too were not sore as usual and they didn’t hurt. It felt as if all the signs and symptoms of pregnancy I had disappeared. I was so worried thinking I was about to have a miscarriage and I had to visit my doctor who did a check up and informed me that there was nothing wrong with the pregnancy it was just the placenta taking over. Finally! I got my relief.

Generally, the placenta takes over at week 12 or so but there have been reported incidences of this happening sooner at week 9 as it was with my case. And, you shall definitely know when the placenta takes over since there will be reduced morning sickness, your breast begins to get bigger and stop being sore and itchy.

Vital functions of the placenta

1. Transfer of nutrients

The placenta is very rich in blood vessels and allows the developing baby to get nutrients and oxygen from the mother’s blood stream and in turn dispose waste products and carbon dioxide from the baby’s blood stream to the mother’s blood stream.

2. Protect the baby

A developing baby may be prone to many problems. However, the placenta ensures that the baby is safe in the womb. To begin with, the blood of the mother and that of the baby do not mix, this ensures that the baby does not contract any disease from the mother's bloodstream. That’s why you can get an HIV negative baby while you are HIV positive. Also, there are incidences where the rhesus factor of the baby and the mother do not match, in this case, if the two blood would mix this would lead to agglutination and possible death of the baby.

3. Produce hormones

During pregnancy, the placenta releases a lot of hormones that are necessary for the healthy development of the baby. These hormones include progesterone hormone, oxytocin, and estrogen hormone.


As seen the placenta is very vital for the development of a healthy baby, and it is, for this reason, we should always ensure that we do not do anything that would compromise the formation of the placenta. Smoking and taking in of illegal substances can disrupt the formation of the placenta.

I hope you found this tutorial fun and most importantly knowledgeable. Most women are not aware of when the placenta takes over but you are now fully informed about it including the signs that will enable you to know that the placenta has taken over.

Don’t keep all this knowledge to yourself, share this article with a friend or two and don’t forget to leave a comment in the comment section below. Thank you.

Jennifer Shackelford

Hi, I’m Jennifer, the founder and editor of TheMamaNeeds.com. On The Mama Needs, I write about experience with pregnancy, raising kids, and nutrition for both kids and expectant moms.. I love that blogging brings parents together and lets our readers know they’re not the only ones going through these experiences. I love seeing comments on my posts that say “I thought it was just me! I’m so glad it’s not!” Being a parent is hard, but friends and blogs really help.

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