Article updated on June 5, 2018

I know that it’s not always easy to understand what the doctor is telling you about your placenta during your 20-week ultrasound. They might say that it’s marginal, or low-lying, or partial previa or complete previa. But what do these terms mean?

You have to start from the start of your pregnancy. When the fertilised egg nests in the endometrium of the uterus, the placenta is formed. This allows for the maternal-fetal circulation required for the baby’s growth and proper evolution of the pregnancy. However, there are several places where the placenta can develop, depending on where it was implanted.

During the 20-week ultrasound, the doctor will check where your placenta is located to advise the caregiver who is monitoring your pregnancy, preventing certain complications if necessary. Your placenta might be at the bottom of the uterus (lower segment), which is called a low-lying placenta. If it implants very close to the cervix opening, it’s called marginal (right at the edge of the cervix). It can also be found partially in the cervix opening, and a partial previa will be diagnosed, while if it covers the whole cervix, your placenta is complete previa.

The poor positioning of the placenta isn’t hereditary or associated with family history, nor will it automatically reoccur during a future pregnancy.

If you’re faced with one of these situations, you shouldn’t be surprised if the doctor gives you clear instructions in case of bleeding. If the cervix starts to dilate, you can expect bleeding for mothers where the placenta is very close to or above the cervix. As a precaution, the ultrasound technician will suggest doing the same exam at 30–32 weeks pregnant to check if the placenta has moved as the pregnancy advances. This is usual in 90% of cases. Following this ultrasound, your attending physician will check to see if you can deliver vaginally or if a caesarian is preferable to avoid the risk of the placenta detaching and hemorrhaging. If a caesarian is judged necessary, it will be planned for around 38 weeks of pregnancy or before, depending on the symptoms.

You should understand that the poor positioning of the placenta isn’t hereditary or associated with family history, nor will it automatically happen again during a future pregnancy.

What remains important is that you take care of yourself, because when you do, you indirectly take care of your baby.

After a vaginal birth or cesarean, the placenta will be removed and handled like human anatomical waste, biomedical waste that needs to be incinerated. This is due to transmission risks for certain illnesses such as HIV, Hepatitis B or C, and other bacterial or viral infections. That is why many hospital centres, following their internal regulations, will refuse to give the placenta to families if they ask for it.

Other complications (other than poor positioning and possible bleeding) can find their origins in the placenta. Pre-eclampsia, placental detachment, low birth weight and late fetal loss are all potential consequences relating to the state of the placenta and how it’s working. One pregnancy in six will have problems associated with the placenta.

Please write to me if you have questions or comments! I might be able to help…

Talk soon,

The Baby Expert

2 Comments. Leave new

  • Hello to you, first, I just want to say that I am wholeheartedly with you. Reading this,
    it is preferable to ask your doctor for the instructions to follow up in your personal situation.
    (It might be a rest, a semi-active lifestyle, being off work, etc.) Your doctor is the best person
    to advise you. I wish you the best for the future, Marie

  • Hello Marie thank you for explaining this very clear I went for a 8 weeks scan due to little bleeding the scan picked up I had small subchorionic haematology 14x15mm so advice that on my dating scan at 12 weeks came back normal NT but placental lakes noted most prominent 23x14mm and advise to go A&E bleeding but last week I was bleeding very heavy with cloths for 2 days and had scan baby was fine and since then I have been spotting and light pinkesh discharge Coming out and oil brown blood what should I do i am currently 14 weeks pregnant should I be worried ?

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