Can placenta sharing change during pregnancy?

No, the type of placenta is determined very early in pregnancy. However, its functions may alter, and this is why doctors keep a close eye.

Does sharing a placenta mean twins will be more alike?

Not always, sharing of the placenta only affects the health more than genetics, but identical twins will have the same DNA.

When should I see a doctor immediately if twins share a placenta?

If you observe sudden swelling, less foetal activity, significant stomach pain, or rapid weight gain, you should get medical help right away. These could be signs of TTTS.

Why Some Twins Share a Placenta and Others Don’t

Twins are wonderful, but they can bring complications. Sharing a placenta impacts your baby's nutrient supply, growth, and pregnancy monitoring. Even your delivery plan may change. Knowing how it works will help you avoid issues and feel more confident at doctor visits.

What does it mean for Twins to share a Placenta?

Think of your placenta as the lifeline for your baby, as it provides oxygen, food, and removes waste. There are two types of setups that they share:

Monochorionic: Under this condition, twins share a single placenta and two separate amniotic sacs.
Dichorionic: This occurs when twins have two separate placentas and two separate amniotic sacs. This is typical for fraternal (non-identical) twins, but identical twins can also develop this way if the egg splits early enough.

It's not just medications that matter; understanding your twins' setup is crucial. Your doctor uses this information to determine how often to monitor the pregnancy, what warning signs to watch for, and when delivery may be needed. Learning about this early in pregnancy can help set clear expectations and boost your confidence throughout the journey.

Why do some Twins share a Placenta?

It mostly comes down to timing, specifically, when the fertilised egg splits. Understanding this can make it easier to follow why your doctor keeps a close eye on your pregnancy.

If the egg splits within the first three days, each twin usually grows its own placenta. This is called dichorionic.
If the split happens between days four and eight, the twins usually share a monochorionic placenta.
A split beyond day eight is less common. In that situation, the twins could share both a placenta and an amniotic sac, which is a riskier scenario.

The type of twins you are expecting also matters:

Identical twins (monozygotic): Depending on when the egg splits, they may share the same placenta or have two different ones.
Fraternal Twins (Dizygotic): These twins develop from two separate eggs fertilised by two different sperm. As a result, each has its own placenta and amniotic sac.

Are There Health Risks if Twins Share a Placenta?

If your twins share a placenta, there are a few unique risks to consider. That said, most parents go through pregnancy without serious complications. Awareness simply helps you and your care team stay ahead.

Twin-to-Twin Transfusion Syndrome (TTTS): Blood flow between the babies isn't always even. One person may receive too much, while the other may not receive enough. This happens in roughly 10 to 15 per cent of pregnancies with only one chorion.
Growth differences: One twin might grow faster than the other, which is why closer monitoring is often recommended.
Premature birth: Sharing a placenta can slightly raise the chances of early delivery.

Your doctor will closely monitor your growth and fluid levels with regular ultrasounds. If you notice changes early, you'll have a clear plan for taking care of yourself, rather than always worrying.

How Can You Tell if Your Twins Share a Placenta?

This isn’t something you can figure out on your own. Doctors rely on ultrasounds, usually between weeks 11 and 14. During these scans, your doctor will check:

How many placentas are there?
If the babies have their own amniotic sacs.
If they share a placenta, some early indicators of TTTS.

Sometimes, you need more than one scan to be certain, but once you are, your care plan can be adjusted to match your needs.

What Can You Expect During Pregnancy With Shared or Separate Placentas?

Your pregnancy journey will look a bit different depending on whether your twins share a placenta.

Monitoring: If your twins are monochorionic (sharing one placenta), you’ll likely have ultrasounds every 2–3 weeks, and possibly weekly later on due to higher risks. If your twins are dichorionic (each with their own placenta), ultrasounds are usually scheduled every 3–4 weeks, which is still more frequent than a typical singleton pregnancy.
Delivery planning: If your twins share a placenta, your doctor might suggest planning for an earlier delivery, especially if any issues come up during your pregnancy.
Nutrition and lifestyle: Consuming a balanced diet rich in protein, iron, and folic acid can make a significant difference. Staying hydrated and following safe, gentle exercise routines approved by your doctor will also support a smoother pregnancy.

Emotional and Social Considerations

If you’re worried about whether your babies share a placenta, that’s completely normal. Taking care of your emotional well-being is just as important as looking after your body. Expecting twins is amazing, but it can also feel overwhelming.

Rely on your partner: Bring them to appointments and involve them in discussions. Having someone by your side can make a big difference and ease the pressure.
Strengthen your bond: Connect with your baby by reading to them, listening to their stories, and engaging in conversation.

The more you support your emotional health, the more confident and calm you’ll feel as you move through the ups and downs of pregnancy.
When the fertilised egg separates, it determines whether your twins share a placenta. While identical twins may share a placenta, fraternal twins usually have different placentas. Sharing one means you'll require closer monitoring, not that your pregnancy will be complicated.
By focusing on your health, following your doctor's recommendations, and managing your emotions, you can have a smoother pregnancy. Above all, you'll be ready to joyfully and confidently raise them. Your best instrument is knowledge. If you understand placenta sharing, you'll feel powerful on this particular journey.

Whether you’re pregnant, a new mom, or navigating postpartum, you don’t have to do it alone. Join our support group to connect, share, and support one another.

FAQs on Why Some Twins Share a Placenta and Others Don’t

Can placenta sharing change during pregnancy?
No, the type of placenta is determined very early in pregnancy. However, its functions may alter, and this is why doctors keep a close eye.
Does sharing a placenta mean twins will be more alike?
Not always, sharing of the placenta only affects the health more than genetics, but identical twins will have the same DNA.
When should I see a doctor immediately if twins share a placenta?
If you observe sudden swelling, less foetal activity, significant stomach pain, or rapid weight gain, you should get medical help right away. These could be signs of TTTS.