The First Trimester of Twin Pregnancy

Let’s start off by diving into the first trimester of a twin pregnancy – what you can expect for yourself, what your babies’ development looks like, and how you can set yourself up for a healthy, comfortable pregnancy.

First Trimester of Twin Pregnancy

Picture this: you’re already overjoyed at the knowledge that you’re expecting a baby, and your excitement has doubled now that you’ve become aware that you’re carrying twins!

While the news that what you thought was a single pregnancy is actually a multiples pregnancy may bring joy, it may also come with some anxiety, too. You may feel overwhelmed if you’ve never carried multiple babies at once or have never been pregnant before.

The best way to prepare yourself for your multiples pregnancy is to collect as much information as possible about what to expect when carrying twins and how the experience might differ from a single pregnancy. They may be more similar than you think!

First Trimester of Being Pregnant with Twins: What to Expect

Twin pregnancies create many of the same symptoms in expecting mothers, at least in the very early stages. If you’ve been pregnant before, you may recognize the telltale signs of nausea, fatigue, breast swelling or tenderness, and a missed menstrual period.

Whether you’re carrying two babies or one, zygotes are still so early in development at this stage that there isn’t much difference in the mother’s experience.

You likely won’t have any specific symptoms to suggest that you’re carrying multiple babies until your first or second ultrasound, where your doctor will be able to spot two babies developing in your womb.

Depending on your own physiology, you may start to “show” a bit earlier than you did in previous pregnancies or than you would if you were carrying a single baby.

First Trimester of Being Pregnant with Twins What to Expect​
Twin Development During the First Trimester​

Twin Development During the First Trimester

Early in the first trimester, your two babies will develop either as identical twins or fraternal twins. For identical twins, the original zygote splits into two and becomes two distinct embryos that share a placenta. That’s why identical twins are always the same sex and have the same physical features.

Fraternal twins are created by two separate zygotes that didn’t come from a single zygote but rather from two independently fertilized eggs. This means that fraternal twins can either be of the same sex or opposite sexes, and while they may have similar physical features, they won’t look identical.

By the end of the first trimester, the two zygotes will have become independent of one another and will start to grow alongside each other. Each baby will have its own heartbeat, brain and spinal cord, and the beginnings of fingers, toes, and facial features.

Frequently Asked Questions

Your doctor will be able to inform you of any specific steps you should take to optimize the safety and health of your pregnancy. However, it’s important for mothers carrying twins to be especially careful to eat a balanced diet full of nutrients and protein, as you have not one but two babies in your womb working hard to develop each day.

In the first trimester, there are no definitive differences between single pregnancy and twin pregnancy symptoms. Most expecting mothers don’t even know they’re having twins until their ultrasound.

However, some women pregnant with twins have reported worsened morning sickness when pregnant with twins. This may be connected to an increased level of human growth hormone present in their system.

Aside from an ultrasound result, there are no known early symptoms of twin pregnancy that are different from a single pregnancy. Some of these symptoms include a missed period, implantation bleeding, nausea, and breast tenderness.
Your doctor can detect twins in an ultrasound reading as early as 3 to 4 weeks of pregnancy.
In some cases, the positions of the babies can lead doctors to assume that their patient is carrying a single baby when, in fact, they’re carrying twins. By around 20 weeks, your doctor should know without a doubt whether you’re carrying twins or a single fetus.
Vanishing twin syndrome (VTS) is a condition in which one twin in a multiples pregnancy stops developing and is miscarried while the other continues to develop as normal. In most cases of VTS, the health of the mother and the remaining baby is unaffected, and this condition cannot be prevented or treated.
Losing one of your babies in a twin pregnancy is unlikely at between 11 and 17%, especially if neither fetus is showing any health problems.
It is possible to miscarry one of your babies during a twin pregnancy. This occurrence is uncommon and often doesn’t affect the health of the mother or the remaining fetus.
Identical twins occur when a single zygote splits into two soon after fertilization, creating fetuses that are genetically identical and share a placenta. Fraternal twins occur when two separate eggs are fertilized, creating two separate zygotes that grow in the womb alongside one another.
In some cases, women undergoing fertility treatments can intentionally increase their chances of becoming pregnant with twins. If you are trying to get pregnant without the use of treatments, however, there is no way to increase your chances of a twin pregnancy.
Identical twins occur approximately three times in every 1,000 births worldwide, while fraternal twins can occur between every 6 and 15 births per 1,000, depending on the country.
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