Twin Pregnancy Week by Week

So, you’ve hit the jackpot—you’re pregnant with twins! While you’re adjusting to this life-changing news, your little ones are already growing and preparing to meet you! As you embark on this double adventure, it can be helpful to know about some of the common twin pregnancy symptoms that may await you week by week.

Twin Pregnancy: First Trimester

In the first few weeks of your twin pregnancy, you might notice some typical signs of early pregnancy, such as breast tenderness, fatigue, nausea, and a missed period. During your first trimester, a home pregnancy test can confirm your hunch that you're pregnant, and eventually an ultrasound scan at your healthcare provider's office will reveal you are pregnant with twins. Although the first few weeks are a little uneventful, the first few months are quite exciting! Both of your babies develop from a cluster of cells to a tiny fetus with a heart, spinal cord, head, and limbs. Read on to learn about twin pregnancy development and symptoms, week by week during the first trimester.

3 Weeks

After the first three weeks of pregnancy, you may start to feel a few pregnancy symptoms. And when it comes to a twin pregnancy, there’s quite a lot going on in that belly of yours, which is now nurturing either identical or fraternal twins.

• Identical twins. When a sperm fertilizes an egg, it becomes a single cell called a zygote, which has 46 chromosomes that determine your baby’s sex and physical traits. When you have one zygote that splits into two during early pregnancy and grows into separate embryos, you’ll have identical twins. Because they come from the same zygote, they will have the same chromosomes and be the same sex.

• Fraternal twins. If you have two zygotes, from two eggs fertilized by different sperm, these twins will not be identical and can be either the same or different sex. Fraternal twins are more common than identical twins.

4 Weeks

At around 4 weeks pregnant, some important developments occur, including implantation. This is when you may notice one of the first symptoms of pregnancy, which is implantation bleeding.

• Implantation in the uterus. Around eight or nine days after fertilization, the rapidly dividing ball of cells, now known as a blastocyst, will burrow into the lining of the uterus. Each blastocyst, two in the case of a twin pregnancy, will grow into an embryo.

• The placentas begin to grow. About one week later, the outer layer of the blastocyst will begin to form a placenta for each baby, providing nourishment over the course of your pregnancy. In some rare cases, the babies may share one placenta.

5 to 8 Weeks

When tracking pregnancy symptoms week by week, whether with one baby or twins, 5 to 8 weeks pregnant is when nausea and vomiting—aka morning sickness—might kick in. Though the precise cause or causes of this condition are unknown, the pregnancy hormone human chorionic gonadotropin (hCG) may be a contributing factor. No one loves having this unpleasant symptom, which can be (but isn’t always) more severe during a twin pregnancy, but many moms-to-be choose to think of it as a sign that their pregnancy is going well! This is important considering all the growth and development your babies are experiencing during this time:

• Your twins start forming brains and spinal cords. Around 6 weeks, your babies’ spinal cords and brains will develop from the neural tubes.

• Little arms and legs start to form. By 8 weeks of your twin pregnancy, your babies will have buds for limbs that look like little paddles.

• Two heartbeats. The tissues that form your babies’ hearts will begin to develop at this time. Heartbeats may even be detected during an ultrasound exam offered by your healthcare provider during this trimester. Ultrasound is the way most women find out they are pregnant with twins, often at around 12 weeks of pregnancy.

• All major organs take shape. By the end of 8 weeks, all your babies’ major organs will have started to develop.

9 to 13 Weeks

As you enter the final weeks of the first trimester, you may be surprised to learn what’s happening in that baby bump of yours.

• Fingers, toes, and nails begin to appear. Your tiny duo will start to develop fingers, followed by little toes taking shape; by 12 weeks, fingernails will also begin to sprout.

• Facial features take shape. Twelve weeks into your pregnancy, your twins’ faces are less broad and more defined. Your babies will have eyelids and a more developed profile, with a formed nose, eyes, and upper lip.

• Tooth buds form. Your babies’ future teeth are already in place, as tooth buds have appeared under the gums.

Your Twin Pregnancy in the Second Trimester

Twin pregnancy symptoms, when tracked week by week, aren’t too different from those in a singleton pregnancy. However, twin moms-to-be usually show their bumps sooner, and during the second trimester, it will become increasingly obvious that you’re pregnant with twins. You might also feel more uncomfortable and tired than singleton moms during this time or gain more weight, which is completely normal—after all, your body is a nourishing home to two developing babies! Read on to learn about twin pregnancy development and symptoms, week by week during the second trimester.

14 to 17 Weeks

The beginning of your second trimester is a busy time for your babies. They’re gaining weight and becoming more active. As for you, you’re entering what’s known as the golden period of pregnancy, when morning sickness and fatigue finally start to subside, and you feel more energized.

• Limbs will move. Your babies will start to jerk their arms and legs, but you probably won’t be able to feel anything until they’re a bit bigger.

• Bones start to harden. The bones of your twins will begin to harden, particularly the head and long bones.

• Little eyes may move. Although their eyes are still closed, at 16 weeks, your babies can slowly move their eyes behind the lids. Your little ones should also have eyebrows and eyelashes at this point, too.

• A protective coating forms on the skin. Your babies will start to acquire a greasy, waxy coating known as vernix, which helps shield their skin from the amniotic fluid.

18 to 22 Weeks

A few new aches and pains could crop up at this time, thanks to your growing uterus and hormonal changes. To help ease the discomfort, try adding some exercise to your daily routine, if your healthcare provider gives you the OK. Exercising while pregnant may not only minimize discomfort but also help boost your energy level and increase blood circulation, which benefits your twins.

• Your twins may suck their thumbs. Your growing duo will develop the sucking reflex and may even suck their thumbs.

• Your babies get active. During these weeks you may detect some gentle fluttering or wriggling. Before long, these movements will morph into kicks and jabs!

• Your babies can hear. By 18 weeks, your babies may even begin to hear, and their ears will begin to stand out at the side of the head.

• Your babies grow hair. Just after 20 weeks, your babies will be covered with a fine, downy protective hair called lanugo. Not only that, your little ones are also continuing to grow eyebrows and hair on their heads!

23 to 27 Weeks

You may start to develop some new symptoms as your twin pregnancy progresses week by week in the second trimester. For example, it’s possible to feel Braxton Hicks contractions, a sign that your body is practicing for labor. These practice contractions are also known as false labor, as they’re not the real deal. Your babies are also making progress and getting ready for their big entrance.

• Your twins form fingerprints. Ridges in your babies’ palms and soles are becoming fingerprints and footprints.

• Your babies can respond to sound. Your babies may begin to move in response to familiar sounds, such as your voice.

• Little lungs develop. At around 26 weeks, the lungs forming in your babies' chests are slowly preparing to make breathing motions. They are producing a substance called surfactant that helps the air sacs in the lungs stay inflated, which is necessary for breathing.

Your Twin Pregnancy in the Third Trimester

In the third trimester, some of the most common twin or singleton pregnancy symptoms that could appear week by week include backaches as well as swelling in your hands, feet, and legs. As a result, you might find it hard to sleep or walk comfortably. Meanwhile, your twins are getting ready for the big day! During this time, they’re listening to familiar sounds, such as your voice, and are likely settling into the optimal position for a vaginal delivery, which means both babies have their head down. In some cases, only one twin may be facing headfirst, or both twins are facing feet first. Check the visual below to get an idea of how your babies might settle in the womb. And keep in mind that with twin pregnancies, there’s a higher likelihood of needing a cesarean delivery or giving birth prematurely.

Although you might have checked our due date calculator, be aware that in an average twin pregnancy, twins are born closer to 35 weeks than to 40 weeks, so it’s worth getting prepared early. Make sure you have doubles of all the clothes, cribs, wipes, and diapers you’ll need! And since double the fun means double the price, earn cash and rewards by downloading the Pampers Club App.

Read on to learn about twin pregnancy development and symptoms, week by week during the third trimester.

28 to 32 Weeks

At this stage, your body is making more blood than it usually does, and your heart is pumping quickly to circulate it throughout your body. And, naturally, your baby bump continues to expand week by week, as your twins grow and develop.

• Your twins can open and close their eyes. Your twins may be able open and close their eyes and sense changes in light. However, they will spend most of their time sleeping with eyelids closed.

• Brains growing. Your babies’ brains are growing quickly at this stage of your pregnancy. Parts of the brain can now control body temperature, so your twins are not solely dependent just the temperature of the amniotic fluid to stay warm.

• Your twins have finished their major development. By now, your babies will have finished most of their development and start to gain weight rapidly. At 32 weeks, your babies may start to shed their lanugo, the fine hair that covered their bodies.

33 to 36 Weeks

As mentioned above, those who are pregnant with twins can expect an earlier delivery. So, at this point in your twin pregnancy, you’re in the home stretch, and your babies know it!

• The lungs are preparing to breathe. Your babies’ lungs are maturing and preparing to breathe outside the womb.

• Twins gaining weight. During the last few weeks of your pregnancy, your twins will continue to build fat layers and put on weight. Most twins will be born smaller than singleton babies, weighing on average 5.1 pounds.

• Getting ready for birth. Most women give birth between 37 and 42 weeks. However, if you’re expecting twins, you could give birth as early as 35 weeks, so keep an eye out for any signs of labor and discuss your options with your healthcare provider.

In the video below, watch one of our partner nurses offer advice on when to head to the hospital as the signs of labor begin.

The Bottom Line

Were you not expecting two for the price of one? After the initial surprise of a twin pregnancy, it’s completely natural to feel overjoyed, overwhelmed, or even shocked for a while! But, knowing the symptoms of a twin pregnancy and what awaits you week by week can help you feel confident along the way and offer some peace of mind. In some ways, a twin pregnancy isn’t that different than a singleton one. You’ll have a larger baby bump, of course, and you may feel more tired or experience other symptoms to a greater degree; but you’ll make similar progress as the weeks and months go by and your due date approaches. However, to summarize a few important differences, a twin pregnancy might include

• more checkups with your health provider

• increased weight gain

• an earlier delivery

• your twins needing a little extra time in the hospital

• higher risk for cesarean delivery and premature birth.

Think of it this way: though a twin pregnancy comes with its share of challenges, having twins means there are two babies to love and bring joy into your life! Hang in there and enjoy the journey as much as possible. You’ll be amazed to discover how your heart will grow twice as much!