Finding out you’re expecting twins or triplets can bring equal parts excitement, surprise and a million questions. Michael Leonardi, MD, maternal-fetal medicine specialist, explains how a multiple pregnancy may differ from a single pregnancy, what your prenatal care will look like and what you can expect week by week.
How is a multiple pregnancy different?
One of the first questions many parents ask after learning they’re pregnant with twins or triplets is, “What happens now?”
Most women carrying one baby are seen about every four weeks early in pregnancy, then more frequently as their due date approaches. If you’re pregnant with twins or other multiples, you’ll likely have more frequent prenatal visits and ultrasounds, especially during the second half of pregnancy.
Exactly how often you’ll be seen depends on the type of twins you’re carrying. For example, fraternal twins or identical twins with separate placentas may have ultrasounds about every four weeks after the anatomy scan, which typically takes place around 20 weeks of pregnancy, to monitor growth.
Identical twins who share a placenta are typically monitored more closely, often with ultrasounds every two weeks beginning around 16 weeks to watch for conditions that can affect shared placentas. If you’re expecting triplets or more, your provider may recommend even more frequent monitoring.
Some parents expecting multiples may also see a maternal-fetal medicine specialist, a physician with advanced training in caring for higher-risk pregnancies.
“The vast majority of these extra visits are routine,” said Dr. Leonardi. “They’re scheduled because carrying more than one baby requires us to monitor things more closely. Many parents tell us the additional ultrasounds become one of their favorite parts of pregnancy because they get to check in on their babies more often.”
Types of Twins
While both identical and fraternal twins involve more than one baby growing at the same time, they develop in very different ways.
Identical Twins
Identical twins happen when a single fertilized egg splits into two embryos early in pregnancy. Because they come from the same egg and sperm, they share nearly identical DNA and are always the same sex.
Researchers still don’t know exactly why an embryo sometimes splits, and it’s generally considered a random event rather than something that’s inherited.
Fraternal Twins
Fraternal twins happen when two separate eggs are released during the same ovulation cycle and are each fertilized by a different sperm. They’re genetically similar to any other siblings, sharing about 50% of their DNA, and can be the same sex or different sexes.
Fraternal twins are the most common type of twin pregnancy and are more likely to occur if twins run in the mother’s family or after certain fertility treatments.
Can triplets all be identical?
Identical triplets can happen, but it’s extremely rare. This occurs when one fertilized egg splits into three embryos. More commonly, triplets are either fraternal, with three eggs being fertilized by three separate sperm, or a combination of identical and fraternal siblings. For example, one fertilized egg may split into identical twins while a second egg is fertilized separately, resulting in two identical siblings and one fraternal sibling.
Twin Pregnancy Week by Week
Every pregnancy is unique but knowing what to expect can make the weeks ahead feel a little less overwhelming. Here’s a general look at how your babies are growing, how your body may be changing and what you can expect from your prenatal care during a twin pregnancy.
Weeks 4-8
These first few weeks are often filled with plenty of questions. You may have just found out you’re pregnant or be anxiously counting down the days until your first ultrasound.
Your body: Many of the earliest twin pregnancy symptoms are similar to a single pregnancy, although some women notice more intense nausea, fatigue or breast tenderness as pregnancy hormone levels rise.
Your babies: During this stage, your babies are growing rapidly from tiny clusters of cells into embryos. Their hearts begin to develop and may start beating around six weeks.
Your appointments: If you haven’t already had your first prenatal visit, it’s likely coming soon. Many women have their first ultrasound between six and eight weeks of pregnancy. At this visit, your provider can often confirm how many babies are developing, determine whether the babies share a placenta and estimate your due date. Depending on how early the ultrasound is performed, it may be too soon to clearly see everything, and your provider may recommend another scan if more information is needed.
Weeks 9-12
By now, you’ve likely had your first ultrasound and are beginning to adjust to the exciting news that you’re expecting multiples. While your babies are growing quickly, you may also notice your pregnancy symptoms becoming more noticeable.
Your body: If you’re wondering whether it’s normal to feel this tired, the answer is yes. Many moms expecting twins experience increased fatigue, nausea and food aversions during these weeks as pregnancy hormone levels continue to rise. Some women with twins feel relatively well, while others find the first trimester especially challenging.
Your babies: During this stage, your babies grow from about the size of a raspberry to a strawberry. Their major organs continue developing, tiny fingers and toes become more defined and they’ll begin making small movements, even though it’s still too early for you to feel them.
Your appointments: If you’ve already had your first ultrasound, this stage is often focused on establishing your prenatal care plan. Your provider will explain what your appointment and ultrasound schedule may look like throughout your pregnancy. If your first ultrasound was very early, you may have a follow-up scan during this time.
Weeks 13-16
As you move into the second trimester, you may start feeling a little more like yourself again. While every pregnancy is different, many moms find this stage brings a welcome boost in energy and fewer first-trimester symptoms.
Your body: Your uterus has grown above your pelvis, and you may find your clothes fitting differently or your favorite jeans no longer buttoning comfortably. While many women start feeling more energetic during this stage, it’s also common to notice a growing appetite or occasional backaches as your body adapts to carrying your growing babies.
Your babies: Although your twins are growing side by side, each baby develops at their own pace. At this stage, your provider begins paying close attention to each baby’s individual growth, helping establish a baseline that will be compared at future ultrasounds. By the end of this stage, all of their major organs are in place, and they’re busy making tiny movements, practicing swallowing and even sucking their thumbs.
Your appointments: By this stage, you’ll likely have a good understanding of your pregnancy and your care plan. Your provider will review any screening results, check in on how you’re feeling and answer questions as you transition into the second trimester. They’ll also discuss what to expect in the coming weeks, including when you’ll begin having more frequent ultrasounds based on the type of twins you’re carrying.
Weeks 17-20
At this stage of your pregnancy, you may soon experience those first little kicks and flutters.
Your body: Many twin moms begin to notice their babies’ movements by 20 weeks, although some moms feel those first flutters a little earlier. Your bump is becoming harder to hide, and as your uterus continues to expand, you might also notice round ligament pain in your lower belly or groin, or occasional heartburn.
Your babies: Around this stage, your babies have grown enough that your provider can take a detailed look at each one’s anatomy during your ultrasound. They’ll evaluate each baby’s heart, brain, spine and other organs while also comparing how the babies are growing together. Even though they’re sharing the womb, each baby has their own unique growth pattern, movements and personality.
Your appointments: Around 18 to 22 weeks, you’ll have your anatomy scan, which is one of the most detailed ultrasounds of your pregnancy. During this appointment, your provider will take a close look at each baby’s organs, growth and development, check the placenta and amniotic fluid, and confirm that your babies are growing as expected. Depending on the type of twins you’re carrying, this may also be when your ongoing ultrasound schedule becomes more frequent.
“The anatomy scan is an exciting milestone because we get such a detailed look at each baby,” said Dr. Leonardi. “For parents expecting multiples, it also helps us establish a strong baseline so we can continue tracking each baby’s growth and development throughout the rest of the pregnancy.”
Weeks 21-27
As you settle into the second half of your pregnancy, your babies are growing quickly, and likely, so is your belly. You may also notice your prenatal visits becoming more frequent as your care team keeps a close eye on both babies’ growth and development.
Your body: It’s common to start feeling more pressure in your pelvis, have a harder time finding a comfortable sleeping position or notice that everyday activities require a little more effort. While it’s tempting to compare your bump to photos online, pregnancies with more than one baby vary tremendously. Your height, body type, muscle tone, the babies’ positions and the amount of amniotic fluid all play a role in how your belly looks.
“It’s completely normal for two women at the same stage of a twin pregnancy to look very different,” said Dr. Leonardi. “Your bump doesn’t tell us how healthy your pregnancy is. That’s why we rely on regular prenatal visits and ultrasounds to monitor your babies’ growth rather than comparing belly size.”
Your babies: Your babies are becoming more active, developing sleep and wake cycles and continuing to gain weight. By the end of this stage, their lungs, brains and nervous systems are making important strides as they prepare for life outside the womb. Your provider will not only measure how much each baby has grown, they’ll also compare the babies to one another. Small differences are completely normal, but your care team watches for larger growth differences to make sure each baby continues developing well.
Your appointments: This is when your ultrasound schedule may become more frequent. If you’re carrying identical twins who share a placenta, you’ll likely have ultrasounds every few weeks to monitor each baby’s growth and watch for conditions that can affect shared placentas.
If your twins have separate placentas, your provider will still perform ultrasounds every four weeks to monitor their growth and make sure both babies are developing as expected. These appointments also give your care team the opportunity to check your babies’ positions, measure amniotic fluid and answer any questions as you prepare for the third trimester.
Weeks 28-35
As you enter the third trimester, the finish line starts to feel a little more real. Your babies are growing rapidly and you may find yourself thinking more about labor, delivery and finally meeting your little ones.
Your body: By now, carrying two babies can be physically demanding. You may notice increased pelvic pressure, swelling, Braxton Hicks contractions and difficulty getting comfortable, especially at night. This is all normal and temporary.
Your babies: During these weeks, your babies continue gaining weight and maturing. Their lungs, brains and other vital organs are developing quickly, helping prepare them for delivery day.
Your appointments: Your provider will continue monitoring each baby’s growth, position and well-being with regular prenatal visits and ultrasounds. You’ll also begin talking more about your birth plan, including when delivery may be recommended based on the type of twins you’re carrying and how your pregnancy is progressing.
Because twins are more likely to arrive before their due date, this is also a good time to learn about the newborn services available where you plan to deliver. Choosing a hospital with an experienced Neonatal Intensive Care Unit (NICU) means specialized care is available if one or both babies need a little extra support after birth, giving you added peace of mind.
“One of the goals of these later appointments is to help families feel prepared,” said Dr. Leonardi. “We’ll talk through what to expect and make sure you have the resources and support you need for a confident delivery.”
Are complications more likely with a twin pregnancy?
Most parents expecting multiples go on to have healthy pregnancies and healthy babies, especially with regular prenatal care and close monitoring.
Because you’re growing more than one baby, your provider will watch a little more closely for conditions that are more common in multiple pregnancies, including:
- Preterm birth: Twins and triplets are more likely to arrive before their due date.
- Growth differences: Your provider will monitor each baby’s growth to make sure they’re developing appropriately.
- High blood pressure: Some women carrying multiples have a higher chance of developing pregnancy-related high blood pressure.
- Gestational diabetes: Carrying more than one baby can also increase the likelihood of developing gestational diabetes.
- Complications from shared placentas, including unequal blood flow
These possibilities are exactly why you’ll have more frequent appointments and ultrasounds throughout your pregnancy.
“Most multiple pregnancies progress very well,” said Dr. Leonardi. “Our goal with the additional monitoring is to catch any concerns early, plan for them during delivery and help give both mom and babies the healthiest pregnancy possible.”
Choosing Where to Deliver Matters
As your pregnancy progresses, it’s also worth thinking about where you want to deliver. Because twins and other multiples are more likely to arrive early, many families choose a hospital with specialized resources for both mom and baby.
A hospital with an experienced maternal-fetal medicine team, advanced labor and delivery services and a high-level NICU can provide seamless care if your pregnancy or your babies need additional support. While many twins are born healthy and never require intensive care, having those specialists available means you’re already in the right place if they’re ever needed.
“One of the best things parents can do is choose a hospital that’s prepared for every possibility,” said Dr. Leonardi. “We hope your babies won’t need specialized newborn care, but if they do, having an experienced NICU team right there means they can receive expert care immediately while allowing families to stay together as much as possible.”
Last Updated: September 14, 2026