If you're expecting more than one baby, such as twins, you have a multiple pregnancy. Here's what to know when you're getting ready for twins or other multiples.

How multiples are made

Sometimes a twin or triplet pregnancy just happens. Other times, specific factors are at play. For example, a twin pregnancy is more likely as you get older. That's because hormonal changes can cause an ovary to release more than one egg at a time. Use of fertility treatments such as in vitro fertilization to become pregnant also raises the odds of twins or other multiples.

Fraternal twins — the most common kind of twins — form when two different sperm fertilize two separate eggs. The twins grow and develop inside two separate fluid-filled sacs called amniotic and chorionic sacs. And they receive oxygen and nutrients through two separate pregnancy organs in the womb called placentas. Fraternal twins can be of the same sex or different sexes.

Identical twins form when a single fertilized egg splits early in pregnancy and develops into two fetuses. Identical twins might share a placenta and an amniotic and chorionic sac. Or the twins might share a placenta and each have separate sacs. Both have the same genetic material. They'll be the same sex and share the same traits such as blood type, hair color and eye color. Rarely, identical twins are born with connected body parts or organs. These are known as conjoined twins.

In a pregnancy of three or more, the babies may be identical, fraternal or a mix of both.

Spotting a twin pregnancy

Healthcare professionals find most twin or multiple pregnancies during an ultrasound. This test uses sound waves to make images you can see on a screen.

Sometimes, a twin pregnancy that seems typical early on is later found to be a single pregnancy. This is known as vanishing twin syndrome. For expecting parents, it can be heartbreaking, frustrating and confusing. Often, there's no clear reason for the loss.

What multiples mean for you

Taking care of yourself is the best way to have a healthy pregnancy. If you're carrying multiples, you can expect:

• More-frequent checkups. You'll see your healthcare professional often to track the multiples' growth and development during pregnancy, and to track your health. Your healthcare team also watches for symptoms of premature labor. That's because birth before 37 weeks is the most common risk of a multiple pregnancy. You might need frequent ultrasounds or other tests, especially as the pregnancy progresses.
• More weight gain. Gaining the right amount of weight is important. For twins, the recommendation usually is 37 to 54 pounds (about 17 to 25 kilograms) for people who have a healthy weight before pregnancy. Most often, you can gain that amount of weight by eating an extra 600 calories a day. But ask your healthcare professional what amount of weight gain is right for you and how many extra calories you need.
• Earlier delivery. If labor doesn't start on its own at a certain point in the third trimester, your healthcare team may recommend steps to start labor, called induced labor. This may lower the risk of certain health issues called complications. Your healthcare team can use medicine or other methods to start labor. Or your team may recommend delivery through a small cut into the lower abdomen and uterus. This is called a C-section.

Risks of a multiple pregnancy

Healthy multiples are born every day. Still, it's important to be aware of complications that can happen. Complications can include:

• Premature birth. The more multiples you're carrying, the less likely it is for your pregnancy to go to full term. If you have symptoms of preterm labor, you might be given shots of a steroid medicine to speed lung development. Even then, there could be complications after the babies are born, including trouble breathing and eating, vision conditions and infections. Treatments to prolong pregnancy, such as bedrest, aren't recommended. These methods haven't been proved to lessen disease and death in newborns.
• Gestational diabetes. If you're carrying multiples, your risk of diabetes that starts during pregnancy is higher. Gestational diabetes causes high blood sugar that can affect your pregnancy. Your healthcare team can help you learn to manage your blood sugar. You might meet with a doctor called an endocrinologist who treats hormonal conditions, a registered dietitian and a diabetes educator.
• High blood pressure. If you're carrying multiples, your risk of high blood pressure conditions during pregnancy is higher. One type of blood pressure condition is called preeclampsia. It can cause damage to organs such as the kidney and liver in a pregnant person. Some pregnant people with preeclampsia need to have their babies delivered early.
• C-section delivery. For twins, vaginal delivery often is possible if the first twin is in a head-down position. If not, you may need a C-section. Sometimes, complications after the vaginal delivery of the first twin might mean the pregnant person needs a C-section to deliver the second twin safely. For three or more multiples, it's very common to need a C-section.
• Twin-twin transfusion. With identical twins, blood vessels in a shared placenta can cause one twin to receive too much blood and the other too little. This is a serious complication for both. It may lead to heart complications and the need for treatment while you're still pregnant.

Caring for multiples

Healthy multiples have the same needs as other newborns. But you might need more rest and support than you imagined. That's especially true if your babies are born early or need special healthcare after birth.

You're also at higher risk of depression after pregnancy, called postpartum depression. Symptoms include intense sadness, anxiety or despair. Talk with your healthcare professional if you have any of these symptoms.

As you take care of your newborns, be sure to ask friends, loved ones and others for help when you need it.

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Dec. 17, 2024 See more In-depth