If you're having a twin pregnancy or other multiples, here's what you need to know to take good care of yourself — and your babies.

Sometimes a twin or triplet pregnancy just happens. In other cases, specific factors are at play. For example, a twin pregnancy is more likely as you get older because hormonal changes can cause more than one egg to be released at a time. Use of assisted reproductive technologies — such as in vitro fertilization — also increases the odds of twins or other multiples.

Fraternal twins — the most common kind of twins — occur when two separate eggs are fertilized by two different sperm. Each twin has his or her own placenta and amniotic sac. The twins can be two girls, two boys, or a boy and a girl.

Identical twins occur when a single fertilized egg splits and develops into two fetuses. Identical twins might share a placenta and an amniotic sac or the twins might share a placenta and each have separate amniotic sacs. Genetically, the two babies are identical. They'll be the same sex and share physical traits and characteristics. Rarely, identical twins fail to completely separate into two individuals. These babies are known as conjoined twins.

Triplets and other higher order multiples can be identical, fraternal or a combination of both.

Most twin or multiple pregnancies are discovered during an ultrasound. During this exam, sound waves are used to create images of your uterus and baby — or babies.

Sometimes a seemingly normal twin pregnancy is later found to have only one baby. This is known as vanishing twin syndrome. Such an episode can be heartbreaking, frustrating and confusing. Often, there's no clear explanation for the loss.

Taking care of yourself is the best way to take care of your babies. If you're carrying multiples, you can expect:

• More-frequent checkups. You'll see your health care provider often to track your babies' growth and development, monitor your health, and watch for signs of preterm labor. You might need frequent ultrasounds or other tests, especially as your pregnancy progresses.
• More weight gain. Gaining the right amount of weight can support your babies' health. For twins, the recommendation is typically 37 to 54 pounds (about 17 to 25 kilograms) for women who have a normal weight before pregnancy. This can typically be accomplished by eating an extra 600 calories a day. Work with your health care provider to determine what's right for you.
• Earlier delivery. If labor doesn't start on its own first, your health care provider might recommend labor induction or a C-section at a certain point in your third trimester to decrease the risk of complications in the third trimester.

Healthy multiples are born every day. Still, it's important to be aware of possible complications. For example:

• Premature birth. The more babies you're carrying, the less likely you are to carry your pregnancy to term. If you have signs of preterm labor, you might be given injections of a steroid medication to speed your babies' lung development. Even then, your baby might experience complications, including breathing and digestive difficulties, vision problems, and infection. Interventions to prolong pregnancy, such as bedrest, aren't recommended because they haven't been proved to decrease disease and death in newborns.
• Gestational diabetes. If you're carrying multiples, you're at increased risk of gestational diabetes. This condition causes high blood sugar that can affect your pregnancy and your babies' health. An endocrinologist, a registered dietitian or a diabetes educator can help you learn to manage your blood sugar level during your pregnancy.
• High blood pressure. If you're carrying multiples, you're at increased risk of developing high blood pressure disorders during pregnancy.
• C-section delivery. For twins, vaginal delivery is often possible if the first baby is in a head-down position. If not, a C-section might be recommended. In some cases, complications after the vaginal delivery of the first twin might require a C-section delivery for the second twin. For higher order multiples, the more common route of delivery is a C-section.
• Twin-twin transfusion. With identical twins, it's possible for a blood vessel in a shared placenta to result in one baby receiving too much blood and the other too little. This is a serious complication for both babies that might result in heart complications and the need for fetal procedures while you're still pregnant.

Healthy multiples have the same needs as other newborns. But you might need more rest and support than you imagined, especially if your babies are born prematurely or need special medical care after birth. You're also at higher risk of postpartum depression. If you experience any symptoms of postpartum depression, talk to your doctor.

Take time to enjoy your babies — and ask friends, loved ones and others for help when you need it.