Two heartbeats on the ultrasound. Maybe you were surprised, maybe you had a feeling. Either way — finding out you're expecting twins turns everything you thought you knew about pregnancy upside down.
Here you'll find a thorough overview of what a twin pregnancy involves, what prenatal care to expect, and how to best prepare.
How Common Are Twins?
Twins occur in approximately 1 in 80 pregnancies worldwide. The rate has increased over recent decades, primarily because:
- More women are having children later (age over 35 increases the chances)
- Fertility treatments such as IVF lead to more multiple pregnancies
- Hereditary factors play a role — twins can run in families
Identical twins occur spontaneously and affect everyone equally (about 3–4 per 1,000 births). Fraternal twins, however, are influenced by genetics, age, and fertility treatment.
Identical vs. Fraternal Twins
There are two main types of twins, and the difference matters a great deal for prenatal care:
Identical (monozygotic) twins
One fertilized egg splits in two. The babies have identical DNA, are always the same sex, and look very similar. Identical twins may share a placenta and/or amniotic sac, which affects the level of risk.
Fraternal (dizygotic) twins
Two eggs are fertilized by two sperm cells. The babies are genetically as different as any other siblings. They always have their own separate placenta and amniotic sac, and can be different sexes.
The Three Types of Twin Pregnancy
Your doctor will determine early on which type of twin pregnancy you have. This determines how closely you are monitored.
Dichorionic-diamniotic (di-di)
Each twin has its own placenta and amniotic sac. This is the most common type and carries the lowest risk. All fraternal twins are di-di, and about one-third of identical twins are as well.
Monochorionic-diamniotic (mono-di)
The twins share a placenta but each has their own amniotic sac. This applies to about two-thirds of identical twins. A shared placenta means extra monitoring because blood supply can become uneven.
Monochorionic-monoamniotic (mono-mono)
The twins share both the placenta and amniotic sac. This type is rare (about 1 percent of identical twins) and requires close medical monitoring throughout pregnancy.
In monochorionic pregnancies (shared placenta), there is a risk of twin-to-twin transfusion syndrome (TTTS), in which one twin receives too much blood and the other too little. Regular ultrasound scans catch this early.
Symptoms of a Twin Pregnancy
Many women expecting twins experience stronger symptoms than with a singleton pregnancy:
- More nausea: Higher hormone levels can cause more intense morning sickness
- Faster growth: The belly grows more quickly and becomes larger
- More fatigue: The body is working twice as hard
- Earlier fetal movement: Some feel movement as early as weeks 15–16
- Greater weight gain: Expected weight gain is 37–54 lbs (17–25 kg) vs. 25–35 lbs (11–16 kg) for a singleton pregnancy
Some women notice little difference. Every pregnancy is unique, even with twins.
Prenatal Care
Twin pregnancies receive more intensive monitoring than singleton pregnancies. You will typically be referred to a specialist or maternal-fetal medicine unit for additional appointments.
Di-di twins
- Ultrasound every 4 weeks from week 16
- Standard prenatal visits in addition
- Planned delivery around weeks 37–38
Mono-di twins
- Ultrasound every 2 weeks from week 16
- Special focus on growth differences and amniotic fluid levels
- Planned delivery around weeks 36–37
Mono-mono twins
- Very frequent monitoring, often with hospital admission toward the end
- Planned cesarean section around weeks 32–34
All hospitals with labor and delivery units can manage twin pregnancies. For mono-mono twins or complications, you will be referred to a center with specialized expertise in high-risk obstetrics.
Nutrition and Health
Your body needs extra nutrients when building two babies. Here are the most important guidelines:
Calories: You need approximately 600 extra calories per day (vs. 300 for a singleton pregnancy). Choose nutrient-dense foods over empty calories.
Iron: Your need increases as blood volume grows more than usual. Many women need iron supplements. Follow up with blood tests.
Folic acid: Extra folic acid is recommended throughout the entire pregnancy, not just the first weeks. Talk to your doctor about the right dosage.
Protein: Aim for 80–100 grams of protein per day to support the growth of two babies. Meat, fish, eggs, legumes, and dairy products are good sources.
Fluids: Drink plenty of water. Increased blood volume and amniotic fluid for two means the body needs more fluid.
Common Challenges
Rest and sick leave
Many women with a twin pregnancy need to step back from work earlier than with a singleton pregnancy. The body carries extra weight, and fatigue and discomfort can make work difficult.
Talk to your midwife or doctor early if you feel your body needs more rest. There is no shame in taking time off — your body is doing double the work.
Preterm birth
The risk of preterm birth is higher with a twin pregnancy. About half of twins are born before week 37. Most do well, but it's helpful to know the signs of preterm labor:
- Regular contractions before week 37
- Pressure sensation downward
- Change in discharge (watery or bloody)
- Back pain that comes and goes
Contact your labor and delivery unit immediately if you experience regular contractions or your water breaks before your due date. Early treatment can delay delivery.
Preeclampsia and gestational diabetes
The risk of both preeclampsia and gestational diabetes is somewhat higher with a twin pregnancy. Regular check-ups catch these early.
The Birth
About half of all twins are delivered by cesarean section. But vaginal birth is entirely possible with di-di twins when twin A (the one positioned lower) is head-down.
Vaginal twin birth:
- Takes place in an operating room (for readiness)
- Epidural is recommended for flexibility
- Twin B is usually born shortly after twin A
- Midwife and doctor are present throughout the birth
Cesarean section is recommended when:
- Mono-mono twins
- Twin A is in breech position
- Complications requiring rapid delivery
- Large weight difference between the twins
Twin births are often planned around weeks 36–38, depending on type. Spontaneous labor before this is also common.
Practical Preparation
Preparing for two babies requires a little extra planning. Here are the most important things:
Equipment:
- Double stroller (side-by-side or tandem)
- Two car seats
- Two cribs (or one larger bassinet to start)
- Double the clothes in newborn sizes
Help:
- Plan who can help the first weeks
- Talk with your partner about sharing night duties
- Consider accepting offers from family and friends
- Check if local social services or family support programs offer extra assistance for multiple-birth parents
Finances:
- Double expenses for diapers, clothes, and gear — but much can be bought secondhand
Many communities have twin parent groups through hospitals or volunteer organizations. Connecting with others in the same situation is invaluable.
Frequently Asked Questions
How is a twin pregnancy detected?
Most twin pregnancies are detected at the first-trimester ultrasound between weeks 11–14. Some women suspect twins due to stronger morning sickness, rapid weight gain, or a uterus larger than expected for gestational age — but ultrasound is the only reliable way to confirm it.
Can I give birth to twins vaginally?
Yes, vaginal birth is possible under favorable conditions — especially if the first twin is head-down. Your doctor will assess this individually based on the babies' positions, type of twin pregnancy, and other factors. A cesarean section may be necessary in some cases.
Do I need more prenatal care with a twin pregnancy?
Yes, twin pregnancies are monitored more closely with more frequent ultrasounds and check-ups. The type of twin pregnancy (identical or fraternal, shared or separate placentas) determines how intensive the monitoring is. Mono-mono twins require the most monitoring.
Summary
- Twins occur in approximately 1 in 80 pregnancies
- The type of twin pregnancy (di-di, mono-di, mono-mono) determines the level of care
- More frequent check-ups and ultrasounds are standard
- Nutrition, rest, and early work adjustments are often necessary
- Vaginal birth is possible under favorable conditions
- Start preparing early — most of it comes down to practical planning
A twin pregnancy demands more from your body and more attention from your healthcare team. But with good care and preparation, the vast majority of parents welcome two healthy babies.
Further Reading
- Diet and nutrition during pregnancy
- Cesarean section — what you should know
- Preterm baby at home
- Parental leave planning
- Week-by-week pregnancy guide