The moment you hear "I can see two heartbeats" on the ultrasound screen, life changes instantly. Twin pregnancies are exciting, complex, and — I'll be honest — sometimes a little daunting. Whether you've just had that news or are simply curious, this post covers everything you need to know: how common twins are, the different types, what the risks really mean, and what life with two babies actually looks like.

Twins are more common than many people realise — and the rate has been climbing steadily. In Australia, around 1 in every 60 births is a twin birth. That's roughly 1.6% of all deliveries. Globally, twin rates have nearly doubled over the last 40 years, largely driven by IVF and fertility treatments (which often involve transferring multiple embryos) and the trend toward having children later in life, since older ovaries are more likely to release more than one egg at a time.

Understanding what type of twins you're carrying is one of the first and most important things we figure out — because it has a major bearing on how your pregnancy will be managed. There are two broad categories.

In obstetrics, we describe twin pregnancies using two terms: chorionicity (how many placentas) and amnionicity (how many sacs). This is usually determined by an ultrasound at 11–14 weeks. It matters enormously for risk.

All twin pregnancies carry a higher baseline risk than singletons — but the type of twins you're carrying makes a huge difference. Here's an honest breakdown.

Premature birth is the most common complication across all twin types. Around 60% of twins are born before 37 weeks, compared to about 10% of singletons. The good news is that most of these are "late preterm" (34–37 weeks) where babies generally do very well with a short stay in special care.

Twin-to-Twin Transfusion Syndrome (TTTS) affects MCDA twins — roughly 10–15% of them. Because the twins share a placenta, abnormal blood vessel connections can form, causing one twin to give too much blood to the other. One baby grows too large; the other becomes too small. It can develop rapidly and requires specialised intervention. For this reason, MCDA twins are monitored with ultrasounds every two weeks throughout pregnancy.

Selective Intrauterine Growth Restriction (sIUGR) also occurs in monochorionic pregnancies, where one twin's placental territory is smaller and the baby doesn't grow as well. Close surveillance is essential.

Cord entanglement is a serious risk unique to MCMA twins (who share both a placenta and a sac). Because there's no membrane separating them, the umbilical cords can become wrapped around each other. These pregnancies are managed very carefully — often with hospitalisation from around 28 weeks and planned delivery before 34 weeks.

Other risks across all twins include higher rates of pre-eclampsia (high blood pressure in pregnancy), gestational diabetes, anaemia, placental problems, and caesarean birth. For DCDA twins, the risk is elevated compared to a singleton but significantly lower than for monochorionic types.

The question of how twins are born depends on several factors: the type of twins, the position of the babies near term, gestational age, and individual circumstances. Many twin pregnancies are delivered by planned caesarean section — particularly monochorionic twins and cases where the first twin (Twin A) is not head-down. However, vaginal birth is absolutely possible for many DCDA twins where Twin A is in the right position, and we discuss this carefully with each patient.

Planned delivery timing also differs by type: DCDA twins are generally delivered around 37–38 weeks, MCDA twins around 36–37 weeks, and MCMA twins earlier still, around 32–34 weeks, typically in a hospital equipped for complex care.

As an obstetrician, I look after families through pregnancy and birth — but many of my twin families come back and share what life has been like. Here's an honest picture of the joys and the very real challenges.

Parents of twins consistently say the same thing: "We wouldn't have it any other way." That doesn't mean it isn't hard — it is. But most describe a kind of depth to their experience of parenthood that is profound. Twin communities are also remarkably supportive; organisations like Multiple Birth Australia run local groups and peer support networks that many families find invaluable.

If you're carrying twins, your antenatal care will look different to a singleton pregnancy — more ultrasounds, more check-ins, and a more detailed birth plan conversation. That's not cause for alarm; it's simply about making sure you and both babies are monitored with the level of attention the pregnancy deserves.

My approach is to give every twin family the information they need to feel confident and prepared — not frightened. The vast majority of twin pregnancies result in two healthy babies and a parent (or two) who are tired, overwhelmed, in love, and proud in equal measure.

If you have questions about a twin pregnancy, or want to discuss your care, I'd love to hear from you.