“It’s twins Mum!” My son was exasperated as he had sent me the picture of their ultrasound with two arrows clearly pointing at two little embryos, but I had no idea what I was looking at!
The initial excitement and delight was soon dampened by concern, as I realised that the pregnancy journey for twins is considered “high risk”. I tried to find out as much as I could about twins and the possible scenarios and discovered a number of fascinating facts which I’m sharing in this blog.
My grandbabies are monochorionic twins and had Twin Anaemia-Polycythaemia Sequence (TAPS), a rare complication where small placental connections cause a slow transfer of blood from one twin to the other. Due to this higher risk, they were delivered by C-section at 32 weeks. They spent two weeks in intensive care and then a further two weeks in special care units before being allowed home at 36 weeks. It was an emotional roller coaster for the family but we were blown away by the skill and care of the NICU teams and the boys are safe and sound and growing well! I’m looking forward to discovering how they interact with each other and whether they will develop a secret “twin language"!
The number of twins is higher than ever in the UK. Thanks to fertility treatments and people having children later in life (both of which increase the chances of twins), about 1 in every 40 babies born in the UK today is a twin.
Whether you know a pair of twins, are raising them, or are simply curious, here are ten surprising facts that might just change the way you think about twins.
Even though they come from the same fertilised egg and share the same DNA, identical twins can still have small genetic differences. Mutations can occur after the embryo splits, and environmental factors in the womb can also affect how genes are expressed. This means one twin might have a slightly different birthmark, height, or even disease risk.
Even their fingerprints aren’t identical. Fingerprints are shaped by pressure, movement and amniotic fluid in the womb, so while twins’ prints may look similar, they are never exactly the same.
About 25% of identical twins are “mirror twins”, meaning one twin’s features mirror the other’s. They might have birthmarks, hair whorls or even dominant hands on opposite sides. This is thought to happen when the embryo splits slightly later than usual.
Some identical twins share a placenta while others have their own. This depends on when the fertilised egg splits during early development. Twins who share a placenta are called monochorionic, while those with separate placentas are dichorionic.
When twins share a placenta, pregnancies are monitored more closely because the babies share the same blood supply. This can sometimes lead to uneven blood flow between the babies, known as TAPS, and a higher risk of growth differences or early birth, so doctors usually carry out more frequent scans.
Most twins arrive earlier than single babies. The average twin pregnancy lasts around 36 weeks, compared to about 40 weeks for a single baby pregnancy.
Because they share space in the uterus, twins are often smaller at birth. Doctors may recommend planned delivery around 36–37 weeks to reduce the risk of complications.
Twins are more likely to be born by caesarean section because of the increased chance of complications. However, many twin births are still vaginal. This is more likely when the first baby is in a head down position close to the due date.
Twin births usually take place in hospitals with a larger medical team present. There may be two midwives, an obstetrician and two paediatricians ready to check each baby after birth.
Many parents are surprised to learn that twins, and even triplets, can be exclusively breastfed.
Milk supply works on a simple principle: the more milk that is removed, the more your body produces. With two babies feeding, your body simply increases production. Feeding frequently in the early weeks and getting support with positioning and latch can really help establish a good supply.
If twins arrive early or need time in neonatal care, parents are often encouraged to start expressing milk soon after birth. Expressing little and often helps mimic a baby’s natural feeding pattern and supports milk production until babies are ready to feed at the breast.
Ultrasound studies show that twins begin interacting in the womb as early as 14 weeks of pregnancy. Researchers have observed them intentionally reaching out to touch each other’s faces and bodies.
Babies also become familiar with sounds they hear before birth. Twin babies spend months listening to each other’s movements, heartbeats and noises, which means they may recognise and respond to their sibling almost immediately after they’re born.
Many parents worry that twins will constantly wake each other up. But interestingly, twin babies often become used to their sibling’s noises while still in the womb.
Because of this, they sometimes sleep straight through each other’s cries. In some neonatal units, twins are even encouraged to sleep close together because the familiar sounds can be soothing.
Some studies have observed twin babies touching, patting or leaning toward their sibling when they cry, suggesting early signs of empathy and connection.
Twins also sometimes calm down when placed together. A practice known as co-bedding, where twins are placed side by side, is sometimes used in neonatal care because the closeness can help regulate heart rate, breathing and temperature.
Some twins develop a private language known as cryptophasia, a mix of invented words, sounds and gestures that only they understand.
It’s thought that about 40% of twins show some form of twin-speak, often because they spend so much time communicating with each other before fully learning adult speech.
Twins don’t always grow at exactly the same rate in the womb. It’s quite common for one baby to be slightly bigger than the other, especially if they share a placenta or sit in different positions in the uterus. Doctors monitor this closely during pregnancy, but small differences are usually completely normal.
The same applies after birth. Even identical twins can reach milestones at slightly different times, one might crawl or talk first. This simply reflects differences in personality, environment and development.
Are you a twin? Do you know twins? Are there any fascinating twin facts we’ve missed?
