20 fascinating facts about twins
Discovering you’re having not one, but two babies can come as a bit of a shock. But don’t panic, here are 20 interesting facts about twins and all things twin-related.
1. Identical of fraternal?
Twins occur for two reasons. ‘Some women produce more than one egg when they ovulate. If both of those are fertilised during a cycle, fraternal, or non-identical twins are the result. Fraternal twins can run in families,’ says Dr Ella Rachamim, a paediatrician and mum of identical twin girls (bereadytoparent.com). ‘Identical twins are random. They occur when one egg is fertilised, but the embryo splits and it forms to create two babies.’ This means identical twins are always the same gender. They don’t run in families.
2. Rare twins
Fraternal and identical aren’t the only types of twin. Heteropaternal twins occur when a woman releases two eggs at once, has sex with two men and each fertilises a different egg. In superfoetation, a woman becomes pregnant with a second embryo while already carrying a fi rst one. In neither case are the babies genetic twins, but because they’re normally born at the same time they are usually thought of as such. Conjoined twins are identical twins but happen because the egg doesn’t completely split.
3. Mums of twins can get worse morning sickness.
According to Dr Roger Gadsby, founding trustee at Pregnancy Sickness Support (pregnancysicknesssupport.org.uk), this is probably caused by your immune system. It detects something ’ foreign’, causing morning sickness in any pregnancy; but because in a twin pregnancy the placenta is larger, it has a bigger ‘foreign object’ to get used to so the symptoms are worse. If this happens, Dr Gadsby says, ‘See your medical team to assess the severity of symptoms. With severe symptoms there is a chance of dehydration so you may be admitted to hospital for intravenous fl uid replacement. Safe, effective anti-sickness treatment will also be prescribed.'
4. Tall stories
Taller women have more twins. If you’re over 5ft 5in the chances go up. The reason, says US obstetrician Gary Steinman, is that taller women have higher levels of a growthrelated protein called IGF1 which affects ovaries so they are more likely to release two eggs.
5. Greater expectations
Twin pregnancies measure ahead of a single pregnancy (six to eight weeks is common) and weight gain is about 10lb more. But don’t eat for three. ‘NICE guidelines say that mums carrying twins don’t need any more calories than mums carrying one baby,’ says Helen Turier of TAMBA – the Twins and Multiple Birth Association (tamba. org.uk). ‘However, you may be more hungry than other mums. If that happens try not to fuel up on empty calories. Add something like a salad starter to meals rather than reaching for biscuits.’
A super-dark line on an early pregnancy test might say ‘twins’. Pregnancy tests detect levels of a hormone called HCG which rises after conception – and in twin pregnancies it can be about 50 per cent higher. This may mean twin pregnancies test faster and have a more intense line. It’s not a foolproof test though…
7. Long life
Mums of natural twins live longer – not because having two babies has a magical effect on health, but because the healthier you are, the more likely you are to have twins, says Dr Shannen Robson of the University of Utah. She also found mums of twins had more children overall, and were fertile longer than ‘singleton’ mums.
8. The twin age
Older women are more likely to have twins – partly because the use of fertility drugs or IVF becomes more likely, but also because of hormonal changes..
9. It helps if you expire milk sooner
‘Trying to feed two babies at once can be very tiring, but having expressed milk can help reduce some of the pressure,’ says Dr Rachamim. ‘I suggest my twin mums start expressing within one to two days of birth to help build up a supply.’ Helen Turier says it’s also important to swap your babies round when you feed. ‘One twin might feed very well, the other might be lazy, but because breastfeeding is very much about supply and demand, if you put each twin on the same breast, you may end up with an uneven supply.’ Both these experts also say you must remember that while you are the only one who can breastfeed them, someone else can wind them – and dads can bottlefeed as well as you. Don’t try to do everything.
10. The shared placenta myth
It’s often said that identical twins always share the same placenta and sac. ‘But it’s not always true – and many doctors don’t know this,’ says Dr Rachamim. ‘If the egg splits very early even identical twins can have two placenta sacs. If you think your “fraternal” twins may be identical you can check with a cheek swab DNA sample.’ The Multiple Births Foundation (multiplebirths.org.uk) can arrange this for £96.
Identical twins do have different fingerprints. They start the same but form different whorls as they're exposed to things such as different nutrient levels or touch things differently in the womb.
12. Navels help you tell indentical twins apart
Because the shape of a navel is not genetic but created when the umbilical cord falls off, it can vary between twins – some identical twins even end up with one with an innie and one with an outie. ‘You’ll quickly learn which baby is which but in those first few days when you're sleep deprived and not quite sure which ways is up, you might also want to paint the toenail of one baby so you're sure,' says Dani Diosi, doula and mum of fraternal twin girls (mamaserene.co.uk)
13. On the scent
Dogs are good at knowing who is who. In trials in the Czech Republic, highly trained police dogs were told to pick a specifi c identical twin out of a ‘scent line-up’ using sweat samples – and managed it every time. Exactly how they do it isn’t yet known but it may be something to do with immune system proteins.
14. Don't expect to reach 40 weeks
Twins are more likely to be delivered at 36-37 weeks. Twin babies weigh an average of 5lb 5oz compared to the 7lb 7oz average of single babies.
15. Remember BBPP
'It always surprises mums during a twin labour that the babies come out first, then both placentas. Most mums expect baby, placenta, baby, placenta. but once the placenta is delivered the uterus stops contracting, which is no good if there's another baby to deliver,' says Dani Diosi.
16. Twin mums sleep less
‘Without support you may fi nd it hard to get a break. Twins can also be isolating – it’s harder to get out with two. Both these factors can increase risk of PND too,’ says Dr Rachamim. ‘Ask for help. Join your local twin support network, or at least go on twin forums. Also, contact Home Start (home-start.org.uk). This scheme sends a volunteer for three hours every week – and often works with mums with twins.’
17. Twins fight less than others
They may give you more work as babies, but mums of twins may get an easier ride later, according to a study by TAMBA that showed twins had less sibling rivalry and found it easier to entertain themselves than single kids or siblings born further apart.
18. Twins learn to speak a bit later
As much as six to eight months later, say some studies. Once they do start, though, you might not understand what they say to each other: up to 40 per cent of twins create their own language. This is not evidence of genius – or anything more worrying; experts who’ve studied twin speak (aka cryptophasia) say it’s generally mispronunciation of words, or the use of words to represent something specifi c to themselves. For example, if the fi rst time twins see a cat is at the home of your friend Jen, they might call cats ‘Jens’.
19. Twins don't always skip a generation
If you’re a fraternal twin, you’re more likely to have twins yourself. It’s often said that they skip a generation, but this isn’t true. The reason why this is thought to be so is that male twins don’t ovulate and so can’t infl uence whether one or two babies are produced during conception; however they can pass the genetic susceptibility for double ovulation to their daughters, who could then have twins.
20. Hot stuff
Boobs can heat to different temperatures when cuddling twins. Studies at Case Western Reserve Univeristy in Ohio found this quirky little fact. They measured what happened to breast temperature when mums were offering 'kangaroo care' skin-to-skin contact for two babies at a time and found that each breast adjusted its temperature individually to help both babies reach around 37 degrees.