1. Feeding requires second helpings of patience

My twins were in hospital for seven weeks after their birth, as they were premature, but there were some benefits to that -- I had a lot of help from the nurses with expressing milk and getting into the feeding routines.

Nothing prepares you for the shock when you get home, though. When you're tired and you've got newborn twin babies, it's often tricky to remember which twin is which. (Unlike Knox Leon and Vivienne Marcheline Jolie-Pitt, my twins are the same sex, although not identical.)

So it's absolutely vital to keep a written record of the twins' feeding in the first few months; it also means you can chart their development.

2. Sleepless nights are doubly exhausting

When you've got twins, the lack of sleep is incredible -- there were weeks at a time, when my twins were small, when I didn't seem to get any sleep at all.

Literally, the minute your head hits the pillow it's time to get up again. It might be easier to sleep in separate bedrooms if you and your other half are disturbing each other too much.

When the twins were three months old, my husband and I decided also to split them up, because they'd wake each other up. It's very hard work, and the sleep deprivation makes it worse. There's not a lot of cooing going on!

3. You'll be grateful for an extra pair of hands

I would recommend that anyone with twins should get some help, although that's not always easy for every family because the cost of childcare is immense. It's worth, if you can afford it, getting in a maternity nurse or just someone there, so that you can have a shower or half an hour's sleep.

But getting help isn't always a miracle answer because the person helping you might have very different ideas about parenting. A baby's a baby, they don't change, but parenting conventions change all the time, which can cause conflict. I'd always recommend getting in touch with a support group and spending time with other parents of twins; it's a relief to talk to people who really know what you're going through and can offer you tips and advice.

4. Everything is twice the price

It's never cheap having children, but with twins the costs are huge, even if you're not buying anything fancy and not being wasteful. We estimate that twins cost about e75,000 in the first five years -- and that's not including getting a bigger house and a bigger car. Just feeding them and changing them, with eight feeds and eight changes a day per baby, will cost about e1,250 a year in bottles and nappies. The total cost for the first year is between e6,250 and e12,500.

However, twins tend to be born to older mothers -- who usually have a bit more money.

People think it's IVF that produces multiple births, but actually the main contributing factor is the age of the mother. You're more likely to have twins if you're over 35, and only about 25pc of multiple births are caused by any sort of assisted conception.

5. It puts pressure on your partnership

Studies have found that divorce and separation rates are much higher in couples with twins.

The strain they put on a relationship, especially in the first year, is enormous. If you're still married after a year, you're doing well! My advice is to try to keep things in perspective, although that's easier said than done. It's difficult to explain what sleep deprivation does to you if you've never been through it, but it can make the tiniest things blow up out of all proportion. My sister said to me quite early on: "It's like you've had a sense of humour bypass -- everything's so serious, it's like you've got the weight of the world on your shoulders." That really is what it feels like.

6. It gets easier once they're standing on their own four feet

Things begin to relax around the age of two. Twins are often slower to develop than single children -- they're usually about six months behind -- but they catch up by the time they're around five.

My twins have slept in separate bedrooms since they were three months old and they're very independent.

It's difficult at times for people outside the family to see them as separate people, not the same person or one of a set.

So I'm not in favour of dressing twins in the same clothes (I did once and felt guilty about it all day), and I think it's important to create private spaces for them.

They both get one-on-one time with me or my husband once a day, usually at night when I'll read them each a bedtime story.

Delyth Raffell, 40, a writer, is the mother of five-year-old twins Abbey and Ellen Interview by Esther Walker

62pc The increase in twin births since 1980

1 in 60 Non-identical twinning (dizygotic twins) occurs once in every 60 births

1 in 150 Identical twinning (monozygotic twins) occurs in one in every 150 births

22 Number of days, on average, that twins are born prematurely

1 in 5 About 20pc of twins are left-handed; for non-twins the rate is only 10pc

- Esther Walker