Why Britain's babies are getting BIGGER

As Zara gives birth to a 9lb 3oz whopper (ouch!), the intriguing reasons ...

WHEN Zara Tindall gave birth to her second daughter last week there was a collective cry of joy from the nation. Coming just 18 months after Princess Anne’s daughter suffered a miscarriage, few could fail to be moved by the news that the adorable Mia Tindall was now a big sister.

But for many women that first ‘aah’ was followed by an eye-watering ‘ooh’, — because Lena Elizabeth, the new offspring of Zara and her ex-rugby-playing husband Mike Tindall, tipped the scales at a whopping 9lb 3oz. But it’s not just the Tindalls.

Across the country babies are getting bigger and bigger — and it’s not always big women having these big babies. A 10lb baby, once something of an oddity, is now not unusual.

In the post-war years, as diets and health care have improved, there has been a steady upward trend in birth weight, pushing the current average birth weight to 7lb 8oz for boys and 7lb 4oz for girls — up 2oz and 1½oz respectively since 1970. The average takes in the fact that more premature babies survive nowadays, too.

And at the other end of the scale, the number of 10lb babies has soared. Between 1993 and 2003, the number of babies born tipping the scales at above 9lb 15oz increased by 20 per cent.

There were 9,200 of these ‘whoppers’ born in 2015 — and 851 weighing 11lb or more.

But is it always a good thing? Is a big baby always a bouncing one? Read on . . .

HOW BIG IS TOO BIG?

WHILE there is no set figure for how much a newborn should weigh, the Royal College of Midwives uses 8lb 13oz as its guideline for the tipping point between a healthy weight and a potentially problematic one. The technical term is a ‘macrosmia’ baby, meaning ‘large body’.

In the majority of cases, oversize babies are born to mothers who are diabetic, when excess glucose in the mother’s bloodstream is transferred to the baby during pregnancy, causing it to secrete increased amounts of insulin, resulting in increased tissue and fat deposits. But, as Zara has shown, there are plenty of healthy, average- sized women unexpectedly producing big babies, too.

‘Babies, like the rest of us, are getting taller and heavier because we have better nutrition and quality of life,’ says Shazia Malik, consultant obstetrician and gynaecologist at Barnet General Hospital and the Portland Hospital in London.

‘There is also a question mark over what effect hormones in food and water are having on the size of babies and adults, but that is still to be determined.’

IS IT DANGEROUS FOR MOTHER AND CHILD?

WHILE the thought of anyone giving birth to a 10lb baby is enough to make your eyes water, is it actually risky for women having infants this size?

It is no coincidence that the caesarean rate has risen in line with birth weights: there were 73,551 elective caesareans on the NHS in 2015-16, which was about 6,750 more than in 2011-12. Lawrence Mascarenhas, consultant obstetrician and gynaecologist at Guy’s and St Thomas’ Hospital, says that while women should be allowed to choose to give birth to big babies naturally (we don’t know not), whether the labour Zara opted should to be or monitored very carefully and is not without risk. ‘When the cervix dilates, the baby’s head engages and goes into the mid or lower pelvis and can get stuck,’ he explains. ‘Forceps or a ventouse (a suction cup that attaches to the baby’s skull, to enable it to be pulled free) may be required which increases the chance of the mother tearing or having a postpartum haemorrhage.

‘More rare is the case where the baby’s head is delivered but the shoulder gets stuck — this is known as shoulder dystocia — and in extreme cases could lead to the baby’s shoulder being fractured and the baby being starved of oxygen and suffering brain damage.’

For women known to be carrying babies over 8lb 12oz, Mr Mascarenhas normally suggests an induction at 39 weeks or a planned caesarean.

Midwife and Professional Policy Adviser at the Royal College of Midwives Janet Fyle says women shouldn’t rule out a natural birth, however.

‘ Babies, especially big ones, have to do an awful lot of work to get their head into the right position of the pelvis for delivery, and there might need to be the use of forceps, ventouse or an episiotomy (a cut). But a smaller woman can give birth vaginally and frequently does. We don’t want to frighten women into thinking they can’t do it.’

WHY SIZE CAN STILL TAKE US BY SURPRISE

GETTING a handle on the size of the baby during pregnancy is crucial, yet some still manage to slip under the radar and surprise everyone. This is because the measuring process is far from an exact science and even very experienced doctors and midwives can ‘miss’ a big baby.

A big bump does not necessarily mean a big baby — as shown by U.S. actress Eva Longoria recently, whose enormous belly produced a little 6lb 13lb baby boy. A bump’s size and shape is determined by many factors including amniotic fluid and the mother’s abdominal muscle tone.

‘After 28 weeks, we measure the fundal height — the distance from the pubic bone to the top of the uterus — in centimetres, which should be equivalent to the number of weeks, so 20cm at 20 weeks and so on,’ says Mr Mascarenhas.

‘If it deviates by more than 2cm for the number of weeks then we say it is large for its date and we recommend an ultrasound scan to take a closer look at the baby’s size. If the baby’s abdominal circumference is above the 90th centile in the scan then we presume it will be over 4kg (8lb 12oz) and can advise accordingly.

‘But unfortunately, the fundal height measure is quite crude and can be inaccurate and in 50 per cent of cases the baby could be large and we wouldn’t necessarily know.’

DOES A BIG BABY ALWAYS GUARANTEE A HEALTHY BABY?

INTERESTINGlY, there is still conflicting research as to whether bigger babies face more health problems later in life — or in fact may be at an advantage.

One Cambridge university study from 2014 found that heavier newborns may be better protected from diseases in later life than those with a low birth weight, while other older studies found bigger babies fared better academically.

Other studies have suggested big babies are more at risk of type 2 diabetes as adults, however.

lawrence Mascarenhas says there can be further complications for the mother after having a large baby that are much less talked about — such as urinary incontinence and problems with their sex lives, which can require surgery to repair.

The babies themselves may need extra monitoring beyond the labour ward as big babies have big appetites and new mums need to adapt — quickly.

This is sometimes more difficult than others.

‘In the 24 hours after the birth we keep the babies in hospital to make sure they’re feeding well, maintaining their blood sugar and keeping warm because bigger babies have a larger surface area over which they need to distribute their blood sugar,’ says Janet Fyle.

And for new mums, this could mean less sleep — and exhaustion is a well-known trigger for depression, as well as concerns over whether the baby is receiving an adequate quantity of calories.

WILL THEY GROW UP TO BE HUGE?

A BABY’S size at birth is determined not by the parents’ genes but by conditions in the womb. Big babies are ones who have received the optimum mix of nutrients and oxygen throughout.

The longer the pregnancy, the more growing and fatlayering time there is, too. Women who go a week or two over due date tend to have heavier babies (babies can put on about 8oz a week in the last four weeks of pregnancy).

Once they’re out of the womb however, the genes take over. Most babies simply ‘taper off ’ and grow to be average- sized children and adults like their parents.

Tall people are likely to have a bigger baby — their genes will determine a longer skeleton — but not one that is abnormally big.