A woman has given birth to a baby weighing 11lb 8oz, which is roughly the average size of a two or three-month-old.

When Sarah Dines, 35, from Broadstone, Dorset, welcomed her first baby, Montague, now 11 months, he went straight into toddler clothes, and now wears items for two to three-year-olds.

Initially the teacher had hoped to have a home water birth without pain relief, but instead had to deliver Montague via C-section, partly due to the newborn’s size.

“He was so big when he was born, he looked ridiculous,” Dines explains.

“When the doctors took him out, they were all laughing and I didn’t know why at first.

“One of them said he was ready for school, and the little towel they wrapped him just didn’t fit.”

Dines says baby Montague was on the 99.9th centile for his height and 99.6th for his weight, putting him up there with some of the biggest UK newborns.

Watch: Ten-month-old baby mistaken for toddler as he weighs a hefty 29 pounds

Interestingly none of the doctors could account for Monty’s unusually large size.

“After he was I was tested for gestational diabetes, but it was never positive,” she says.

“I’m 5ft 9in, and my husband Elliott, 41, is 6ft, so we were never going to have a small baby.

“Neither of us were particularly big when we born, I think I just carry big babies.”

Though Dines believed her pregnancy bum was on the large side, doctors predicted Monty would weigh around 8lb.

“All the scans were normal, so I was all set to go to have a home birth,” she explains.

“Initially, I wanted to have a water birth and that was going to be my own form of pain relief.

“But Monty was 10 days late, so it got to the point where the doctor was talking about a planned C-Section or inducing me.”

In the end Monty was delivered via an emergency C-section.

“My water broke in the morning, and I was in full labour that evening, but I hadn’t dilated at all,” Dines explains.

“The pain got so bad that I asked for gas and air, and then eventually we had to go into hospital.

“I didn’t want to be induced, and we had spoke about a planned caesarean because he was so late, we even did all the paperwork.

“That ended up being useful because we had to go in for the emergency C-section, so we’d already filled in all the forms.”

While the mum-to-be had taken plenty of clothes into the hospital with her, none of them actually fit the newborn after his birth.

“Even the little cap they gave him at the hospital was too small,” she says.

“My sister had to run and buy me some nappies because none of the ones we had fit him either.

“As he’s got older he’s gone up and up in sizes, he’s always been in bigger clothes than his age.

“He’s a week off being one and he’s in stuff for a 2-3 year old.”

According to data from the World Health Organisation (WHO), the average weight of a baby at birth, both boys and girls, is 7lb 8oz.

Meanwhile, the average weight of a two-month-old baby boy (on the 50th centile) is 11lb 5oz and a baby girl is 10lb 5oz, while a three-month-old baby boy is 13lb 2oz and a girl is 12lbs.