Melbourne mum Natasha Corrigan made international headlines earlier this year after giving birth to a 6kg baby - or a "fat little man," as she called him.
Brian Liddle Jr was one of the biggest babies ever born in Australia, and is almost twice the average birthweight.
Corrigan gave birth to Brian after seven hours of a natural labour, which she said extra staff members had to help with due to the baby's size.
Corrigan isn't the first person to give birth to a larger-than-average baby:
* The biggest baby ever was born 10kg in Ohio, according to the Guinness World Records. Sadly, the boy, named "Babe", died 11 hours later.
* Last year, a Perth, Australia, woman gave birth to a 6kg baby through caesarean section.
* Just weeks after, an Indian woman had a 6.8kg baby girl, also via a c-section.
There has been a 15 to 25 per cent increase in babies weighing 3.7kg or more in the past two to three decades in developed countries, according to 2013 report from medical journal The Lancet. Those babies and their mothers face some additional risks.
Though the average US birthweight is 3.48kg and more than 4.5kg is considered fairly large, "what the right size is for any mum or baby is quite a big range," according to Dr Hyagriv Simhan, director of maternal-fetal medicine at Magee-Women's Hospital.
There are certain health conditions, such as diabetes, or gestational diabetes - which develops during pregnancy - that predispose women to having babies over 4.5kg, Simhan said.
A baby that weighs more than 4.5kg poses the risk of delivery complications such as excessive bleeding for the mother, increasing the likelihood of long-term nerve injuries or needing a c-section. Even then, the risk of bleeding and delivery complications loom.
Long-term health complications to the baby include obesity in childhood and potentially beyond, he said.
How some babies get so big
Multiple factors contribute to large birthweight, including diabetes or family history. A woman who is 187cm tall and 80kg is more likely to have a larger baby than a 160cm tall woman who weighs 45kg, Simhan said, adding that physicians attempt to predict birthweight using traditional methods such as ultrasounds and physical exams.
"We have to use these inaccurate methods of gauging size," he said. "In women who are undergoing labour, if we think a baby is larger than average, we'll definitely follow the labour," and potentially suggest a c-section if progress is slow or stalled.
The c-section delivery rate in the US declined for the third year in a row to 32 per cent of births in 2015, the lowest rate since 2007, according to the Centres for Disease Control. More than 2.7 million babies in the US were delivered through vaginal birth in 2015.
Additional risks posed by larger babies
Immediate risks of a large birthweight for the mother are delivery complications such as vaginal and rectal laceration or postpartum hemorrhage, according to Dr Clark Nugent, a professor of gynaecology and obstetrics at the University of Michigan. Long-term risks include high risk of pelvic floor disorders or prolapse, he added.
For the baby, there's also a higher risk of shoulder dystocia, or when the baby's head delivers but the shoulders don't, and oxygen takes too long to deliver.
"Any time that someone is delivering a baby, we have to be prepared for shoulder dystocia," Nugent said.
Other potential health complications include low blood sugar or an elevated blood count, which could lead to the baby being admitted to a neonatal all-intensive nursery.
Recovery time after vaginal deliveries depends on complications, including tears or injuries, which are more common with large babies.
MCT