But what if the child also happens to be a newborn? And the "sickness" is diagnosed as cancer?

Poppy Grace Middleton's parents were told she had acute lymphoblastic leukaemia when she was just 11 weeks old. It's a cancer of the bone marrow and blood where the bone marrow makes too many lymphocytes (a type of white blood cell).

She underwent surgery at 12 weeks of age and has been in and out of John Hunter Hospital ever since.

Poppy is now six months old and cute as a button. Bright blue eyes, chubby cheeks and a cheeky smile. She's loved, and she knows it, but she's blissfully unaware of what is happening to her and around her.

For her parents Carly and Tresne Middleton, though, it's a different story. They are living and breathing the diagnosis, the treatment, the hospital stays, the fear of the unknown, every second of every day.

And as they're living it they are busy making sure Poppy is happy and well-adjusted - and raising awareness of the importance of blood and bone marrow donations.

Carly and Tresne - who were contestants on My Kitchen Rules in 2014 - have been remarkably open about theirs and Poppy's journey. They say a doctor encouraged them to "capture moments to share with her when she is older so she can see how strong, resilient and brave she is".

They generously gave up their time to answer some questions, together, for Weekender. Here is their story.

"We had taken her to the private hospital [Lake Macquarie] as it was after GP hours and she was vomiting larger volumes than we thought was normal for a baby.

"As she is our only bub we were unsure if we were being over cautious but we are so grateful we took her to get checked out.

"Interestingly, at Poppy's six-week check-up a nurse noticed a bruise on her leg and suggested we have an ultrasound on it. The ultrasound results showed that it was simply a bruise, but it stuck around for five weeks without improving.

"Little did we know at the time that bruising is one of the most common symptoms associated with blood cancer."

Poppy was diagnosed with acute lymphoblastic leukaemia.

"The drive between the private hospital and John Hunter is a blur, neither of us can really remember it," Carly says.

"We were transferred into the Paediatric Intensive Care Unit (PICU) and Tresne kept fainting. I could not stop bawling my eyes out, I felt I might die from a broken heart.

"We have both endured a great deal of trauma in our lives but this felt completely unbearable.

"Poppy had surgery that night under a general anaesthesia to insert a temporary central line, which is a short-term catheter placed in the vein located in her neck.

"Tresne and I had waited so long for our little baby. We started trying for a bub back in 2012, and here we were nine years later watching our baby go into surgery.

"It just seemed incomprehensible."

On the day of Poppy's surgery, Carly and Tresne notified their followers on Facebook and Instagram of Poppy's diagnosis with this additional message: "Poppy's treatment is going to be a long hard road and she will need a lot of blood. If you would like to help, we ask if you can donate blood. Blood stores are critically low because everyone assumes the blood donation centres are closed due to COVID."

The love and support they received - from friends and strangers - stunned them.

An account in Poppy's name was set up with the Australian Red Cross and within a week 111 blood donations had already been made.

"The blood, plasma and platelet donations are vital for conditions like Poppy's," Carly and Tresne explain.

"The amount of blood that we've personally seen used daily in ward J1 is mind boggling, and that's just one ward. It's because chemotherapy affects the patient's blood counts.

"So, for example, chemotherapy could lower Poppy's haemoglobin levels. A normal range of haemoglobin is 95 to 100 and typically they will give Poppy a blood transfusion of packed red blood cells if her haemoglobin falls below 70, which it does regularly.

"When Poppy's haemoglobin drops, she becomes very tired, her heart rate rises, and she becomes very pale. Poppy's platelets also drop as a result of chemotherapy and low platelets mean a higher risk of bleeding. She has had numerous platelet transfusions. Normal platelet counts are 150 to 400 and Poppy has had a platelet count as low as eight."

Poppy has also had albumin transfusions to assist with fluids and to improve renal function by expanding total blood volume, and intravenous immunoglobulin because the chemotherapy has impacted her ability to make antibodies that fight infections. Both are blood products manufactured from human plasma.

Typically, she requires a prescription of fresh blood no older than seven days because she is so young.

To date, little Poppy has endured three protocols for her leukaemia treatment. That's tough on anyone, let alone a baby, and unfortunately she became very sick and needed oxygen support.

"She had high blood pressure and was tachycardic (high heart rate) many times," Carly and Tresne explain.

"Poppy was also vomiting periodically during this time and had to be put on feeds down the nasal gastric tubes when she couldn't breastfeed as her mouth was ulcerated. She developed stridor (seesaw sounding) breathing and needed an ear nose and throat procedure to fill a laryngeal cleft to alleviate her choking.

"In between this protocol and the next Poppy's throat and oesophagus became so inflamed that she could no longer have the nasogastric (NG) feeds and so she had to go on TPN (total parenteral nutrition), a form of nutrition that goes directly into her veins through her central line. At this time Poppy received Dexamethasone (another steroid) and it made her very hungry and very cranky. The nurses call it 'baby roid rage' and Poppy's sleep was negatively affected."

More chemotherapy was administered through her central line. Again, Poppy became very ill.

"She was admitted to PICU (Paediatric Intensive Care Unit) after experiencing a series of septic showers that caused her extreme pain and she was vomiting up bile. It is likely there was a germ in her central line, so she was given four different antibiotics to fight it. It was very frightening, especially seeing as my mother passed away due to sepsis in 2019," Carly says.

"What is next for her really depends on the next bone marrow aspirate, which is where the oncologist takes a sample of her bone marrow to check how much leukaemia is left. This may mean further chemotherapy, or other types of antibody therapies which attack the leukaemia. We are hoping to have a bone marrow donor and undergo the bone marrow transplant early next year."

If the transplant goes ahead, it will likely be done at a Sydney hospital and Carly and Tresne will require the services of Ronald McDonald House. They raised money for the children's charity in 2014 through McHappy Day, never dreaming at the time they would one day have cause to use it themselves.

Peppered throughout Carly and Tresne's detailed medical updates online are happy stories. Giggles from a cheeky Poppy. Milestones reached. Take, for example, this post on September 26: "Poppy is attempting to roll! This is so exciting and surprising for us because she has lost a lot of head and neck control due to the amount of time she has spent lying in bed. Go Poppy, you amazing super-healer!".

And this, posted on October 10: "This week an email was received from Lifeblood with some exciting news ... 'A special mention to new Lifeblood team Poppy Grace who in September had 34 new donors and also the 3rd most donations in total for September'. You guys are responsible for the national total of 417 lives saved now!! But it is so rewarding being home! We're having the best time going through all of Poppy's thoughtful gifts from friends and family. She's really beginning to show an interest in her toys and she loves being read to which is so exciting to see. She really is a warrior, and we are so so privileged to be her Mums."

As of November 27, 624 lives have been saved under Poppy's name.

"The way it works is people book in to donate blood and when they donate, they simply tell the staff member that they'd like their donation to be logged in Poppy Grace's Lifeblood group," Carly and Tresne explain.

"Each blood donation can save up to three lives. The donated blood goes where it is needed most and those who donate get a text message soon after to tell them where the blood went.

"In Australia, we need more than 29,000 donations every week to meet demand. This blood is saving lives daily. There is no substitute. In cancer patients it is very common to need a lot of blood, frequently, during chemotherapy. It is such a beautiful gift to give. People can help by booking an appointment and becoming a regular donor at lifeblood.com.au/blood."

They also encourage people to consider donating bone marrow, saying bone marrow donations are so low in Australia that generally the donors come from overseas.

Carly and Tresne believe they are doing what any parent would do - I beg to differ - and they are full of praise for the medical staff caring for their daughter.

"Poppy has spent more than her fair share of time in PICU and J1 (Children's Oncology Ward). The doctors and nurses have become like family. We would especially be lost without the nurses in J1, where we have spent the majority of Poppy's life. They genuinely care about each and every patient and they are always willing to take time to explain things to you, listen to your concerns with empathy, and respond kindly. They are an above and beyond group of outstanding humans who are worth their weight in gold.

"As for us, we are putting all our energy, thoughts and prayers towards Poppy's eventual cure. We are praying that Poppy will live a long, happy, healthy life, free from leukaemia.

"It is amazing to feel the love from people who care about our beautiful girl. She is an extraordinary baby with the happiest disposition, and she has brought so much joy to so many lives. We are so appreciative of the people who have taken time to reach out and help us feel supported. We are also eternally grateful to those who have helped us financially by donating to Poppy Grace's GoFundMe to help with this unexpected and harrowing period of our lives."

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