Ms Rita Lim was 20 when she first got pregnant in 2007 - and then lost her unborn child 10 weeks into her pregnancy.

This happened again twice, in 2010 and 2013.

All three miscarriages were attributed to lupus, an incurable condition that Ms Lim was diagnosed with when she was 17 years old.

"I felt very sad, like it was not meant to be," she said. "I wanted to give up after the third miscarriage because the heparin (blood thinner) injections were so painful, but I love kids and I've always wanted to have kids."

Ms Lim, who is now 30, had to switch from the oral medication of warfarin, a blood thinner, to the injection form of heparin during pregnancy because the former can cause birth defects.

Lupus, an autoimmune disease, happens when the body's immune system becomes dysfunctional and attacks its own tissues and organs.

Instead of destroying only bacteria and viruses in the body, the immune system also targets tissues and organs, confusing them for "foreign invaders", said Dr Aisha Lateef, who is Ms Lim's doctor and head of the division of rheumatology at National University Hospital (NUH).

The disease was recently in the spotlight when American pop star Selena Gomez said last month that she underwent a kidney transplant due to lupus.

The disease may manifest in different ways for different people.

Systemic lupus erythematosus (SLE) accounts for the majority of lupus cases.

Adjunct Assistant Professor Madelynn Chan, a senior consultant at the department of rheumatology, allergy and immunology at Tan Tock Seng Hospital (TTSH), noted that the disease can hit vital organs.

"In about half of these cases, a major organ or tissue in the body, such as the heart, lungs, kidneys or brain will be affected," she added.

The joints, skin, blood cells, lungs and intestines may also be damaged, said Dr Lateef.

Common symptoms are extreme fatigue, fever, painful joints, hair loss and a butterfly-shaped rash over the nose and cheeks.

The effects of lupus can be more marked in pregnant women.

In general, they face a higher risk of flares, foetal loss, pre-term birth, intra-uterine growth restriction and neonatal lupus, said Dr Lateef.

During Ms Lim's pregnancy in 2015, for instance, she suffered from flares - episodes when the symptoms of lupus worsen - and intermittent bleeding. She was also hospitalised twice for urinary tract infection and diarrhoea.

The pregnancy was deemed "very high risk", said Ms Lim, because of the severity of the disease and previous blood clots in her brain, which puts her at risk of a stroke. Any clots that form in her lungs would lead to breathing difficulties as well.

But with the support of her husband, 40, who helps her with her laundry business, as well as her family, she managed to get through the trying pregnancy and gave birth to her son, Anderz, in 2015. Tests show that he does not have lupus.

"I'm very fortunate to have a lot of support from my family members," said Ms Lim. "Lupus has taught me to let things go more easily; if not, I wouldn't be able to survive this."

MAINLY WOMEN AFFECTED

Lupus is uncommon, affecting only about 0.1 per cent of the population. TTSH sees more than 1,500 patients with SLE each year, while Singapore General Hospital (SGH) has 800 lupus patients a year and NUH, about 600.

Young women are mostly the ones who are afflicted, said Dr Poh Yih Jia, a consultant at SGH's department of rheumatology and immunology.

In particular, lupus occurs nine times more often in women of childbearing age - between 15 and 45 years old - compared with men, said Dr Poh.

Prof Chan noted that the female hormone oestrogen may have a role. "It is thought to be related to the influence of oestrogen on the immune system, as well as hormonal changes during puberty and the childbearing years," she said.

And not only are Chinese, Malay and Indians more prone to developing lupus than Caucasians, the disease affects more of their major organs as well, added Prof Chan.

But the exact cause of lupus remains unclear. What is observed is that people who have family members with lupus are also at a higher risk of developing the disease.

About 8 per cent of lupus patients have at least one close family member, such as a parent or siblings, with the disease, said Dr Poh.

For allied educator Ang Yeh Ray, 37, lupus runs in the family.

She was diagnosed at 12, and her mother, aunt and grandmother - all on her mother's side - had lupus.

Her aunt died at the age of 28 when her body weakened after she stopped taking her medication for lupus. Her late aunt was unhappy that the medicine made her look bloated, she added.

Ms Ang, however, has come to accept her bloated appearance. Other problems include anaemia, fatigue, hair loss and swollen legs due to water retention.

"Every time there's a flare, it's like a reset button," she said.

"But I've come to accept it and not to be too stressed and think negative thoughts, which makes the lupus more active."

Indeed, some environmental factors can trigger the onset of lupus. These include extreme exposure to sunlight, certain medications, infections, exhaustion, emotional stress and physical stress due to events like surgery, injury, pregnancy or puberty, said Prof Chan.

She noted that about 5 per cent of children born to mothers with lupus will develop the disease, though this cannot be predicted.

"The pattern of inheritance does not follow a simple pattern," said Dr Poh. "Even in patients with a family history of lupus, the clinical presentations may be different."

LIFELONG TREATMENT NEEDED

The treatment for lupus varies from patient to patient.

They are often prescribed hydroxychloroquine, which can prevent flares, stabilise the disease and prevent organ damage.

Another common drug is the steroid prednisolone, which controls inflammation in the body.

"A large majority can lead almost normal healthy lives as long as they continue treatment, which can also vary with time and between patients," said Dr Lateef.

The survival rate of patients with lupus has improved significantly.

In 1955, less than half live for another five years after diagnosis. Today, more than 85 per cent survive at least 10 years, according to recent studies, said Dr Lateef.

However, there remains "an urgent need to uncover newer and more effective treatment with fewer side effects", said Dr Poh.

Current treatments like immunosuppressive agents, for instance, dampen the immune system and this makes the person more vulnerable to infections.

While lupus is not influenced by specific foods, patients will fare better if they keep fit and healthy.

They should also refrain from smoking and avoid getting stressed, advised Prof Chan.