When Sarah (not her real name) was six years old, she was taller than her peers and had larger than normal breasts.
Her mother simply pinned this down to genetics and body fat. "We didn't realise these were signs of early puberty. We thought she was just growing up too quickly," said Mrs Lim (not her real name).
Sarah was diagnosed with early, or precocious, puberty during a Health Promotion Board check-up when she entered primary school.
When she was referred to a paediatrician in hospital for further check-ups, Mrs Lim was surprised and read up on early puberty after the consultations. She said it was a condition that was rarely discussed, much less known.
Paediatricians said they are seeing more children like Sarah who are reaching puberty early, most likely because parents are becoming aware of it.
Early puberty is when a child's body begins changing into that of an adult too soon. It results in rapid growth, changes in body shape and size, and the development of the ability to reproduce.
At the National University Hospital (NUH), where Sarah is a patient, the number of children who have the condition has risen from seven in 2009 to 22 last year.
"Puberty is like a volcano which hasn't erupted. It is normally under inhibition, until the child reaches a certain age when the inhibition forces are lifted," said Dr Cindy Ho, a consultant at NUH's division of paediatric endocrinology.
Puberty is like a volcano which hasn't erupted. It is normally under inhibition, until the child reaches a certain age when the inhibition forces are lifted.
DR CINDY HO, consultant at the National University Hospital's division of paediatric endocrinology.
"SWITCH" TURNED ON EARLIER
Early puberty begins before the age of eight in girls and nine in boys.
The two main causes are central precocious puberty and peripheral precocious puberty, said Dr Ho.
Symptoms of precocious puberty
Early puberty begins in girls who are younger than eight years old and in boys below nine.
These are some signs:
GIRLS BELOW EIGHT
•Pubic hair growth
•Vaginal bleeding and menstruation
•Adult body odour
• Excessive height gain during the child's pre-primary school years
BOYS BELOW NINE
•Enlarged testicles and penis
•Pubic hair growth
•Body odour of an adult
•Deepening of the voice
•Excessive height gain during the child's pre-primary school years
Much more common is central precocious puberty, or "normal early puberty".
She said: "In central precocious puberty, the whole sequence kicks in because the switch for puberty in the brain gets switched on earlier."
There is usually no identifiable cause for this type of precocious puberty.
Peripheral precocious puberty, on the other hand, is the result of elevated sex hormones - oestrogen in females and testoterone in males - in the child's body that were not activated by the brain's puberty control centre.
It could hint at underlying problems in the body, said Dr Ho. Peripheral precocious puberty could be due to tumours in the testes or ovaries which are secreting the excess hormones. It could also be due to genetic disorders involving abnormal hormone production by the adrenal glands.
Dr Christelle Tan, a paediatric medicine specialist and consultant at Raffles Specialists' Holland Village centre, said: "Children with early puberty should see a paediatrician to determine if the puberty is a normal or variant type."
Early puberty can also be caused by exposure to external sources of sex hormones, such as hormone replacement patches used by the child's family members.
Children who are significantly overweight tend to start puberty earlier, said Dr Ho.
Most of her patients with early puberty are six or seven years old, with a handful below the age of five.
Doctors said there is little parents can do when early puberty occurs.
However, Dr Ho said children should lead a healthy lifestyle to reduce the risk of obesity and early puberty.
Dr Alison Snodgrass, a consultant at KK Women's and Children's Hospital's (KKH) department of paediatrics under its general paediatrics and adolescent medicine service, said good nutrition and adequate sleep are important for the normal progression of growth and puberty.
She said: "Early puberty occurs more commonly in girls. It is usually physiological (consistent with the body's normal functioning).
"There may be a family history of early puberty. Girls who are obese also tend to go into puberty earlier."
Signs of early puberty in girls include breast development, pubic hair growth and vaginal bleeding.
Boys in early puberty might experience pubic hair growth, enlarged testicles and penis, acne and a deeper voice, among other signs.
IMPACT ON CHILD
Besides underlying problems, early puberty can also have physical and social repercussions for a child.
The child may end up growing into a short adult, for example. Although children with early puberty might experience early growth spurts, their bones mature more quickly than normal.
As a result, they often stop growing earlier than usual and may be shorter than average when they become adults, said Dr Ho.
Children with early puberty may be extremely self-conscious about the changes occurring in their bodies. And they may not be mature enough to handle the emotional and physical changes which come with puberty, she added.
"Children may not know how to handle mood swings and take care of their personal hygiene. These things might be scary to them."
The changes in the child's body may also make her vulnerable to sexual abuse.
Treatment, depending on the cause of the condition and how early the onset is, might be necessary to limit these effects.
Injections containing hormones to block the puberty are usually administered, said Dr Ho. These injections are usually done once a month or every three months.
A monthly injection costs more than $200, depending on the level of subsidy. The injections stop once the patient reaches the normal age of physical maturity.
Parents do not need to be overly concerned but, at the same time, they should not ignore the signs of early puberty, said Dr Tan.
"Parents are becoming more aware of early puberty and this is seen in the increase in the number of patients over the years," she said.
Although there is little that parents can do to prevent early puberty, they should seek treatment for their child.