Why obesity and hormone-disrupting chemicals in plastics may cause girls to start periods sooner

While most ten-year-olds in her peer group were swapping stickers, collecting toys or seeing friends, Milly Watmore spent days each month hunched over in pain due to her period.

While the average age of starting menstruation in the UK is 12, Milly is one of a growing number of girls who start their periods young. She was ten when they started, which created problems, especially at school – and not only due to her painful cramps.

’I couldn’t concentrate all the time in lessons as I was anxious about standing up in case I’d leaked through my clothes,’ says Milly, now 17, from Worcester.

And such experiences are becoming more common. According to research, girls are increasingly starting their periods younger than ever before.

A study published in May found that whereas women born between 1950 and 1969 started their periods at 12-and-a-half years old on average, for those born between 2000 and 2005 the average age was 11.9 years, reported the journal JAMA Network Open.

The Harvard University researchers behind the study found that the proportion of girls starting their periods before the age of 11 had increased from 8.6 per cent to 15.5 per cent.

And while the proportion starting their periods before the age of nine were still tiny (fewer than 2 per cent), they had more than doubled during that same time frame from 0.6 to 1.4 per cent.

They said childhood obesity – “a growing epidemic in the US” – could be a contributing factor, as well as “diet, psychological stress and environmental factors such as endocrine-disrupting chemicals and air pollution”.

While these are US-based figures, experts say the same trend is taking place in the UK – and it’s a trend, they say, that brings a host of problems for girls. According to a new report, 11 per cent of teenage girls in the UK found their periods made them feel as if “life isn’t worth living”.

The survey by Wellbeing of Women, a women’s reproductive health charity, of 3,000 UK girls aged 12 to 18 found that 20 per cent said their period left them ’bed-bound’ and 43 per cent unable to eat or sleep.

Even more concerning, the Harvard study found that earlier onset periods are associated with adverse health outcomes, “such as cardiovascular disease, cancer, spontaneous abortion [i.e. miscarriage] and premature death”.

So why are girls getting their periods earlier?

There are multiple factors involved, says Dr Tania Adib, a consultant gynaecologist at the Lister Hospital in London.

“It’s predominantly down to diet and nutrition – specifically that people are eating more calorific foods and eating more in general, and becoming more overweight as a result,” she says.

Fat tissue produces the hormone oestrogen, high levels of which can trigger the pituitary gland in the brain to produce hormones that stimulate the ovaries to start the menstrual cycle earlier.

“During wartime, when food was scarce, young girls didn’t have as much body fat so periods started later,” says Dr Adib.

But that’s not the whole story – and doesn’t explain cases such as Milly’s, as she isn’t overweight.

Dr Adib says there is research which suggests some hormone-disrupting chemicals in the environment may be involved, such as phthalates or bisphenol-A.

“These chemicals are used in plastic production and are thought to have an oestrogen-like effect,” she says. “They are also found in furniture, children’s toys, fabrics and cosmetics.”

Genetics is another factor, says Dr Shazia Malik, a consultant gynaecologist and UK Medical Director of gynaecological health company DAYE.

“Mothers who started their periods early tend to give birth to girls who start their periods early too,” she says.

“These genetic influences mean the brain signals the release of sex hormones earlier than usual.”

Genetics could have played a part in Milly’s case, as her mother also started her periods aged ten. Even so, Milly was in shock when she saw she had started bleeding while staying with her father (her parents are divorced).

“I saw the blood and panicked,” she says. “I hadn’t learnt much about it at school. I was also at Dad’s house, and he didn’t have any sanitary towels.”

It can be “traumatic” for a girl to start her periods while still in primary school, often before parents or teachers have talked to them about what to expect, says Dr Adib.

“Bleeding for a young girl is quite traumatic, and girls aged nine are not often mentally mature enough for those bodily changes,’ she says.

“I didn’t start mine until I was 14, so I was quite prepared for it. But if I’d started at the age of nine, I think I would have found that upsetting.”

Back at home, Milly’s mum talked her through what to expect and went into school to talk to her teachers. Even so, navigating school while having her period wasn’t easy.

“There were no bins in the girls’ loos, so I had nowhere to put my sanitary towels,” says Milly. “I had to use the teachers’ loo, which was embarrassing at that age.”

Milly’s periods became heavy, and once – aged ten and in year six – she leaked through her school summer dress, not realising until someone told her.

“I had to go and get a spare dress from lost property,’ she recalls. ’It was mortifying, especially as no one else in my year group had started.”

At night, Milly had to sleep on a towel to prevent leaks onto her bedding – but as time passed and her periods got heavier, leaks onto bedding and clothing became more common.

Her GP prescribed tranexamic acid, a medication used to treat heavy bleeding during a period. It works by reducing the breakdown of blood clots, making the flow slower and less heavy.

“I was told the medication would stop me bleeding as heavily, but might make my periods last longer,” says Milly.

Dr Adib says there are other options to help girls with painful periods, such as mefenamic acid, a non-steroidal anti-inflammatory drug.

“As it’s fairly mild, it will take the edge off the pain but won’t necessarily make the periods lighter,” she says.

Really heavy, painful periods that are quite debilitating and difficult to manage in young girls still at school may need to be treated with the contraceptive pill, says Dr Adib.

“But there’s a slight anxiety on the part of GPs in prescribing the pill in young girls,” she says.

“There seems to be a slightly higher incidence of depression and psychological issues in young girls on the contraceptive pill that we don’t see in older women.”

Dr Malik adds: “The pill should not be our first line of defence against period pain or heavy bleeding, as it comes with increased risk of blood clots, weight gain and mood changes.

“There is also an association between adolescents who take the combined pill and lower bone density as adults.

“So it is crucial to discuss these risks with a healthcare provider before starting the Pill or any other medication, especially with very young girls.”

While older women with problem periods might be offered a coil, which provides a form of the hormone progesterone to help thin the lining of the womb, Dr Adib says: “You don’t want to be putting coils in young girls.”

She believes that GPs need to be “made more aware of younger girls starting their periods” and the treatment options for them.

Milly took daily tranexamic acid tablets from the age of 13, when the bleeding was heaviest, and it did become lighter.

“I no longer bled through towels onto my bed,” she says. “The bleed time lengthened to around ten days, but I didn’t mind that.”

The longer periods lasted about six months, then came down to around six days. Still, her period has blighted her life.

“Holidays are a problem,” she says. “If I’m due to start when on holiday, we are able to get a period delay tablet from the pharmacist, which I take to delay my period by a few days.”

She also downloaded an app to help her know when her period is coming, so she can be prepared.

Dr Malik says that for parents, conversations with their children about periods are important.

“Parents should consider preparing their daughters for the changes associated with puberty earlier. Open communication can help girls understand, accept and cope with the changes.

“It’s essential to have these conversations with both boys and girls. It can make a big difference, especially to a young girl, if she isn’t made to feel as if there is something wrong with her. This is, after all, nature at work.”