The subject is close to her heart: all four of her foster children were exposed to harmful substances in the womb.

She wants doctors, nurses, family members and carers, as well as teachers and employers, to understand the dangers.

Her main message? Complications from exposure to substances during pregnancy – whether legal drugs such as prescription medicines, alcohol and nicotine from tobacco, or illicit ones – do not always end once an infant withdraws from them after being born. They can be lifelong. And serious.

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For example, nerve cell development and function can be damaged, Blythe says, which can manifest as behavioural problems, from poor impulse control to attention issues.

To spread the word, Blythe – along with Australia-based neonatologist Dr Ju-Lee Oei – will share their insights in a webinar on September 20, titled “Prenatal Substance Exposure, Neonatal Abstinence Syndrome (NAS), and their Implications”, organised by Hong Kong non-profit organisations Adoptive Families of Hong Kong (AFHK) and Mother’s Choice.

“One common thing we see with children exposed to harmful substances during pregnancy is compromised executive function,” Blythe says, referring to the set of cognitive skills that control a person’s abilities and behaviours.

“They might not be able to follow more than one instruction at a time or control their impulses.”

Short-term working memory and mental flexibility – “the ability to adapt to change” – can also be impaired. Many children, Blythe says, are misdiagnosed as being on the autism spectrum.

“A child might feel insecure if there’s been a major change in their routine, such as a casual teacher assigned to a classroom because the usual teacher is away sick,” she says.

Behavioural problems often result, and the child may be reprimanded by teachers who are not aware of their “invisible” neurological condition. “That’s why I do a lot of workshops in schools.”

Erica Liu Wollin – a Hong Kong-based clinical psychologist who is mediating the webinar – says prenatal exposure to alcohol is a concern.

“People think if it’s legal, it’s safe,” says Wollin, who helps adoptive and foster families with children who had difficult starts in life, including those with fetal alcohol spectrum disorders (FASD), a group of conditions that can occur in those exposed to alcohol in the womb.

While the minimum amount of alcohol which can cause FASD in an unborn child is not known, a growing body of research has found that even low-level drinking can harm the developing fetus.

But the message – “no amount of alcohol is safe for a developing fetus” – is a difficult one to deliver in a city like Hong Kong, says Wollin, where alcohol is tolerated and ingrained in the social and corporate fabric.

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“Preventing chances of alcohol exposure during pregnancy relies on accurate medical and public health guidance, treatment of addictions and mental health issues, social support, and use of contraception if you are using substances,” says Wollin.

More awareness is needed, she says, adding that FASD is an issue that commonly affects adoptive and foster families. “Despite this, few families are informed or prepared to recognise or handle the unique challenges that come with it.”

For babies exposed to harmful substances in the womb, the challenges can manifest in different ways – and at different stages of life, says Blythe.

“They’re going through such significant withdrawal,” she says. “They get the shakes and it’s obviously a traumatic experience.”

These babies, she says, seem perfect. “But the problem is they’re so sleepy and not looking for attention so parents, especially new or inexperienced ones, aren’t going to pick them up, so there’s a lack of socialising and bonding.” There’s also a higher chance they will develop learning disabilities later in life.

Blythe sees many foster children and carers trapped in a cycle of trauma. Parents not informed about potential behavioural issues associated with prenatal substance exposure are not equipped to care for them. Babies who are not properly diagnosed don’t receive proper treatment.

Training, transparency – “and more research funding” – is needed to break the cycle.

“There’s also usually a period spent in hospital, which sees an infant without an attachment figure, so that’s another trauma that can stunt neurologic growth because they’re not being stimulated.

“Then we traumatise children again by giving them to loving people who don’t understand the trauma they’ve experienced and things go wrong because they react.”

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Environmental factors often linked to drug use during pregnancy – poverty, poor nutrition, stress – can also hinder a child’s development.

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“Substance abuse in Hong Kong has been a problem for a long time, but there’s very little awareness about the risks during pregnancy. That has to change,” says Garnaut.

“There is not a consistent message from the medical community about alcohol use during pregnancy,” she adds.

“I’ve had many people say to me that their doctor says it’s OK to have a little amount of alcohol during pregnancy … Adoptive parents are told ‘you’re going to love this child’ and ‘everything’s going to be fantastic’, but it’s much more complicated.”