Rebecca surprised the entire family when she announced her pregnancy in The A Word.
Although she's doing her best to support her daughter, Alison is concerned that she doesn't realises how tough it'll be.
The teenager has already dropped out of university to prepare for motherhood.
And in tonight's episode (May 19), it dawns on Rebecca (Molly Wright) that her baby may have autism like her brother Joe.
Does Rebecca's baby have autism in The A Word?
During a heart-to-heart with her mother, Rebecca acknowledges that her unborn child may have autism.
Although she loves her brother Joe to the moon and back, she realises such a diagnosis may mean her life will change more than she realises.
When she originally announced her pregnancy, the teen explained she planned to go back to university to finish her degree.
However, with no partner to help her, going back to uni while looking after a young child with autism will prove challenging.
This thought clearly worries Rebecca.
Heartbreakingly, she's also ridden with guilt for feeling anxious because she adores Joe.
Viewers will not find out if Rebecca's baby has autism this series.
This is because autism is difficult to detect when a child is that young.
According to the National Autistic Society: "Children can be diagnosed as autistic when they’re quite young, in some cases from the age of two.
"But not everyone is diagnosed early in life.
"It’s quite common for a child to not get their diagnosis until they are older, or even an adult, particularly if they don’t have accompanying learning disabilities."
Is autism hereditary?
There is evidence to suggest that some forms of autism are hereditary.
However, scientists and researchers are still unsure which genes could be responsible.
According to the National Autistic Society: "Autism is likely to have multiple genes responsible rather than a single gene.
"The difficulty of establishing gene involvement is compounded by the interaction of genes and by their interaction with environmental factors.
"For these reasons genetic testing to diagnose a pre-disposition to an autistic spectrum disorder is not, at present, possible."
What happens in The A Word tonight?
It's a big day for Joe this evening (May 26).
Alison (Morven Christie) organises a sponsored walk for for his classmates to raise money for the school.
Planning the event brings gives her a chance to bond with Joe's teacher Heather (Julie Hesmondhalgh).
During a heart-to-heart, the pair begin to open up one another and their conversation leaves Alison contemplating a new career.
When the big day arrives, the pressure off being centre of attention proves too much for Joe (Max Vento) and he refuses to leave his room.
However, Rebecca (Molly Wright) turns up and the mother-to-be saves the day – but there's clearly something on her mind.
Later on she finally comes clean to Alison about what's been worrying her.
Elsewhere, Paul (Lee Ingleby) is forced into a situation where he has to spend time with Ben (David Gyasi)..
Alison then finds out she isn't the only one that's moved on from her marriage.
The A Word series three is on BBC One, Tuesdays at 9pm.
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