Way back in 2012, the first episode of Girls showed Lena Dunham’s character Hannah demanding financial support from her parents to help her become a successful writer in New York City. “I don’t want to freak you out, but I think that I may be the voice of my generation – or at least, a voice of a generation,” she informed them, before sliding off her chair in a magic mushroom-induced stupor.

Fast-forward to the final episode of Dunham’s groundbreaking HBO series, which aired on Sunday, and Hannah’s life is looking very different. Now a single mother living in a small town in upstate New York, she’s adjusting to a vision of her thirties that looks very different to what she might have imagined at 23 – although she’s still accompanied by her longtime friend, Marnie (Allison Williams). The episode ends with the screen fading to black after a shot of Hannah staring straight ahead, breastfeeding her new baby.

Hannah’s child, a son named Grover, was the result of a holiday fling with laidback surf instructor Paul-Louis (played by British Star Wars actor Riz Ahmed). In a new interview, Dunham reveals the story behind Hannah’s unusual choice of baby name.

“I came in one day and I was like, ‘The baby's name is Grover.’ And we were like, ‘Sounds about right,’” Dunham tells The Hollywood Reporter.

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She explains that the Girls writing team had been struggling to decide on a name for Hannah’s baby, which – given Hannah’s frequent misjudgements and characteristic pretentiousness – they knew should be “slightly off”.

Grover, Dunham says, “was just odd enough that Hannah would be comfortable with it, while she wasn’t also naming her child ‘Plutonium’.”

The final episode also reveals that it was Paul-Louis, not Hannah, who originally suggested Grover’s name – a narrative twist devised by Girls’ executive producer and writer Jenni Konner.

Read more: The team behind Girls explain the final season’s biggest plot twists

“It was Jenni who had the idea to have Paul-Louis say [that he thought] Grover would be a really nice name for a baby,” says Dunham. “Like, ‘I want there to be some evidence that he is the father and that he mattered.’ So when she put the line in, it felt so beautiful and natural that it all retrofitted so nicely.

Dunham continues: “We knew that the baby's name was Grover Horvath before we knew that ‘Grover’ was the fantasy name of [Hannah's] water-skiing f***-buddy.”

Dunham, 30, also reveals how she thinks Hannah will handle motherhood.

“On the one hand: terrible,” she says. “But on the other hand: aren’t most of us dealing with the fact that we have mums who either weren’t ready to be mums or had some level of resentment about it? … I don’t think she’s going to be any worse than anybody else.”

Dunham adds that while Hannah’s character has often been defined by her narcissism and self-interest, she has also proved that she has the capacity to care for and about others.

“Hannah’s displayed, especially over the last couple of seasons, that other people’s comfort matters to her,” says Dunham. “She doesn’t leave them when it counts. She uses her own strange methods to try to make them feel better.

“She knows how to nurture, even if it’s not always her first instinct.”

Watch: 5 reasons to love Lena Dunham

The decision to end Girls with a shot of Hannah as a mother struggling to breastfeed properly has invariably led to criticism from some viewers, who saw it as a disappointingly traditional ending to a show that sought to portray modern, unconventional womanhood.

“I think it’s quite boring that Girls started out as quite a revolutionary show on young womanhood and ended on the wonders of motherhood,” wrote journalist Marie Le Conte.

“A whole finale about breastfeeding,” another fan wrote on Twitter. “That narrative is tired and boring.”

However, Dunham insists that she and the show’s co-writers were not trying to make a statement about the salving powers of motherhood – nor promote breastfeeding as the best way to care for a child.

“We’re the last f***ing people who have a f***ing opinion on what you should do with your body,” she says. “Anything that makes your day easier, as long as you're not feeding your baby crack in milk, is really good by us.”

Images: HBO