When she was 38, Victoria Mapplebeck found herself single, pregnant and broke. She had to quit her job as a TV director because the long hours were impossible for a lone parent, but she missed filming. So she turned the camera on her own life instead, and began filming her son Jim as he grew up.

“I first began documenting our lives with my old DVCAM before shooting almost daily on five generations of smartphones,” Mapplebeck said. “I recorded hundreds of hours of footage over the course of 20 years, including each twist and turn in Jim’s life, from the thumbs up he gave me during my first scan, to his first day at college.”

With the blessing of her son, now 20, Mapplebeck has turned that footage into a film, Motherboard, which is showing at the London film festival (LFF). It is an unfiltered testament to life in all its beauty and pain – from Jim growing into an articulate and funny individual, to her battle with breast cancer and the challenges of the Covid pandemic.

“My aim was to build a complex, personal and unsentimental portrait of a mother-son relationship from birth to adulthood,” the Bafta-winning director said. “I wanted to create an antidote to the judgmental and unrealistic expectations we have about motherhood, creating an honest, funny and relatable film for any mother who has wept tears of both joy and frustration.”

Motherboard is just one of many films showing at LFF this year that explore the themes of mothering and maternal challenges. Other titles include Ben Taylor’s Joy, which tells the remarkable true story behind the birth of Louise Joy Brown in 1978, the world’s first “test-tube baby”.

The Netflix film, which is having its world premiere at the festival, is told from the perspective of Jean Purdy (Thomasin McKenzie), a young nurse and embryologist who joined forces with the scientist Robert Edwards (James Norton) and surgeon Patrick Steptoe (Bill Nighy) to “unlock the puzzle of infertility by pioneering in vitro fertilisation”.

Also in the line-up are Nightbitch, Marielle Heller’s genre-bending adaptation of Rachel Yoder’s 2021 novel, which stars Amy Adams as a mother who puts her career on hold to parent her toddler; and the Witches, Elizabeth Sankey’s powerful personal essay weaving women’s experience of postpartum depression with mosaic clips showing how witches have been portrayed throughout the history of film.

Sankey has previously written for the Guardian about her experience on a psychiatric ward that treats women with perinatal mental health issues. “I was in a horror film … and the worst part? The person I was in danger from was me,” she wrote.

There is also Darren Thornton’s comedy drama Four Mothers, which tells the story of a queer Irish novelist juggling four very different mothers.

“From a robot bringing up a baby gosling (Wild Robot) to a woman embracing her animal instincts (Nightbitch), extraordinary mothers abound in this year’s programme,” said the festival director, Kristy Matheson.

“After a few years of great father-daughter films, this year mothers/sons are taking centre stage once more! In the charming and funny Four Mothers an octogenarian mum keeps her successful literary son on his toes, while the unshakeable familial bond sits at the heart of our opening night film Blitz. Across our many months of viewing, the team encountered so many different sides of motherhood – full of hope, resilience and invention.”

Mapplebeck said it was “great to see” the number of films at LFF this year exploring motherhood. “Their popularity proves that there is a huge audience for raw and intimate stories about motherhood, whatever your family looks like,” she said.

“We were once turned down by a producer who told us that Motherboard felt too ‘small’ for him. He wanted ‘big stories about true crime and space, epic journeys’. But raising my son alone, him meeting his dad for the first time, the two of us surviving my breast cancer diagnosis, that’s a pretty epic journey.”

LFF opens on Wednesday with the premiere of Steve McQueen’s Blitz, which follows the travails of a young boy separated from his mother during the second world war and stars Kathy Burke, Saoirse Ronan and Paul Weller.

Other highlights include the closing film, Morgan Neville’s Lego animation Piece by Piece, and The Extraordinary Miss Flower, which is made by Iain Forsyth and Jane Pollard, who directed the Nick Cave documentary 20,000 Days on Earth.

There is also a screening of the silent Sherlock Holmes film The Golden Pince-Nez, being shown for the first time since its release in 1922 after restoration work by the BFI national archive.

This year, LFF is showing 255 films, of which 44% are made by female and non-binary directors, an increase on last year’s 39%. Matheson has previously said the film industry is “nowhere near [gender] parity” because it produces an “alarmingly” low number of mid-career female directors.

The programme includes a number of titles that won awards at previous film festivals including the film-making duo Fernanda Valadez and Astrid Rondero’s Sundance winner Sujo, Sarah Friedland’s Venice debut award-winning Familiar Touch, and Jacques Audiard’s Cannes jury prize winning Emilia Pérez.

This year’s talks feature Daniel Kaluuya, Sean Baker, Andrea Arnold, Mike Leigh, Steve McQueen, Lupita Nyong’o and Denis Villeneuve.