Stephen Campbell Moore as Justin

Clémence Poésy as Kate

David Morrissey as Jon

Laura Birn as Theresa

Deborah Findlay as Tessa

Jonathan Harden as Mark

Tuyen Do as Allergy Doctor

Laila Alj as Sonographer

Christos Lawton as Phil

Stephanie Jacob as Registrar

Natasha Alderslade as Babyshower Woman (uncredited)

Anna Madeley as Abi

Sarah Malin as Sonographer 12 Weeks

Daniel Easton as Kate's Colleague

Franc Ashman as Indhu

Sam Pamphilon as Tom

Elliot Mills as Baby Billy

Joseph Mills as Baby Billy