Falling, Bush Theatre, London <br></br>Have I None, Southwark Playhouse, London

A funny-sad take on infertility

In the days before IVF treatment, an infertile couple at least had the grim consolation of knowing where they stood. There wasn't the agony of repeatedly dashed hope, as there can be now. That fate faces Linda, the 42-year-old teacher in Falling, Shelley Silas's moving, funny-sad new play. After five humiliating, costly efforts and miscarriages, Linda wants to draw the line and move on. Her partner, Pete, a gentle, considerate gardener, is torn between wishing he wanted what Linda wants and wanting to continue.

Their predicament is given an excruciating twist when Grace, Linda's 16-year-old niece, announces that she is accidentally pregnant. When the teenager offers to have the unwanted baby and give it to her aunt, her gesture only exacerbates the tensions in the childless couple's relationship.

Middle-aged infertility may collide with sexual precocity, but there's nothing neatly schematic about Silas's perceptive play. Patricia Kerrigan is magnificent as Linda, conveying every shade of conflicted feelings – the deep pain borne with stoic dignity, the humorous Scots honesty, the pride and hurt in her question to Pete: "What do you want more – me or a baby?"

Initiated into sex by an older boyfriend, Grace enjoys winding people up with her new sophistication (airily stating her preference, say, for marmite condoms), but, as Abby Ford's skilful performance suggests, this little madam is liable to lapse into a sullenly vulnerable little girl. At one point, Grace jokily propositions Pete, whose likeable boyishness and sorely tried patience are beautifully brought out by Adam Kotz. It's typical of the play and of John Tiffany's well-paced, sympathetic production that they manage to intimate a powerful, semi-sensual attraction. Pete is quietly flattered by this, but far too decent to exploit it.

It's a virtue that nothing is overstated. The irony of Linda adopting a maternal role towards a pregnant teenager (antagonising the girl's real mum) has too many awkward shades to harden into a pat diagram. When the couple reveal that they named their unborn children, it wrenches the heart.

Abby's mother accuses Linda of being jealous of people with families. There would be nothing for her to resent in the bleak world ofHave I None, by Edward Bond, at Southwark Playhouse. Set in 2077, it imagines an England where the state has outlawed family ties and abolished the past. Mass suicides are common. A man who claims to be her brother (Paul Cawley), arrives with no papers at the starkly functional flat that nervy Sara (Illona Linthwaite) shares with her state toady of a partner (Peter Marinker). With space limited and memory prohibited, logic suggests this liability will have to be liquidated. The play clumsily merges the tragedy of divided loyalties with the absurdist comedy of footling territorial tiffs over furniture.

Bijan Sheibani's production has an austere lucidity but can't disguise gaping flaws. It's not explained how this nightmarish regime won power or maintains it. It feels illogical that kinship is taboo, as it's customary for the state to exercise control through the nuclear family. Proceedings consequently have the smell of facile paranoia.

'Falling', to 30 Nov (020-7610 4224); 'Have I None', to 30 Nov (020-7620 3494)