Mothers who kill their children may not be able to argue post-natal depression to avoid a murder conviction after a Government-ordered review of infanticide laws.

Justice Minister Phil Goff has asked the Law Commission to consider whether infanticide should be repealed, because sentencing laws now allow judges to consider mitigating factors for murder and vary sentences.

Any change to the law will spark an emotional debate about whether a mentally ill woman who kills her child should carry the stigma of being called a murderer.

There are also concerns the penalty for murder can be far greater than for infanticide, which carries a maximum penalty of three years’ jail.