A law change aimed at decriminalising abortion will be debated in the House of Commons on Tuesday.
Two Labour MPs, Tonia Antoniazzi and Stella Creasy, have tabled rival amendments to the Crime and Policing Bill.
Speaker Sir Lindsay Hoyle could pick one or both amendments to be debated by MPs, but is likely to only pick one to go to a vote.
MPs are usually given a free vote on abortion, meaning they do not have to follow any party line on the subject.
Tonia Antoniazzi's amendment aims to prevent women from being investigated, arrested, prosecuted or imprisoned for terminating their own pregnancies.
She has argued that the investigations are "dehumanising and prolonged and the women forced to endure them are often extraordinarily vulnerable".
She said those investigated can be victims of domestic abuse and violence, human trafficking and sexual exploitation or women who have given birth prematurely.
"The reality is that no woman wakes up 24 weeks pregnant or more and suddenly decides to end their own pregnancy outside a hospital or clinic.
"But some women, in desperate circumstances, make choices that many of us would struggle to understand. What they need is compassion and care, not the threat of criminal prosecution."
Her amendment would maintain punishments for medical professionals and violent partners who end a pregnancy outside of the existing law.
It has received the backing from 176 MPs and the main abortion providers.
The Society for the Protection of Unborn Children has said the amendment is an "extreme and dangerous proposal" that would "effectively decriminalise abortions".
Stella Creasy has put forward a rival amendment which would enshrine abortion access as a human right and also aims to prevent women who have terminated their own pregnancies from being investigated.
Creasy has said her amendment goes further than her Labour colleague's proposal, by offering "protection to all those involved in ensuring that women can access safe and legal abortions".
Creasy has argued that Antoniazzi's amendment would not stop the authorities investigating "the partners of people who had an abortion or the medics who provided the abortions and it would not prevent demands for women to give evidence as part of that process".
It is backed by 108 MPs but not abortion providers. Rachael Clarke from the British Pregnancy Advisory Service has said Creasy's amendment is not the right way to achieve "generational change".
Speaking to the Radio 4's Today programme last week, Ms Clarke said abortion law is "incredibly complex", adding: "It is essential that any huge changes to abortion law is properly considered."
The Society for the Protection of Unborn Children has described Creasy's amendment as "even more extreme" than that of Antoniazzi's adding: "There's no way to bring an abusive partner who causes the death of an unborn baby to justice."